TAC Tech => Racing => Topic started by: NOT A TA on August 02, 2015, 10:00:52 PM

Title: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 02, 2015, 10:00:52 PM
As part of the current rebuild on my 70 Esprit (with TA body parts) I'm doing several things which will hopefully make the car perform better for various high speed types of use. The car will spend a lot of time well over 90 MPH on road race courses, Land Speed Racing and open road racing. I've got several things I want to try and can't find much solid information on what actually works or doesn't and so I'll be doing a lot of testing, guessing, modifying, and more testing. If possible I'd like to get the car into the A2 wind tunnel for testing eventually but meanwhile I'll see what I can do with what I've got. I figured I'd document the process here for anyone interested now or in the future.

GM has has been using wind tunnels since the 50's.http://www.autoblog.com/2010/08/05/gms-wind-tunnel-turns-30/  I suspect the Pontiac engineers who designed the 2nd gen Trans Am used it to help design the new body style as well as the spoilers, flares etc. used on the Trans Am models. So my baseline is tuft testing the stock panels, spoilers, flares etc before modifications and then testing additional parts as well as modified factory parts.

 Here's a partial list of modifications. I welcome any comments, suggestions, etc.

Here's the plan

1. Extend air dam
2. Splitter
3. Belly pans
4. Side skirts & side splitters
5. Wicker bills in front of wheel openings
6. Rear diffuser, possibly two types
7. 3 different rear spoilers
8. Foilers behind wheel openings
9. Seal radiator support so only air allowed past is through radiator and brake ducts
10. Side window panels from cage to body to reduce chute effect on road courses
11. Roof fences?
12. Tire air dams
13. Front splash pan opening block offs
14. Modify fender vents
15 Rear wing

I'm a grassroots racer type guy. No engineering degrees, no supercomputer with CFD programs, no full size wind tunnel, no friends named Katz or McBeath, and don't have the math background to use Bernoulli's equation. However, I'll do as much testing as possible while building and then do track testing with video to see what actually works and how well in the real world.

The first modification is a taller rear spoiler. Lots of testing has been done on rear spoilers in general and for the shape of a 2nd gen the height after the first couple inches increases the downforce more so going from a 3" spoiler to a 4" spoiler doesn't increase the downforce as much as the change from say 4" to 5". The penalty is increased drag that will slow the car. Eventually I'll probably have 3 different rear spoilers and also full wing to test.

Although increased drag will lower the top speed capability the cars lap times on a road course may actually be reduced if the cornering grip is increased enough with the tall spoiler. I'll be making other spoilers for straight line top speed (less drag)and some for road course use so there will be several versions of aerodynamic prep I can set the car up with depending on what kind of race activity I'll be doing. At the same time I'll have most of the aero stuff removable so the car can look like a sort of stock bodied TA clone.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/018_zpsvxl4am3c.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/018_zpsvxl4am3c.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/010_zpssh85wnup.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/010_zpssh85wnup.jpg.html)



Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 02, 2015, 10:43:05 PM
(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/019_zps0uv8fjsv.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/019_zps0uv8fjsv.jpg.html)

Shown above is my rudimentary aerodynamic setup with very high speed additional wind provided by a Stihl leaf blower. Testing worked out surprisingly well to determine what I wanted to test for modifying fender vents.


(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/006_zpsth3q9sas.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/006_zpsth3q9sas.jpg.html)

The stock fender air extractor vent shown above (without screen) during base line yarn tuft testing at normal driving speeds shows the vent does work to help reduce air pressure underhood based on my crude testing. Even at normal driving speeds the vents pull air out of the engine compartment. As speed increases the vents pull more air. I have long strands of yarn inside the fender attached at various distances from the vent opening so I can see how much suction there is pulling air out.

Now the stock vent opening is about 15 Sq. In. and the stock screen blocks off about 5 Sq. In. of that. The air coming out is subjected to turbulence slowing it down which is caused by the screen itself. So anyone wanting to increase the breathing a quick 50% plus over stock can just remove the screens.

The vents help reduce underhood air pressure that causes the "floating" feeling that a lot of cars (including base 2nd gens) get at high speed. Having spent quite a bit of time over 120 MPH in my car I'll say it's very steady and stable feeling at speeds up to 150 MPH due to the stock TA aero parts I believe. Since I'm going to try and go a lot faster at Land Speed Races I want to make a set of vents that will optimize underhood evacuation with the least amount of drag. I also want to make a set that will help maximize usable downforce by reducing underhood pressure as much as possible and by design perhaps add some downforce by the exterior design of the vents themselves.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 02, 2015, 11:09:31 PM
Thought you might find this interesting: https://books.google.com/books?id=O4TXRK-juZgC&pg=PA30&lpg=PA30&dq=second+gen+firebird+wind+tunnel&source=bl&ots=RLQte9B-nH&sig=yqd1r8XrgKgwQBl-Ic2waxCybQA&hl=en&sa=X&ved=0CFkQ6AEwCWoVChMI78zkoJGMxwIVyBWSCh1rvQf0#v=onepage&q&f=false

Page 30 and 31 mention use of a wind tunnel in designing the aero pieces.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 02, 2015, 11:15:51 PM
Also found this posted by one of our members on another forum: http://www.firebirdnation.com/forums/topic/490514-aerodynamics-of-a-trans-am/

Another interesting discussion that took place right here on this board: http://transamcountry.com/community/index.php?topic=42840.0

Well if I bothered going past the first post obviously you know about the first link, but I'll leave it for others.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 03, 2015, 01:29:50 PM
Interesting info about using Chevy's aero test results to develop the TA parts in that Muscle Car History book linked by BOX.

I posted in the parts wanted section here to get some extra expendable fender vents I wouldn't be worried about hacking up and then tossing if my plans didn't work. Our fearless leader Mike Barefoot donated a set to the project and i got another set from Jack in exchange for some modified early 2nd gen engine mounts I've been working on. So I stripped them of paint and this way I'd have my stockers along with two more sets to modify so I can see the difference changes make by just doing all my testing on one side of the car and not having to reshape one vent over and over to test different theories.

The first thing I tried was changing the exterior of the vents to change the airflow and increase the suction of underhood air. I made two different designs and it appeared to me that both designs drew substantially more air through the stock openings with the larger more radical angle design pulling more air than the more streamlined one.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/007_zpsjkngfwhq.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsjkngfwhq.jpg.html)

Pic below shows the yarn tufts with no air movement and the more radical "just for the track Jack" concept mocked up with cardboard.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/004_zpsgu8pzwem.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zpsgu8pzwem.jpg.html)

Pic below is the track Jack concept with high speed air moving over it. You can see how air close to the surface is actually drawn backward from the rear of the vent housing to join the air coming out the vent opening. Seems to me like this also shows increased drag.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/005_zps9hux3vb5.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/005_zps9hux3vb5.jpg.html)

The streamline barefoot version shown below with the wind speed the same as the track Jack version pic shown above. You can see some of the long strands of yarn have been pulled out from inside the fender and how the boundary layer air moves over the Barefoot vent opening as opposed to above and below it as seen in the pic above.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/001_zpsfnww8gnc.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001_zpsfnww8gnc.jpg.html)





Title: Re: 2nd gen TA aerodynamics and modifications
Post by: jonathonar89 on August 03, 2015, 02:07:56 PM
Very nice stuff John!  Always seeing good work from you online.  I would like to see what you'd do if you had a 79-81 body.  The later body seems like a better starting point if talking aero.

I'd imagine new rear spoiler ends that extend forward and don't let the air roll off the sides.  That might play a big role in keeping downforce out back.  The Camaro was better than the firebird in this area but there might be a better custom end to make.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 03, 2015, 05:12:00 PM
Very nice stuff John!  Always seeing good work from you online.  I would like to see what you'd do if you had a 79-81 body.  The later body seems like a better starting point if talking aero.

I'd imagine new rear spoiler ends that extend forward and don't let the air roll off the sides.  That might play a big role in keeping downforce out back.  The Camaro was better than the firebird in this area but there might be a better custom end to make.


The first thing I'd try on a 79 would be a clear Lexan flat sheet that fit over the headlight openings. I had an 80 Monza Spyder with the dual square headlight openings similar to 79 TA's. I bought the car new and bought a kit to make headlight opening covers for it but could never bring myself to drill holes and what not to put mounting brackets on it.  Shoulda just done it as I ended up giving the car to the first ex-wife as a consolation prize/parting gift anyway. ahahaha

The Camaro rear spoiler end cap design does give more downforce supposedly. I tried reworking the end caps on my tall spoiler to be more  like the Camaro ones but they just didn't really look right so I extended the TA style caps so they stick out a bit wider at the outside corners to hopefully give a little more downforce being out in cleaner air on the sides even though the air rolls off the ends easier.  A fence of some type like is used on the sides of the rear extending aluminum pro stock style spoilers would probably help but look funny. The third gens pulled it off better with the wraparound style spoiler.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Black Sheep on August 03, 2015, 06:12:38 PM
Try blocking off your grilles so the only air going thru the radiator (and engine bay) is what's pulled in from under the bumper.  Pulling too much air thru the grilles makes the area underhood into a huge parachute.  Also, many high speed autos duct the air coming thru the radiator out thru the top of the hood, bypassing the parachute effect.

Bellypan and diffuser at the rear.

Suck in your bumpers

Really low ride height and side skirts.  If it don't scrape, it ain't low enough.

They do land speed racing about 20 minutes from me in Wilmington, Ohio.  Be happy to lend my shop if you wanna come and run :cool:
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 03, 2015, 06:38:38 PM
That Red Baron Pizza side extractor, should keep it like that.  Get some sponsorships and free pizza. :P

I too found it interesting Chevy did a lot of aero testing only for big wigs to turn it down because it wouldn't fit the Chevrolet image or what have you.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 77 TA man on August 03, 2015, 08:03:48 PM
Cool stuff! I never realized that aerodynamic testing was this intensive, thanks for posting!
As a side note, when I was doing the drivers ed course the instructor said a reason to not drive fast was that the cars areodynamics werent made to keep it pinned to ground; my thoughts were "you've obviously never have encountered a 2nd gen Trans Am, "Areodynamics of a stealth fighter".
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: jonathonar89 on August 03, 2015, 08:27:02 PM
Very nice stuff John!  Always seeing good work from you online.  I would like to see what you'd do if you had a 79-81 body.  The later body seems like a better starting point if talking aero.

I'd imagine new rear spoiler ends that extend forward and don't let the air roll off the sides.  That might play a big role in keeping downforce out back.  The Camaro was better than the firebird in this area but there might be a better custom end to make.

The first thing I'd try on a 79 would be a clear Lexan flat sheet that fit over the headlight openings. I had an 80 Monza Spyder with the dual square headlight openings similar to 79 TA's. I bought the car new and bought a kit to make headlight opening covers for it but could never bring myself to drill holes and what not to put mounting brackets on it.  Shoulda just done it as I ended up giving the car to the first ex-wife as a consolation prize/parting gift anyway. ahahaha

The Camaro rear spoiler end cap design does give more downforce supposedly. I tried reworking the end caps on my tall spoiler to be more  like the Camaro ones but they just didn't really look right so I extended the TA style caps so they stick out a bit wider at the outside corners to hopefully give a little more downforce being out in cleaner air on the sides even though the air rolls off the ends easier.  A fence of some type like is used on the sides of the rear extending aluminum pro stock style spoilers would probably help but look funny. The third gens pulled it off better with the wraparound style spoiler.

I haven't seen anyone a set but classic industries carries clear GTS headlight covers for 79-81 Firebird.  I have a few ideas myself but geared more towards 79-81.  Not trying to change your thread to 79-81 subjects/ideas so I'll stop here on that. 

Another crazy thought for you John is to form the front of your doors behind the fender.  You could also do this in the fender section somehow.  Herb Adams did that on his race car.  It would look somewhat like 1st generation Vipers in front of the door.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 03, 2015, 09:42:46 PM
Try blocking off your grilles so the only air going thru the radiator (and engine bay) is what's pulled in from under the bumper.  Pulling too much air thru the grilles makes the area underhood into a huge parachute.  Also, many high speed autos duct the air coming thru the radiator out thru the top of the hood, bypassing the parachute effect.



Bellypan and diffuser at the rear.

Suck in your bumpers

Really low ride height and side skirts.  If it don't scrape, it ain't low enough.

They do land speed racing about 20 minutes from me in Wilmington, Ohio.  Be happy to lend my shop if you wanna come and run :cool:

I ran my car with the ECTA back when they ran races at Maxton NC. Haven't been to the new place in Ohio. We had a venue here in FL I've run my bird at.  The Dade/Collier airport that was built for the SST planes that were given up on. The strip is 2 miles long and perfectly flat. Temps were a little high to make good power naturally aspirated but the boosted cars just turned them up a bit. I may end up in Ohio if it's closer than the Texas mile when the car is back together.

The Dade Collier LSR strip.

(http://i240.photobucket.com/albums/ff292/NOTATA/LSR%20Everglades%20oct%2009/milemarker-1008.jpg) (http://s240.photobucket.com/user/NOTATA/media/LSR%20Everglades%20oct%2009/milemarker-1008.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 03, 2015, 09:56:33 PM
Cool stuff! I never realized that aerodynamic testing was this intensive, thanks for posting!
As a side note, when I was doing the drivers ed course the instructor said a reason to not drive fast was that the cars areodynamics werent made to keep it pinned to ground; my thoughts were "you've obviously never have encountered a 2nd gen Trans Am, "Areodynamics of a stealth fighter".


While my car certainly won't be stealth by any stretch of the imagination with bright red paint and loud side pipes.  I'm hoping my efforts work out. The tuft testing I've shown is just the tip of the iceberg compared to what race teams do. For the vents I'm working on I'm just concentrating on the vent shape and openings now. Once I have the vents mocked up I'll be working on a sort of funnel shaped piece that will fit inside the fender to smooth the flow through the fender vent opening with the thought that increasing air speed through the opening will further reduce pressure under the hood thereby reducing lift more which will make available downforce more effective.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 03, 2015, 10:30:55 PM

I haven't seen anyone a set but classic industries carries clear GTS headlight covers for 79-81 Firebird.  I have a few ideas myself but geared more towards 79-81.  Not trying to change your thread to 79-81 subjects/ideas so I'll stop here on that. 

Another crazy thought for you John is to form the front of your doors behind the fender.  You could also do this in the fender section somehow.  Herb Adams did that on his race car.  It would look somewhat like 1st generation Vipers in front of the door.

Everyone, please feel free to chime in with any ideas, mods you've done, or mods your considering no matter what year 2nd gen. I purposely worded the thread title in the hopes of a free discussion on the whole 2nd generation not just "NOT A TA's aero crap". The whole aerodynamic topic is like a black hole rarely discussed. Those in "the business" have to be careful not to divulge secrets so they don't/can't say much and there's only a few guys in the world who publish anything useful to the average guy. Anyway, please feel free to discuss any thing related to 2nd gens of any year here. There's plenty of info out there on 3rd and fourth gens and I'll be happy to point those interested in the right direction for 3rd & 4th gen aero info but I'd like this thread to concentrate on 2nd gens.

While I'm making a lot of modifications, I'm trying to keep them easily changeable back to stock looking or things that can't be seen when the car is assembled. As examples, when I made the tall rear spoiler I made it with a slightly smaller footprint than the stock spoiler which is also ready for paint. So I can always put the stock one on and no one would ever know the tall one had been on the car because the register marks in the trunk lid paint will be covered by the stock spoiler. The way I plan on sealing the core support so the only air entering the engine compartment from the front is through the radiator won't be seen with the hood closed. Something like spreading the fenders to be wider than the doors I won't do because it'll affect the look of the car more than I want to live with on a semi-permanent basis. Most of the aesthetically obvious things I'm doing will be able to be added/removed fairly quickly. Not saying the wider fender thing won't work. It may in fact, but I'm taking a slightly more conservative approach.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 77 TA man on August 04, 2015, 07:36:05 AM
Cool stuff! I never realized that aerodynamic testing was this intensive, thanks for posting!
As a side note, when I was doing the drivers ed course the instructor said a reason to not drive fast was that the cars areodynamics werent made to keep it pinned to ground; my thoughts were "you've obviously never have encountered a 2nd gen Trans Am, "Areodynamics of a stealth fighter".


While my car certainly won't be stealth by any stretch of the imagination with bright red paint and loud side pipes.  I'm hoping my efforts work out. The tuft testing I've shown is just the tip of the iceberg compared to what race teams do. For the vents I'm working on I'm just concentrating on the vent shape and openings now. Once I have the vents mocked up I'll be working on a sort of funnel shaped piece that will fit inside the fender to smooth the flow through the fender vent opening with the thought that increasing air speed through the opening will further reduce pressure under the hood thereby reducing lift more which will make available downforce more effective.
Did you notice any difference normally driving the car with out the fender cent screens vs with the screens in?
Not sure what hood you have, but if its a shaker hood you could try running w/o the shaker?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 04, 2015, 09:16:48 AM
Cool stuff! I never realized that aerodynamic testing was this intensive, thanks for posting!
As a side note, when I was doing the drivers ed course the instructor said a reason to not drive fast was that the cars areodynamics werent made to keep it pinned to ground; my thoughts were "you've obviously never have encountered a 2nd gen Trans Am, "Areodynamics of a stealth fighter".

I didn't do any tuft testing with screens in place. I can do easily do that though and will report my observations.


While my car certainly won't be stealth by any stretch of the imagination with bright red paint and loud side pipes.  I'm hoping my efforts work out. The tuft testing I've shown is just the tip of the iceberg compared to what race teams do. For the vents I'm working on I'm just concentrating on the vent shape and openings now. Once I have the vents mocked up I'll be working on a sort of funnel shaped piece that will fit inside the fender to smooth the flow through the fender vent opening with the thought that increasing air speed through the opening will further reduce pressure under the hood thereby reducing lift more which will make available downforce more effective.
Did you notice any difference normally driving the car with out the fender cent screens vs with the screens in?
Not sure what hood you have, but if its a shaker hood you could try running w/o the shaker?

I never drove my car without the screens in the fender vents. I have run my car at Road Atlanta and Sebring road courses without the Shaker. I did that because my shaker was pushed up high by carb spacers and the shaker blocked my view enough so that I was missing the apex of one turn on each track. Without the shaker I hit the apex more consistently but it felt like the rear of the car was a little looser in other turns and radiator temps were higher. On a day when on track temps were over 100 at Sebring I had to take a slow lap in the middle of each 20 minute session to get the engine temps down. I suspect that was due to high pressure air from the windshield bow wave being forced into the engine compartment through the shaker opening which was working against the engine fan and increasing the air pressure under the car.

One of the reasons I'm trying to maximize the airflow out the fender vents is because a lot of the area under the engine compartment will be blocked off by the splitter that will extend back to the cross member and a belly pan behind that. Because I have sidepipes most of the bottom of the car back to the rear axle will be covered by belly pans. With the engine compartment sealed up pretty well I'll need to have enough flow exiting somewhere for the radiator fans to keep things cool. Hopefully the modified fender vents will be enough.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 04, 2015, 09:36:54 AM
Getting back to my testing, I added a small wicker bill (Gurney flap) to each of the cardboard mock up vents and tested. Adding the flap seemed to increase the suction of air out the vent while reducing turbulence and boundary layer reversion just aft of the vent. Notice in this pic the strands on the fender are all aimed rearward while in the pic above without the wicker the strand just behind the vent is pointing forward. both modified vents had similar changes with the track Jack vent appearing to pull a lot more air out of the engine compartment.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/007_zpsgbfqjnvj.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsgbfqjnvj.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 04, 2015, 09:42:37 AM
Really doesn't have much to do with aerodynamics as it does heat extraction, but do you still have the metal fender liners in place?  When I first looked at my brother's T/A there's no direct line of sight from the engine bay to the vents, so I always thought they were for looks more than anything but one day I noticed some air seemed to be coming out of them.  I'd imagine without the fender liners in the way they'd do a much better job.

Another thing I've heard of is people mounting PC fans or the like on the backside of the vent to forcibly pull air out, but with you spending most of your time at 100+ mph I'm not sure if they'd help or just be a hinderance.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 04, 2015, 09:50:07 AM
My next change was increasing the size of the opening itself in the vent to allow more volume. It appeared that even with the stock vent exterior shape the volume exiting increased while the boundary layer airflow was smoother. This leads me to believe the stock shape was capable of pulling more air but stylists probably decided the opening size and use of a screen.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/008_zpsyrrxn3wv.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpsyrrxn3wv.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: jonathonar89 on August 04, 2015, 10:55:09 AM
Really doesn't have much to do with aerodynamics as it does heat extraction, but do you still have the metal fender liners in place?  When I first looked at my brother's T/A there's no direct line of sight from the engine bay to the vents, so I always thought they were for looks more than anything but one day I noticed some air seemed to be coming out of them.  I'd imagine without the fender liners in the way they'd do a much better job.

Another thing I've heard of is people mounting PC fans or the like on the backside of the vent to forcibly pull air out, but with you spending most of your time at 100+ mph I'm not sure if they'd help or just be a hinderance.

Why wouldn't the fender vent not have much to do with aerodynamics?  Seems like a good pressure relief area considering how much air passes through a grill at speed and maybe a reason why its installed. 

Small computer fans seem like the biggest waste of time.  It would push if anything but to each their own.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 04, 2015, 10:58:36 AM
Really doesn't have much to do with aerodynamics as it does heat extraction, but do you still have the metal fender liners in place?  When I first looked at my brother's T/A there's no direct line of sight from the engine bay to the vents, so I always thought they were for looks more than anything but one day I noticed some air seemed to be coming out of them.  I'd imagine without the fender liners in the way they'd do a much better job.

Another thing I've heard of is people mounting PC fans or the like on the backside of the vent to forcibly pull air out, but with you spending most of your time at 100+ mph I'm not sure if they'd help or just be a hinderance.

EDIT: Jon put it above using less words while I was typing.

I'm not a aerodynamics or fluid dynamics engineer but I can tell you from experience that running without inner fenders at high speed creates a LOT of under hood air pressure. In a straight line it may not be a really big deal (like a drag car) but for any activity involving turning you need them.  The gel coat on the  fiberglass lift off hood that was on my 74 Camaro drag car was cracked and ruined when it bowed up about a foot in the center at over 100 MPH when the previous owner was running it with just Dzus fasteners on the sides and tried removing the inner wheelwells to reduce weight.

The engine compartment becomes a pressurized box with an open bottom (think hovercraft). The pressure is basically equal on the sides and top of the box (not taking into account outside pressures)) and so any opening on the sides will allow air to escape with the air taking the path of least resistance. In our case of trying to evacuate as much as possible we want to choose a place with the least external air pressure to place the vent. This seems to be behind the wheel on the side of the fender for most cars. I considered running 6" hoses from the vents to just behind the radiator fans but have decided it's not worth the hassle. I will however be creating a funnel shape for inside the fender to smooth the flow as it enters the vent opening.

With the hovercraft image in mind this is why we want to reduce the pressure under hood. A hood is roughly 4' X 5' so any change in the difference between the pressure above and below the hood will change the amount of weight on the tires. More weight= more grip so the track Jack vents will be designed to pull as much air as possible for max cornering. The barefoot vents I'm working on just need to pull enough air to keep the engine from overheating during 1 mile land speed races with the least amount of drag possible.

The volume of air moved by a PC fan would have a negligible cooling affect even when parked, they simply don't move enough air and depending on placement would probably slow the air movement out of the vents at almost any forward speed.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 04, 2015, 11:15:13 AM
The ones talking about them were mainly talking for around town getting heat out.  Maybe it was a small electric rad fan, but even the smallest would be too big I'd think.  I never really put much thought into what they were saying since I had closed off Firebird fenders so it didn't matter anyway.  If I ended up keeping mine I was looking towards T/A fenders and making a ducting of some type through the liners(didn't want to compromise crash safety on a street car by removing the liners, but good to know now about the aerodynamics effect) to the vents to let more heat out, since even with stock log manifolds my engine bay is an inferno.  Especially once I were to put on headers and redo the exhaust, something would have to be done.

Since you're going all race car maybe some heat extractors on the hood would help with downforce and letting heat out?  Sort of like the GT40, but obviously dialed down some given the space constraints.
(http://www.expressiveauto.com/images/Lamb-09/gt-40-hood.jpg)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 04, 2015, 11:33:36 AM
Couldn't find as good of a picture but maybe could graft in an early 4th gen hood:
(http://i92.photobucket.com/albums/l21/zigroid/1firebird.jpg)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 04, 2015, 12:03:29 PM
I'm not going all out race car although to purists it might seem like it. I'm simply trying to incorporate modern aero techniques to an old style body without altering the appearance with anything that can't be quickly changed back to stock looking. Kind of as if Pontiac's engineers could have modified a stock car  back in the early 70's for sports car and land speed racing using modern day aerodynamic knowledge.

To be most effective the hood radiator extraction openings would require other changes like switching to a bottom feeder and making a new radiator mounting. Neither of which I'm willing to do even though I have a spare hood although it might very well be advantageous overall for a better aero package. I believe most of the advantage on some of the newer cars is that by tilting the radiator they can make the front of the car more pointed and reduce the pile of air and bow wave before the bumper.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 04, 2015, 12:36:32 PM
In the pic below I added the Barefoot cardboard with wicker and it appeared that the vent could pull more air than even the larger opening could provide as the yarn tufts at the rear of the vent flipped to a forward direction. Seeing this I skipped testing the Track Jack version and decided to open the vents more.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/003_zpsixumgand.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003_zpsixumgand.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: jonathonar89 on August 04, 2015, 12:39:35 PM
If you do the under pan up, I think adding louvers with openings towards the rear would help pull out your engine bay pressure.  Hope to see some interesting stuff from you on that.  It's crazy to see a lot of the new cars having under trays made with condensed fabrics.  The only thing on your list I'm a bit at odds with regards to aero benefits is the foilers behind wheels. 
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 04, 2015, 12:50:50 PM
I remember reading where the '79-81 at least are bottom feeders, I didn't think about earlier cars not being that way.

Look forward to the "cardboard" vents being opened up and the results they bring.  Plus I think as a finished product they'll look really cool too.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Black Sheep on August 04, 2015, 03:29:58 PM
You want as much air as possible to go around the car and not thru it.  For drag racing, just block it off and run it, turning on your cooling system as soon as the run is over.  For anything longer than a 1/4 mile, you need to figure how to get air thru the radiator and out from under the hood.

And leave your inner fenders in :wink:
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 04, 2015, 04:30:20 PM
If you do the under pan up, I think adding louvers with openings towards the rear would help pull out your engine bay pressure.  Hope to see some interesting stuff from you on that.  It's crazy to see a lot of the new cars having under trays made with condensed fabrics.  The only thing on your list I'm a bit at odds with regards to aero benefits is the foilers behind wheels.

You're correct, the foilers probably won't do anything and may in fact may hinder but I bought them a loooong time ago, I like the look, and so I'm going to use at least the rear ones.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 04, 2015, 04:33:25 PM
I remember reading where the '79-81 at least are bottom feeders, I didn't think about earlier cars not being that way.

Look forward to the "cardboard" vents being opened up and the results they bring.  Plus I think as a finished product they'll look really cool too.

I'm farther ahead on the vents than my posts and will get caught up to date over the next couple days. On my out to dinner with a TA buddy now but I don't get in too late I'll post some more later tonight.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 05, 2015, 09:30:01 AM
I opened up the rear of the stock opening to the metal upright in the inner metal structure. Still seemed to be able to pull more air as seen in the pic below.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/005_zpsotjdkqep.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/005_zpsotjdkqep.jpg.html)

I decided to try cutting a slot in the fiberglass vent behind the metal support and was surprised to find yarn strands a few inches in from the slot were being sucked out the slot even with the stock exterior vent shape. Boundary layer flow seems good with very little drag. Perhaps something like this was what Pontiac's engineers wanted to make the vent look like before stylists got their hands on it?

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/014_zps1w4i655g.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/014_zps1w4i655g.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 05, 2015, 10:10:23 AM
With the more Barefoot cardboard installed (pic below without wicker) the drag increased apparently and the suctioning of yarn strands increased inside the fender.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/012_zps5stnjwd1.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/012_zps5stnjwd1.jpg.html)

Then I set up the track Jack cardboard setup (with wicker)and found I could really pull a lot of air out of the engine compartment pulling long strands of yarn 10" away taped by the hood hinge out the opening! However there appeared to be a lot of turbulence so I decided to try adding strakes to help smooth the flow and reduce turbulence.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/016_zps5nof9poe.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/016_zps5nof9poe.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/021_zpsacbb3bav.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/021_zpsacbb3bav.jpg.html)

The strakes seemed to straighten the flow coming out of the vent (pic below) so my thinking is that a little more air was being be drawn through with less turbulence. At this point my openings were limited in size by the metal inner structure and it appears the exterior vent shapes can still pull more air soooo the next step will be to start cutting the inner structure and open the vents up more!

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/022_zpsp7fqxmal.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/022_zpsp7fqxmal.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 05, 2015, 10:44:29 AM
After Box mentioned the hood vents I was trying to remember who's 2nd gen bird I'd seen them on. Then it came to me ! Bob Bertelsen's "Code Red". I don't know if it was done for aesthetics or function and whether or not any testing was done.

(http://i240.photobucket.com/albums/ff292/NOTATA/sw_640_zpsj2ytoyru.jpg) (http://s240.photobucket.com/user/NOTATA/media/sw_640_zpsj2ytoyru.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/Iw_640_zpsqksbampn.jpg) (http://s240.photobucket.com/user/NOTATA/media/Iw_640_zpsqksbampn.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 05, 2015, 02:15:34 PM
After thinking about it the Stabil 360 Camaro had some pretty wild stuff done to it as well:
(https://s-media-cache-ak0.pinimg.com/736x/67/fd/83/67fd834beb00ba6c6735e500bf652153.jpg)
(http://coolridesonline.net/wp-content/uploads/2014/01/12-999937_600353493370011_435557578_n.jpg)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: hakitup on August 05, 2015, 02:58:58 PM
Great info I love what your doing, this is what makes racing/innovation fun. I so want to get a go-pro, string the car and see what the air is doing!!

Tom H
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: pancho400cid on August 05, 2015, 06:58:31 PM
Wow... very interesting discussion.  Unfortunately that's about all I have to add....  Although I have solved Bernoulli's equation a time or two!

My uncle was a wind tunnel test engineer.... unfortunately he passed away a couple of years ago.  He would have been WWWaaaayyyy into this discussion!
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 05, 2015, 09:25:06 PM
Wow... very interesting discussion.  Unfortunately that's about all I have to add....  Although I have solved Bernoulli's equation a time or two!

My uncle was a wind tunnel test engineer.... unfortunately he passed away a couple of years ago.  He would have been WWWaaaayyyy into this discussion!

Someone like your uncle would be an awesome resource to learn from.

A bud of mine was in town on business the past couple days. He's a fluids specialist and happens to be a Trans Am owner with a 70 Ram Air III who's always been interested in the modifications on my car. I asked him his opinion on several things I'm working on and discussed axial flow type pumps as a possibility for brake duct use. I explained most of the current aero upgrades and why I'm doing certain things certain ways. He agreed with pretty much everything I've planned and had a couple suggestions.

Surprisingly his first mention about fans to pull air out of the engine compartment were the computer type fans Box mentioned TA guys using with the stock fender vents.

Getting back to the fender vents. I removed a lot of the unnecessary metal inner vent mounting structure. Looking at the design I decided the vertical metal section was probably incorporated to keep the inner structure from bending or twisting before and during installation (spot welding) to the fender skin. So I cut it out and opened up the leading edges as well so I could make the vent opening as large as possible. With a stock fender vent in place no one could tell from the outside. With a modified vent you can see some of the inner structure if you look and are close. From any distance more than a few feet no one would notice.

 (http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/007_zpsatar3nzu.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsatar3nzu.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/006_zpsvk81p9sj.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/006_zpsvk81p9sj.jpg.html)

I'd put a slot in the vents previously and decided that now that there is no support in the way I'd try opening up the vent even more. I won't bore you guys with a lot of different pics of the progression of tuft tests but the Track Jack design with wicker, strakes,  and wide opening seems to pull the largest volume of air through the vent. I kinda like the looks of the stock vent with the big opening and it seems to have the least drag.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/016_zps4etgb5xy.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/016_zps4etgb5xy.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/014_zpseqebpuk3.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/014_zpseqebpuk3.jpg.html)

The large opening of the Track Jack vent now has over 30 Sq. In. to draw air through which is more than 3 times the stock vent with screen. When combined with the increased angle, size, wicker, and strakes I'd imagine it can pull 4-5 times or more the volume of air that a stock vent can pull. I'm going to see if I can find someone with a flow bench I can test my theory and designs on. Meanwhile I'm going to modify the vents to be ready for paint. I'll be making a flow straightening piece to fit inside the fender vents the next time I have the fenders back off the car (which will be pretty soon).

Here's the difference between stock and modified size openings.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/015_zpsqfrdibft.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/015_zpsqfrdibft.jpg.html)

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 05, 2015, 11:39:32 PM
Did some quick looking and there are pc fans capable of moving 300+ cfm.  Mounted into a sealed housing/ducting I'd think they'd be pretty effective, so 600 cfm being moved out even when stationary would be the bee's knees.

Liking the big vents, functional and look cool.  Kind of curious as to how much air they'll move at your average track speed and highest back straight speed, though not sure of a good way of testing that without a wind tunnel.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: mrbandit on August 06, 2015, 07:07:59 AM
Someone mentioned extractors on the hood and that has been done before, but that would mean Jon would need two hoods for his plans.  Not that he couldn't, but hoods take up a lot of space.   :D

For the pic....
(http://i80.photobucket.com/albums/j174/TransAm455/1BIB1.jpg)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: mrbandit on August 06, 2015, 07:34:08 AM
I can't really offer any real world auto experience at this level, but I do have observations from the IT industry that I feel are applicable.  Over the past 20 years server internal layouts have evolved to seperate elements of the board as well as to direct air flow in a straight line thru the server case.  PC fans are laid out to pull air front to back.  With that in mind the PC fan would have to push\pull an equal or greater amount of air then your radiator fans to make a difference in my opinion. 

Also, are you going to modify the way air reaches the carb rather then using the cowl effect with the shaker?  If you utilized ducting to ram air in like a Olds W30 setup to the carb couldn't you use the shaker as a large extractor?  Maybe even make a low profile shaker to increase your track visibility?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 06, 2015, 09:46:00 AM
Someone mentioned extractors on the hood and that has been done before, but that would mean Jon would need two hoods for his plans.  Not that he couldn't, but hoods take up a lot of space.   :D

For the pic....
(http://i80.photobucket.com/albums/j174/TransAm455/1BIB1.jpg)

I do have the flat hood with a shaker hole cut in it that was on my car until this rebuild available as a spare that could be modified and I would be willing to modify it if I thought there was a significant advantage. As mentioned, storage is a problem and this is my solution. It's over the workbench in the shop.

(http://i240.photobucket.com/albums/ff292/NOTATA/001_zpsocn5fqpi.jpg) (http://s240.photobucket.com/user/NOTATA/media/001_zpsocn5fqpi.jpg.html)

It's my understanding that there's only a couple places on the hood of a typical car where extraction vents have been reported to actually function to pull air OUT of the engine compartment.  Usually that's near the middle fairly close to the front of the hood just behind the core support or about 3/4 back near the sides of the hood (like the 3rd gen GTA's).

 While they might provide some engine cooling advantage (which I doubt except when not moving) I believe the vents shown in the pic above of the hill climb car would actually let the high pressure air at the base of the windshield go IN to the engine compartment and then under the car. This would cause lift and reduce grip in the rear, maybe that's part of the reason why the rear got loose and one wheel is off the road? Additionally, by increasing the under hood pressure at speed they may actually be making it harder for the radiator cooling fans to cool the engine. The rear of the hood being up so the hood to cowl seal isn't functioning would also increase under hood and additional pressure/lift under the car because the air at the base of the windshield will be allowed into the engine compartment then under the car.

 I made a plug for my open/no flapper shaker once because I was going on a 1000+ mile trip in torrential rain and didn't want the paper air filter getting soaked. The plug kept getting pushed into the shaker out on the highway even though it seemed pretty snug when I made it and I have a dual snorkel shaker base that had the snorkels unplugged. Every time I got up over 60 MPH or so the plug would get pushed into the shaker. That convinced me that the shaker actually functioned to provide cool air (although not actually Ram Air).

With the car running at rest the radiator fan pressurizes the engine compartment slightly above normal atmospheric pressure. So the air entering the carb would come primarily through the snorkels rather than the shaker opening. This also allows the vacuum operated heat riser system that pulled warmer air off the exhaust to work during warm up. Once the car is moving there comes a point as speed increases where the pressure increase at the base of the windshield reaches the shaker opening and once the pressure at the shaker opening becomes greater than the air pressure under hood the air being pulled into the carb switches from entering the shaker base through the snorkels to entering through the shaker opening. At extremely high speeds I suspect there is more air entering through the shaker opening then the engine requires and "extra" air is being forced backward through the snorkels into the engine compartment which is not good.

(http://i240.photobucket.com/albums/ff292/NOTATA/Firebird/003_zpssqfkltog.jpg) (http://s240.photobucket.com/user/NOTATA/media/Firebird/003_zpssqfkltog.jpg.html)



Title: Re: 2nd gen TA aerodynamics and modifications
Post by: mrbandit on August 06, 2015, 10:34:07 AM
That makes good sense and thank you for that in depth explanation.   With that in mind have you ever tried extending the shaker entry further to the windshield to possible speed up air entering into the shaker.  Similar to how Herb did it back in the day?  Would it be worth the trouble?

(http://i491.photobucket.com/albums/rr273/vsefiream/Fire%20Am%20stuff/Other%20Herb%20Adams%20stuff/WatermarkedImageHandler2ashx.jpg)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Bigger is Better on August 06, 2015, 06:03:51 PM
Hey I am not friends with McBeath either but I have read his book and some of his RaceCar Engineering articles and I stayed at a Holiday Inn last night;)  Actually his book Competition Car Downforce is a great intro book into aero with some great real world data and suggestions, I recommend it.

Not a TA, interesting work and I dig your car and this thread.  I dont go online/forums much so sorry if I dont respond quickly.  I will share my experience, my car was (I crashed it in that corner many years after that pic actually and bounced the car to the inside of the hill, rolled it a few times, I am building a new one slowly) an autocross, solo I (high speed track timed events) and hillclimb car, I raced for it about 25yrs.  The need for more downforce for me really was driven from the hillclimb where the corner speeds are high.  The first issue to resolve is to reduce the front lift and then balance in the rear.

I am fortune that these guys are local and are my friends, they are multiple time SCCA A Mod National champions and as you can see are very interested in aero ;) so they are a good sounding board.
(http://www.vcmc.ca/forum/attachment.php?attachmentid=182&d=1278914551)

The hood vents were there mainly for heat control, they are 280Z vents by the way, but we placed them further back to help relieve the high pressure air build up against the firewall.  I did wool tuff them and they seemed to work, the high pressure zone in front of the window is really only a couple inches thick so they (and the shaker for that matter) are really to far forward to get a lot of impact from them.  I got a crappy hood to cut holes into, we had to glue the inner/outer layer together and I just did a bad job and with worn hinges it just fit really bad, the cowl seals were still functional

My front splitter was a combo 1.5 inch extension of the front air darn and then the splitter that pulled foward to about 1.5 inches ahead of the front nose profile looking down.  It was made of aluminum honeycomb so really strong.  The next iteration was to put side plates on it and some mini diffusers that would reach into the wheel well (C5R corvette style).  It made my car feel alot more stable at 100+mph (reducing front lift), it felt like it was doing 60mph.

The factory wheel front flares are benifical as well so we are lucky GM did that for us.

On the rear I used an rear spoiler extension, the hieght of the overall spoiler was actually from McBeaths book as a percentage of the wheelbase to maximise downforce and balance aerodrag.  My next steps for that was also end plates to help preventing the high pressure zone from sliding off the sides.   A wing would be a lot more effiecient and give a lot more downforce but I didnt look the looks of it on a second gen (I have a seen a few onlne that look ok since).  I have a better pic of my car but I cant seem to figure out how to attach it??

Here is a link of one of my compititors who has mroe evolved aero (http://bigboymedia.net/wp-content/uploads/2011/05/KNOX_HILL_CLIMB_0323_wp.jpg)

That was about all I was able to due to the rule set.  I think all the stuff you list are good options.  I would typically start with stopping as much air as you can under the car (front spoiler, side skirts), removing high pressure under the car (hood/fender vents, diffuser - that only really works with a flat bottom car) and aero on top (spliiter, wings, canards...).

Johnny
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 06, 2015, 06:51:56 PM
That makes good sense and thank you for that in depth explanation.   With that in mind have you ever tried extending the shaker entry further to the windshield to possible speed up air entering into the shaker.  Similar to how Herb did it back in the day?  Would it be worth the trouble?

I haven't tried extending a shaker, not sure how much you could extend it with a hinged hood. The car shown in t6he pic has a lift off one piece front end so they can do it more easily. I have worked on cars with cowl induction although I have no test data to support any worthwhile gain. I've seen a lot of cowl induction hoods not being used properly that I'm sure make the car worse overall than just having a stock hood. Many people don't seal the hood so that the only air going in the induction opening can only go into the carb itself.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 06, 2015, 08:47:44 PM
Johnny, thanks for joining the discussion! Your car was very cool, good to see you're building a new one. . I've got questions!

I considered making an adjustable rear spoiler extension so I could raise it up high like your's in hopes of balancing the downforce from the new splitter etc. up front. In the end I decided I'll probably end up with a wing eventually so made the tall spoiler 1.25 taller than stock and I smoothed the metal tail panel nicely in prep for paint where the fiberglass tail panel normally covers. If/when I want to build the wing I'll remove the fiberglass panel and bolt the wing supports to the points where the fiberglass panel and bumper bolt on. The wing will probably be the same one or very similar to the one used as the spec wing on the Pirelli World Challenge cars this year. For me it's easier to use something already proven than start from scratch trying different cord lengths etc.

How thick is the honeycomb aluminum you made the splitter from? What did you put on the leading edge? Are there rub strips on the bottom? How high off the ground was it when static? I've got my car sitting on the bumpstops without springs in the car now determining splitter height. I figured I'd start at about an inch clearance with the rear high and the front end sitting on the bump stops. I planned on using some type of rub strips on the bottom like skateboard rails.

I planned on getting to the front air dam extension and splitter stuff eventually in this thread but here's a pic when I was doing some cardboard templates mocking things up before I stripped the car to the shell. I'm going to try and make the section forward of the engine cross member easily removable for loading & unloading the car from the trailer. I'll also try to make it hinged so it can raise if it hits road course curbing or something on the rub strips under the splitter.

I plan on making the car flat bottom which is a bit easier for me than most 2nd gens because of the side exit exhaust. Without an independent rear I'll have to deal with the best way to work with the stick axle but the rest of the bottom should be doable.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/MVC-020F.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/MVC-020F.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Bigger is Better on August 06, 2015, 10:41:25 PM
Hi John,

I thought about the adjustable rear spolier as well and my orginal template was for that but then ran out of time so just bolted it to the max hieght and left it there.  For my car all the aero was removable so I could drive it on the street without looking too dorky ;) and with ground clearance.

For the splitter I made a carboard template just like yours.  The honeycomb I had was 1/2 inch but I would go thiner on my next one, maybe 3/8.  Those guys with the formula car pic built that car from it (its monoque really cool) and we got it a metal surplus place, it was marine grade from a big ferry project here.  Overall it was overkill but again I would go 3/8 I think, you could produce a couple hundred pounds of down force on it so you want it to be strong.  We tested it by putting two men on the end and it flexed a bit but help up.

I then made some adjustable (Hiem) mounts to reach up into the bumper of the car, not sure on a early car whats up under the nose though.  The rear of the splitter went all the way back to the leading edge of the wheel well (rules didnt let me go back more) and it was bolted to the rad support with some adjustable brakets.  The spoiler extension that reached up to the factory spoiler I made adjustable to move front and back in case I changed the hight a lot, dont think I needed too though.  Overall I used 4 pins for the front mount and 4 bolts for the rear so I could install it pretty quickly.

For the leading edge my buddies told me the process to seal the end of the honeycomb, basically a mix of epoxy and a lot of mini glass air bubbles (I got them from a fibreglass place).  So the mixture is light and probaby more important easy to sand so you just sand it to a bullnose shape.  I didnt use strips on the bottom but I should have on the leading bottom edge.  One of Carrol Smiths book covers more complex honeycomb joing process if you build tunnels in it.

I dont remember by overall hieght in the end but it was probaby 2.5 inches off the ground in the front to make up for braking compression and bumps and with a 1/2 rake as a front type diffuser effect.  The more foward it reaches the bigger the ground clearance problem, I think on your car the nose is a fair bit shorter so depending on how far you want to move it forward you can make it lower.

Those world challenge wings are pricey $$$, I pit for a world challenge corvette once at the Vancouver Indy and I think he told me it was over $10K (mind you that was like 15yrs ago).  There are a lot of good wings for the american iron NASA serious so that might be a better choice.

I really like your fender vents mods, I think I would worry less about the air flow quality and just maximise the size like you have as I think with the higher pressure under the hood then the air on the side of the car and that even a hole in a flat plate will create vacuam when you move air by it your 95% there.  Depends how much time you want to spend there (I sense you like to maximise things haha).

If you do a flat bottom, and I think thats a major job, you can use a thinner honycomb so you dont need a big frame structure say compared to a flat plate.  Maybe bolt it to the rocker panel flange.  Also you should try to build two tunnels, they would not have a big profile but one up each side of the diff pumpin.  Again I think it would be hard to do but curious to see what you find out.  There is a lot of potentional in a flat bottom and tunnel/diffuser setup but you could have some other challenges like transmission and diff cooling, hard to tell.

My new car is on the rotesseire waiting to get blasted and I have the engine apart but I am hoping to have most of the body ready on the car again by year end so then I can start the aero projects again.



 


Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Bigger is Better on August 06, 2015, 10:44:48 PM
Hi John,

One more thing I see those pics of the rear wheel well spats, I think from a downforce perpective they are not ideal as they dont let the high pressure air in the wheel well exit.  The factory front spats with the rear open falling away bodyline is pretty ideal I think.  I am not sure from a drag perspecitive which is better, but hey thats just another reason for more HP ;)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 06, 2015, 11:27:49 PM
Could always get this: http://www.heidts.com/part/1974-1981-camaro-pro-g-irs/  8)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: RatOne on August 07, 2015, 12:01:55 AM
What did you use to make the rear spoiler taller? Looks great
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 07, 2015, 12:09:43 AM
Looks like perhaps he used Bondo Glass, which is fiberglass reinforced.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: mrbandit on August 07, 2015, 07:10:31 AM
RatOne, John has a killer topic in the Projects section.  Here is the post on the spoiler.  http://transamcountry.com/community/index.php?topic=47001.msg656574#msg656574 (http://transamcountry.com/community/index.php?topic=47001.msg656574#msg656574)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: mrbandit on August 07, 2015, 07:15:01 AM
John, I don't want to jump off topic here as I think this is great information, so I'd like to add a question for later in the discussion.

I was wondering if you planned to "flow the air" differently around your headlight bowl.  Perhaps a cap of some kind? 
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 07, 2015, 09:03:24 PM
Johnny, Thanks for the tips on the Splitter! I've got a couple options for the supports that hang in the front.

I had the opportunity to spend some unhurried time going over a couple of the current World Challenge cars and took some good pics of how they braced the wing supports. Although I jokingly made somewhat of a disclaimer in the first post of this thread saying I didn't have Dr. Katz  or Simon as buds to help me, I have spent a long time studying & learning as much as I could about things related to aero design for race cars. So getting to go over some of the most up to date cars with no rush was awesome. Hopefully some of the folks who follow this thread will learn something they may not have ever heard of or thought about. Who knows how many already googled Bernoulli and learned about his principal? Or how many will google the Magnus effect now or when the subject comes up later on in the thread as my aero mods progress? I didn't want to overload the thread right away with lots of tech so I figured I'd start with tuft testing (cause it just looks cool and is visually graphic) and eventually work my way into manometers and such which can tell us more (but don't look as cool, hehe).

I have looked at the wings on the CMC, AI, and  other race cars at events walking the pits chatting between my sessions. I'm going to build everything else and get the car back on track before building the wing. As is, the car will once again be better than the driver when I get it back together. The last few times I had the car on track the instructors told me I needed to get a "better" car. I said "I like this one, I'll just make it better!"

as for the vents, I've maximized the opening and am just making the exterior shapes different because I don't want the vents to add any unnecessary drag at the land speed races. I'm going to try and get up to 200 eventually and need all the help I can get! For the track vents I want to pull as much as possible from the engine compartment. Keeping the engine cool with an almost complete flat bottom without creating lift is going to be tough.

I've built cars with flat bottom using thin sheet aluminum and I'd like to try tunnels but I think it would add too much time to the overall project. So for now I'll be doing a regular flat bottom. Haven't decided on material yet. I'd like something strong, light, and cheap! Ya, Ya, Ya, I know, I only get to pic two, darn. Perhaps I'll try tunnels in the future like the wing.

I've been thinking a lot about the hood vents on your car and your tuft testing which kinda seem at odds with my observations on my car with the hood scoop plug that was getting pushed in. I'm going to ponder it another day and then write a post about it, I hope you'll comment on it after reading.



Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 07, 2015, 09:07:54 PM
Hi John,

One more thing I see those pics of the rear wheel well spats, I think from a downforce perpective they are not ideal as they dont let the high pressure air in the wheel well exit.  The factory front spats with the rear open falling away bodyline is pretty ideal I think.  I am not sure from a drag perspecitive which is better, but hey thats just another reason for more HP ;)

I know the foilers aren't great for aero BUT, they do look cool (on some cars). I've already mocked up wicker bills for the front of the wheel openings to be added to the stock flares and will discuss all the stuff going on by the wheels at the same time later in the thread.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 07, 2015, 09:18:17 PM
What did you use to make the rear spoiler taller? Looks great

Thank you! I built the spoiler and posted details in my project thread before I decided to create this spin off thread dedicated to 2nd gen aero. For those who don't want to bounce around following links and searching through a long thread the basics are. Stock spoiler stripped of paint, holes drilled in/through, and roughed with 36 grit on a small right angle grinder pad. Roof flashing used as a kind of one sided mold then fiberglass resin & cloth to build up followed by skim coat of plastic filler and normal prep block sanding and priming.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/011-5.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011-5.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/001-14.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001-14.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 07, 2015, 09:21:15 PM
Looks like perhaps he used Bondo Glass, which is fiberglass reinforced.

Dunno if you ever tried it but Kitty hair bondo has strands in it. Don't like it myself but if you're doing a quick cheap patch on a rust hole in a beater it works better than regular fillers.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 07, 2015, 09:59:17 PM
John, I don't want to jump off topic here as I think this is great information, so I'd like to add a question for later in the discussion.

I was wondering if you planned to "flow the air" differently around your headlight bowl.  Perhaps a cap of some kind?

I don't have a good plan for the headlights themselves. I will be working with the park/turn lights and lower valance to reduce turbulence and will write a post about headlights and the lower section over the weekend because I'd like ideas and it'll take time to get the vents looking nice and in primer anyway. PLUS,.... Hey, this is YOUR house, we can discuss anything YOU want! By the way thanks again for the vents! The white ones were the ones you sent and will be the high speed aero ones.

As for the vents, I sliced them up, taped the pieces of them together to change the angles etc. and used fiberglass resin & cloth to make the new shapes. Here's the pics.

Slice and dice then tape.

 (http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/Barefoot%20and%20Track%20Jack%20vents%20002_zpslz3vt75a.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/Barefoot%20and%20Track%20Jack%20vents%20002_zpslz3vt75a.jpg.html)

With the inside glassed and holding their shape they look like some kind of weird tile art wall hanging you'd see for sale at a local crappy crafts festival.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/Barefoot%20and%20Track%20Jack%20vents%20005_zpsv1gapc5a.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/Barefoot%20and%20Track%20Jack%20vents%20005_zpsv1gapc5a.jpg.html)

Rough shaping done and trimmed. Will work on them a bit more with the fiberglass then go on to skim coat of plastic filler & paint.
(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/Barefoot%20and%20Track%20Jack%20vents%20006_zpsqmsdbz4r.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/Barefoot%20and%20Track%20Jack%20vents%20006_zpsqmsdbz4r.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Bigger is Better on August 08, 2015, 12:13:42 AM
Hi John,

I figured you had done more homework on aero then what you mentioned haha.  Here is a cool site if you have not seen it yet, its got lots of info on real race car aero work http://www.mulsannescorner.com/

Yeah let me/us know what you think about hood vents, I am not confident mine are in the best place.  The theory is you are pushing a lot of air into the engine bay from the front of the car and it will move back until it hits the firewall and then exit the bottom of the firewall so there would be the highest underhood pressure close to the firewall.  The wool tuff test was at about 70mph so not that fast so maybge 100+ there is a different response.  Just to give you an idea on the location the back of the vent is at about the back of the shaker opening and for the side location the drivers side vent was right over the master cylinder and if you look under the hood there is not a lot of space left to move it further out.

I think in a lot of real race cars with the front mount vents those have much better underhood air movement strategy (ie, front exit vent sealed against the rad).
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 08, 2015, 10:48:19 PM
I started taking my car to the Lime Rock Park road race track for HPDE events about 15 years ago. In the beginning the car was better than the driver even with the original 350 2V and stock brakes with heavy duty brake pads/shoes on the relatively short track. As I got better as a driver, started going to bigger tracks like Road Atlanta and Sebring, and installed a bigger engine. I'd gotten up to the point of running Porterfield race pads in front with custom made race compound shoes in the rear for the drums. The limits of the stock brake system started to become very obvious. I'd overheat the brake system crystallizing rotors, melting the caliper seals, and the wheels would get so hot the plastic Firebird emblems in the wheel center caps would melt and deform.

I decided run some air ducts to the rotors to help cool things until I could get different wheels that would allow bigger rotors and better calipers in front and add rear discs. Being too picky for my own good I wanted brake ducts that looked like something that would have been done on the actual Trans Am race cars of the early 70's instead of doing something easy. So I decided to install lightweight plastic halogen headlights with LED turn signals built into them so I could use the park turn signal opening in the splash pan for the brake cooling duct opening and still keep the car street legal.

I Installed the headlights along with some stainless steel Jeep headlight protective screens designed to keep headlights on off road trucks from getting bashed. Cars with glass headlights are required to put tape over them on some race tracks and I never liked that "look" in pics of cars on track. I tried to figure out a way of attaching some sort of headlight cover for track days that would look like the early TA race cars with a # on one of them but never figured out something that wouldn't mark the paint up. I decided to use the screens and liked the look so even with plastic headlights I wanted to use them.

Once the headlight modifications and install were done life got in the way and I never did get the brake ducts installed. I'd gone through all the time and expense to make the original park turn signal available for the ducts but "stuff" happens... I had a case of Lyme disease for a few years prior and didn't know it, slowly becoming less and less able to do anything. Closed my business in CT(which was doing fine) because I just couldn't run it anymore. Bought a home in FL to move to (thinking getting old, dying). After collapsing on the floor in CT several times, calling docs in the fetal position unable to move,  eventually I got meds that got rid of the majority of Lyme symptoms (recovery took more powerful meds and the next few years though). then my truck & trailer with lots of my valuables was stolen while moving to FL (ins wouldn't cover). Bought another truck & trailer and finished moving only to find the new (to me) house was burglarized and not only was everything in the house taken but the house was flooded and black mold made it uninhabitable. This occurred while I was at the old house for a couple months while selling it. Got deposit on old house, flew to new house, found it empty & destroyed. Lawyer said I had to complete sale on old CT house or risk suit. With no usable home I put the cars in a storage facility in FL and "Borrowed" a friends summer home in CT to live in. I battled for over a year with Insurance that wouldn't pay for the damage to the FL house before caving in and accepting less than 1/2 the cost needed to repair (never mind belongings)since I had to move on with life. Concurrently occurring during the same time period my Malibu which had been sent to have a roll cage installed was bouncing around being stored who knows where while the guy that was supposed to do the install had all sorts of problems/excuses and it took over 3 years with police intervention on multiple occasions before the car was finally returned with a cage install a blind welder could have done better.  Then the new house got burglarized again within a year of finally moving in and ins wouldn't cover because house hadn't been fully repaired from first break in. To this day I still have force placed Insurance on the house. Boy, have I digressed! So anyway,  the brake ducts were the least of my concerns for several years and once I finally got the car back out of storage I just drove it.

Meanwhile, I've learned more about aerodynamics and have decided not to use the park/turn opening for the brake ducts. The park/turn opening is at the end of the bow wave on the outside so air will be moving sideways across the opening pretty fast rather than straight at it. Also the lower the opening is in relation to the splitter the less pressure there will be on the splitter in front of it. So I've decided to move the duct openings to the radiator support up high on the sides of the radiator. The higher they are and more centered they are the more air will move through them. I'll probably also use fans in the middle of the ducts to keep airflow up during slow sections on track and for cool down heading to the pits.

I will make some plugs that fit into the park/turn opening as flush as possible with the splash pan to reduce turbulence. I may also make plugs for the center openings in the splash pan to increase pressure on the splitter and smooth the bow wave flow. The stock style radiator/shroud/clutch fan I was using (worked fine) will be replaced with big aluminum radiator and electric fans in anticipation of much more powerful  (producing more heat) engine.  I don't have a plan to cover the headlight openings now but am open to ideas because if/when I get to the point of trying to hit 200 MPH at LSR's I'll need all the help I can get! If someone's got a good idea I'd make it now to paint with everything else.

The top pic below shows where I'm planning on putting the brake ducts. Middle pic shows how I originally intended to use the turn signal opening which looks really cool but adds turbulence, reduces pressure on splitter, and weighs more. Bottom pic is how it looked before taking the car apart ready for the duct install.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/003_zps7h9kvapc.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003_zps7h9kvapc.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/016_zpsbfqlhucu.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/016_zpsbfqlhucu.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Safety%20upgrades/The14Carinterior480.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Safety%20upgrades/The14Carinterior480.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Jack on August 09, 2015, 06:19:37 AM
I'm just seeing this thread now, great work John very impressive. Having a 70-73 large “in your face” grills helps tremendously with keeping the engine temp down but obviously does not help with the under the hood pressure. I see you are performing all of the tests without the inner fender wells, which I think is the biggest problem. The inner wells block the fender vents but at the same time they are perfectly positioned in the engine bay to pull air to the vents if slots are cut in the wells. This however may create problems with building up a lot of pressure within the fender compartment, but I think having a larger vent will help with this issue. I think if the inner fender well is cut directly above the control arm by 4-5” vertical and the ends by 0.5-1” horizontal to allow the well to be bend into the engine bay will do the trick. The other issue I see is the hood and all of the bracing, I would install something under the hood to make it smooth and not create any turbulence under the hood. New cars have insulation that are provided to control heat but act the same way. The hood I think is one of the biggest problem especially with the shaker and if the seal is not one tight. Air will get in from the area around the shaker and create similar issues.

Mike, the fender vents work like data centers with hot/cold isles, the engine bay works like the containment system with the vents as the chimneys except they are not large enough and don’t have any fan assist. The vents are perfectly positioned at the back of the engine bay but are isolated, a lot of pressure will need to be build up before the air is pulled from the engine bay, so adding openings within the inner wells will help tremendously especially with high speeds.

And John thank you for the mounts, I got them installed last weekend and my son already tested them if you know what I mean.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 09, 2015, 09:37:46 PM
Jack,  the tuft test pics posted were taken without the inner fenders in place on purpose. My main goal during initial testing was to see how much air I could pull through the fender vent to test the angle & shape of the housing as well as the size of the opening possible in an effort to move the largest volume of air. A bud was holding a very high speed leaf blower just forward of the fender vent directly in line with it. Tufts of various lengths of yarn hanging inside the fender gave me an indication of where the path of the greatest volume of air was being drawn from. The observation of the hanging yarn in the fender would help me design the inner structure I'll be making to smooth the flow of air into the opening again in an effort to move the largest volume of air without using electric fans.

My observations lead me to believe that the inner fender will not hinder the flow of air to the vent very much if at all if I do a good job designing the flow straightener. If we were discussing a liquid rather than a gas I suspect my findings would indicate a more direct path (which would be through the inner fender) from the core support to the vent would be more advantageous.

Cutting slots in the inner fenders would probably change under hood pressure conditions for the worse in my case by increasing pressure. I don't think the airflow through the engine compartment is hampered much by the inner hood structure and if it is it's probably not enough to justify the time, expense, or weight gain to smooth it.

 Glad your son's got an excuse to "test" the engine mounts haha. I've had a similar setup (the large center bolt) but mine were without the extra welds on the nut and the washer welded on.  I used them on the dragstrip 100+ passes, about 10 weekends on road courses, several weekend land speed races and about 15,000 miles street over about 12 years with no problems. I had less than 300 RWHP (dynoed) though, I'd really like someone with a manual trans and about 500 RWHP to try the new ones.

The stock mounts are pretty cheap but modifying takes quite a bit of time for setup on a drill press, drilling with various bits , countersinking, tapping, welding etc. If anyone asks you, they're $60.00 a set + shipping. USPS medium flat rate box is the cheapest in lower 48.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NY81TTASE on August 10, 2015, 05:02:14 PM
is it possible to try modifying the side vents so they work like a venturi vacuum? Maybe inside the fender area.  That way they will be pulling air out with out any moving parts. They are almost working in that manner anyway.   I wanted to do this under a car to the exhaust pipe,,to help pull exhaust through quicker.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 10, 2015, 09:43:29 PM
is it possible to try modifying the side vents so they work like a venturi vacuum? Maybe inside the fender area.  That way they will be pulling air out with out any moving parts. They are almost working in that manner anyway.   I wanted to do this under a car to the exhaust pipe,,to help pull exhaust through quicker.

This is what I have been doing. I'm trying to get the largest volume of air through the most constricted point which is shown by the black line in the pic below.  By modifying the exterior of the vent and making an inner structure to straighten the flow of air I'll hopefully be reducing turbulence while speeding up the air as it passes through the most constricted point (which you'd refer to as the venturi) with my goal being to try to move the largest volume of air through the vent in an effort to reduce lift in the engine compartment by reducing pressure.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/002_zpszsgmpfct.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/002_zpszsgmpfct.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 10, 2015, 10:54:36 PM
Vents look great!
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: skisix38off on August 11, 2015, 07:07:11 AM
Have you ventured onto Lateral-g.com or Pro-touring.com to read through some of the threads there?  Some of those guys are very involved in USCA racing and have 2nd gen F-bodies that are getting very fast.  Brian Hobough, Mike Dusold, Kyle Tucker, Brian Finch are some well known drivers that have these kinds of cars and they go very fast! 
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 11, 2015, 11:40:14 AM
Have you ventured onto Lateral-g.com or Pro-touring.com to read through some of the threads there?  Some of those guys are very involved in USCA racing and have 2nd gen F-bodies that are getting very fast.  Brian Hobough, Mike Dusold, Kyle Tucker, Brian Finch are some well known drivers that have these kinds of cars and they go very fast!

Oh ya, been an active member on those forums for years. I brought up my intent to modify the fender vents on the most active aero thread over there but got little/no useful responses. So I started tuft testing. Here's the thread which has the most useful information for musclecar era cars. Anyone interested in aero stuff should take the time to slowly read this thread from the beginning where Ron Sutton does a very good job of explaining a lot of the basics. http://www.pro-touring.com/threads/101460-Designing-Aerodynamics-for-Track-Performance

The aero stuff on the cars running the USCA are subject to the rules. So some of the things they do or don't do may be because of the rules. I'm not building to any particular set of rules so everything's game for me. Most of the things I'm doing aren't permanent so if I should decide I want to play by someone's rules I can change things. I'm a bang for the buck guy and always have to remember that I might stuff the car in a wall or ball it up on track so I'm cautious with what I'll invest in.

Speaking of wrecking the car reminds me..... Those of you who might follow Street Outlaws probably saw where Daddy Dave was building a new car. Wrecked, first outing https://www.youtube.com/watch?v=8_UIR-Ild4w

USCA? Oh boy, here we go! .....NOT A TA drags out soap box >>>>>>>>>>>

The top guys/gals running the USCA series have one common thing. LOTS of seat time. Most were already very very good drivers before the series even began. Other than tires Mary's car was set up almost exactly like mine running leaf springs and coil springs when she was winning the GG events around the country before the USCA got going. Why? Seat time. She was a seasoned SCCA autocross national champ for many many years.

The USCA has rules, which IMO are designed to promote the products offered by the companies promoting the series and limit the field to the type of vehicles who's owners are willing to spend the most money on parts offered by the companies promoting the series. I discussed the possible rules with Optima Jim and others involved back before the series began and I was foolishly thinking they were actually trying to find & expose some of the countries Ultimate Street Cars. I tried to get them to realize that certain rules they were considering would prevent a lot of guys like myself from showing up initially or in other cases forever. They didn't care, and the first years poor attendance reflected their decisions barely filling even half of the available positions. Now, because of promotion and the exposure the series has gotten, folks are building and modifying cars to be the most competitive within the rule set and fill rates have gone up. The bang for the buck guys will have a very hard time keeping up.

Here's one USCA rule example.

8. Tire rule - Participants must use commercially available, DOT approved, noncompetition,
treaded (non-grooved) street tires (no competition radials, no R compound,
drag radials or shaved tread) with a treadwear rating of 200 or higher. Tires will be
required to pass a technical inspection at the tech inspection. The spirit of the event
requires the use of a DOT approved “non-competition” tire – any modifications or
chemical treatments to tires will be unacceptable. Any vehicle with tires showing any
evidence of modification will be immediately disqualified from the event. Safety is of the
utmost importance and USCA officials will not hesitate to disqualify questionable tire
selections. Any tire not commercially available to the general public is prohibited.
9. Tire condition – Tires cannot show any signs of abuse, checking or obvious signs of
age or neglect. Tires must have a minimum of 2/32” tread depth at the start of the
event and must not show excessive wear. All entrants in the Intermediate or
Expert class must have tires with a manufacturer date within five (5) years of the
date of the OSUSC event being entered. Here’s how to check the date:
http://www.tirerack.com/tires/tiretech/techpage.jsp?techid=11
10. The use of any type of chemical or non-chemical treatment before or during the event is
strictly prohibited.
11. Participants must use a single set of tires for the entire event (including the road rally
segment); no tire changing between events will be allowed. Tires will be marked during
tech inspection. Tire changes will be allowed in the event of a catastrophic failure or for
safety related reasons as deemed necessary by USCA officials, but replacements must
be of the same size, manufacturer and model as those approved during tech inspection.


Now there are a lot of guys/gals around the country who drive their street cars to auto-X or road tracks events, bolt on auto-X, DOT-R, or slick tires, and run all day. Then they switch back to their street tires (all season radials) and drive home. They put track tires on because they don't overheat and get greasy which makes street tires MORE dangerous on track IMO. They may have full roll cages, fire systems, and fire suits with their car being prepared and tuned to use the specific type of tire that suits their purpose best. This is the same type of thing people have done with street/strip cars for decades switching to ET streets, drag radials, or drag slicks for the strip. A lot of these people (myself included) are not willing to purchase sets the best tires with a 200 TW rating which aren't as good (on track)as the tires normally used just to enter the USCA events. Switching tires to specific track tires is not only a way to optimize performance but IMO it's also safer because the tires are designed for that particular use. However USCA doesn't allow this common practice, but why?....

The rules quoted above require using one set of 200 TW or higher tires per event. Series sponsor Falken just happens to now have this tire available

AZENIS RT615K TIRE
Street-Legal Motorsports Performance and a DOT-Approved Track Tire

The AZENIS RT615K is a championship-winning street tire that is extremely popular for today’s sports cars, performance compacts and sedans. With its world-spec construction and advanced compound for street and track use, the RT615K confidently maintains grip both in street and track conditions. Through its proprietary technology, the motorsports inspired 8/32nd tread design and solid center rib provide significant traction and sustains strong grip in dry conditions. Available in 21 sizes from 14-inch to 18-inch, the RT615K is the track tire of choice with a UTQG rating of 200 A-A.


The tread wear rating is determined by the manufacturer with no control by any governing body so essentially they can say tire X is 400 TW or 200TW with no one checking or any penalties. Since the rules also push competitors to try and maximize the grip and life available from the one set of 200 TW tires they may be able to do that by running the widest tires they can fit and installing more sophisticated suspension systems. In our case with the F bodies perhaps something from USCA sponsor DSE will do?


Front Suspension - 1970-1981 F-Body - Hydroformed Subframe
    Additional Images:
   

        PDF ImageDownload and print
installation instructions here.   
Hydroformed Subframe

Detroit Speed’s front subframe is a bolt-in replacement for the original stock subframe. It improves the handling and ride quality by utilizing DSE’s unique suspension geometry. It is the ONLY subframe in the aftermarket industry with hydroformed frame rails. The hydroformed frame rails feature strength and stiffness, precise quality and repeatability. Hydroforming preserves the steel’s strength and stiffness because it is performed at low temperatures, unlike traditional high temperature processes which decrease material strength.
The subframe comes complete with the following components:
• Hydroformed Framerails
• Stamped Crossmembers
• Tubular Upper and Lower Control Arms
• DSE/JRi Coilover Shocks with 'Detroit Tuned' valving
• Torrington Bearings
• Coilover Springs
• 'Detroit Tuned' Power Rack and Pinion Steering
• Splined Anti-Roll Bar
• Forged DSE Spindle
• Spanner Tool for easy shock adjustments
• Composite Anti-Roll bar bushings
Up to a 10" wide wheel can be packaged without modification to the inner wheel wells. Both the main and secondary crossmembers are stamped for structural rigidity. SBC, BBC, LS1, LS2, and LS7 engines have been designed as a direct bolt-in into this subframe.
The DSE subframe has been designed, engineered, and developed for the road and track. This subframe blends the benefits of current OEM technology and aftermarket performance into one product!
The subframe is available uncoated and unassembled for your SBC, BBC, LS, or Pontiac engine. We also offer the subframe powdercoated satin black and assembled.
NOTE: Subframe must ship freight.

Note: Must use at least 17” wheels that require a minimum inside wheel diameter of 16.250".

 
Subframe in Bare Metal
 
Base Shock Options   Single Adjustable Options   Double Adjustable Options   Remote Canister Options

P/N: 032011
Applications: 1970-1981 F-Body
550lb/in SBC, LS
$7300.00
Add to cart   P/N: 032011S
Applications: 1970-1981 F-Body
550lb/in SBC, LS
$7750.00
Add to cart   P/N: 032011D
Applications: 1970-1981 F-Body
550lb/in SBC, LS
$8299.00
Add to cart   P/N: 032011R
Applications: 1970-1981 F-Body
550lb/in SBC, LS
$8600.00
Add to cart
            
P/N: 032012
Applications: 1970-1981 F-Body
650lb/in BBC, Pont.
$7300.00
Add to cart   P/N: 032012S
Applications: 1970-1981 F-Body
650lb/in BBC, Pont.
$7750.00
Add to cart   P/N: 032012D
Applications: 1970-1981 F-Body
650lb/in BBC, Pont.
$8299.00
Add to cart   P/N: 032012R
Applications: 1970-1981 F-Body
650lb/in BBC, Pont.
$8600.00
Add to cart
            
Subframe w/ Black Powdercoat & Assembly Option
 
Base Shock Options   Single Adjustable Options   Double Adjustable Options   Remote Canister Options

P/N: 032014
Applications: 1970-1981 F-Body
550lb/in SBC, LS
$7750.00
Add to cart   P/N: 032014S
Applications: 1970-1981 F-Body
550lb/in SBC, LS
$8200.00
Add to cart   P/N: 032014D
Applications: 1970-1981 F-Body
550lb/in SBC, LS
$8749.00
Add to cart   P/N: 032014R
Applications: 1970-1981 F-Body
550lb/in SBC, LS
$9050.00
Add to cart
            
P/N: 032015
Applications: 1970-1981 F-Body
650lb/in BBC, Pont.
$7750.00
Add to cart   P/N: 032015S
Applications: 1970-1981 F-Body
650lb/in BBC, Pont.
$8200.00
Add to cart   P/N: 032015D
Applications: 1970-1981 F-Body
650lb/in BBC, Pont.
$8749.00
Add to cart   P/N: 032015R
Applications: 1970-1981 F-Body
650lb/in BBC, Pont.
$9050.00
Add to cart
            
Available Upgrades:           
Severe Duty SKF Wheel Bearings
P/N: 032105
Applications: Hydoformed Subframe
$525.00

There are other rules that prevent cars from competing that could potentially steal the show because they out perform the cars the USCA desires to have attend. IMO it's because those cars owners aren't in the targeted "buying group". An example would be kit cars.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 11, 2015, 12:33:13 PM
Some of the tires rules make sense like coating them and the age and tread depth, but I don't understand why track tires or even D.O.T. competition tires aren't allowed on a RACE TRACK...  So from my understanding of the rules you're limited to ultra performance summer tires usually with a rating at best of 300 AA A?  I could get that if it were stock class or even a class that allowed certain mild modifications, but for full blown race car builds that's just stupid on so many levels...

I guess my dream of being an amateur race car driver will never happen then.  I don't even particularly care about being competitive, I just want to do it for fun.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 11, 2015, 10:10:58 PM
Some of the tires rules make sense like coating them and the age and tread depth, but I don't understand why track tires or even D.O.T. competition tires aren't allowed on a RACE TRACK...  So from my understanding of the rules you're limited to ultra performance summer tires usually with a rating at best of 300 AA A?  I could get that if it were stock class or even a class that allowed certain mild modifications, but for full blown race car builds that's just stupid on so many levels...

I guess my dream of being an amateur race car driver will never happen then.  I don't even particularly care about being competitive, I just want to do it for fun.

They're not full blown race cars, they're required to be registered, insured, etc.  However, to enter the fast class on the road course you need helmet, neck restraint, fire suit, 5 point or better race harnesses, and nomex gloves. To properly install 5 point harnesses you'll need a roll bar or harness bar, but you can only use 200 TW (or higher) tires.

There's lots of other things in the rules that seemed designed to bring a certain group of potential customers for products sold by the event sponsors to the events while preventing more competitive cars from entering. Full rules http://driveusca.com/wp-content/uploads/2013/12/USCARules_v9-3_2015_final.pdf

Because I'm a bang for the buck guy I run sticky DOT-R 40 TW tires. I wouldn't buy a set of 200 TW tires to attend an USCA event so I'll probably never attend one unless they hold one near me and I run the Exibition class just for fun with my regular tires. Their entry fees are expensive anyway so I could run 2 events with NASA or one of the other groups (which would give me a lot more track time) for the cost of an USCA event. Seat time is what I want.

Check into Kart racing in your area if you want to go entry level racing inexpensively.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 12, 2015, 12:58:56 AM
Yeah...the more I read through that the more I wouldn't want to deal with them, seems like they're self conflicting with what they say they're about and then what their rules are.

I know we have a few indoor kart tracks that do time attack racing, one even tunes the karts to the driver's' weight so everyone has a similar power to weight ratio.  Was thinking that might be a good starting point.  Skip Barber is actually like 25 miles away from my house but they're so expensive though.  That and if I end up keeping the '79 it'd need so much done with rims and tires, suspension, and brakes to be competitive.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: skisix38off on August 12, 2015, 07:02:24 AM
NOT A TA;
I just brought up USCA because those guys are running fast on some great tracks across america- they have to have some of the aero figured out and may have some information useful to you.

 FWIW- I'm a very average Joe and a newb when it comes to racing.  I have a mostly factory 78TA with Nitto 555, 300TW tires and I still have the rear drums on my car.  I'm not competitive in the USCA field and will never be because I don't have backing by major suppliers.

I drove in the TX USCA event this year and had a blast!  Best race event I've ever been to!  I understand a person not liking the rules of a particular series and requirements for this and that, maybe that's not a series for you.  I guess I don't see it like you do and would encourage anyone that races autocross to sign up for an event because they are fun and they provide some of the best seat time out there.  There will be guys out there with a ton of financial backing and there will be guys like me out there and we all mix together very well.  I'm not trying to alter your opinion about USCA, I'm not in love with that series either.  Just passing along my experience.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 12, 2015, 11:36:42 AM
Let me say. I applaud the USCA for providing events and getting folks out on tracks. Even if someone only goes to one event and never takes their car on track again it will be an experience they'll never forget.

Credit for the movement that brought about the USCA belongs to Bill Howelll IMO.  While I was on the PT forums inviting folks out to tracks and getting excuses Bill got them to walk first before trying to run.  He was the one who lead the transition of the Pro-Touring masses by getting them out of their lawn chairs and out driving their cars at his "Run To The" events at places like Tail Of the Dragon. As the RTT events evolved over several years he slowly incorporated road tracks into some of the events. Then as the evolution continued he started getting concerned about the lack of safety equipment being used combined with the lack of driver experience and enormous amount of power some of the cars had. He decided to step back and then the USCA was formed.


NOT A TA;
I just brought up USCA because those guys are running fast on some great tracks across america- they have to have some of the aero figured out and may have some information useful to you.

They may have some aero tricks, but if they do they're not being public about them. I'm sure most, if not all of them follow the aero thread on PT I linked previously. But they don't post in it. I suspect you'll see several of the things I'm going to do later in this thread will show up on some of the top USCA cars shortly thereafter or perhaps even before I get to it on my car since I've made my intentions public here and on other forums. If it reduces drag or increases downforce and is within the USCA rules someone will adopt it.

However their aero modifications are also (like tires) limited by the USCA rules. They can only change certain body things a certain amount. And, IMO while adding downforce would add grip it also adds more heat to tires not really up to the task (on the road courses) in the first place. I ran my car at Sebring one day with some 300 TW UHP tires and by mid session they were greasy to the point of under steering during corner entry and required a slow lap to cool back down. Adding down force to them would only speed up the overheating situation so I think the guys running up front at the USCA events are probably doing a bit of a balancing act already.

While the USCA is running events at some very nice venues there's locals that run street driven cars on those same tracks who would probably spank the top USCA guys with LS Miatas, LS RX 7's, Lotus Seven clones, and kit cars like the Factory Five GTM's Cobra's etc. nevermind all the Porsche, BMW and other marques hot street/track cars that the rules prohibit running in their current configuration.


 FWIW- I'm a very average Joe and a newb when it comes to racing.  I have a mostly factory 78TA with Nitto 555, 300TW tires and I still have the rear drums on my car.  I'm not competitive in the USCA field and will never be because I don't have backing by major suppliers.

Most types of amateur  "racing" come down to money. Those willing to spend the most time (including seat time) and money are in the top. The rest (like myself) are "also rans", "moto filler", or whatever you want to call us and are there for the experience and fun knowing we haven't got a snowball's chance of placing.

I drove in the TX USCA event this year and had a blast!  Best race event I've ever been to!  I understand a person not liking the rules of a particular series and requirements for this and that, maybe that's not a series for you.  I guess I don't see it like you do and would encourage anyone that races autocross to sign up for an event because they are fun and they provide some of the best seat time out there.  There will be guys out there with a ton of financial backing and there will be guys like me out there and we all mix together very well.  I'm not trying to alter your opinion about USCA, I'm not in love with that series either.  Just passing along my experience.

Getting out on a track is a blast and I encourage anyone who has the opportunity to do so. While the rules are cost prohibitive for my car I think anyone who can run an event the USCA puts on should try it.

There's a couple things that disappoint me with the USCA.  The first mostly comes from them calling it the Ultimate Street Car series while prohibiting many vehicles I would consider Ultimate Street Cars with their rules. The second is that by creating those rules they have limited the scope of what folks were doing and changed the direction of the evolution of Pro-Touring cars. They asked for opinions when forming the organization. Then pretty much ignored them in major areas and used input on smaller things like chemical tire prep.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 16, 2015, 10:04:38 PM
My more aerodynamic modified Barefoot vents are ready for primer.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/017_zpsgcyas4vf.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/017_zpsgcyas4vf.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/016_zpsmmzibtlh.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/016_zpsmmzibtlh.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/012_zpspubtl4xg.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/012_zpspubtl4xg.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/011_zpsfqls1v46.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zpsfqls1v46.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 16, 2015, 10:37:59 PM
Looks like might be able to reach through the vent now. :P
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: hakitup on August 16, 2015, 10:44:17 PM
That looks great!

Tom Ha
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 23, 2015, 09:02:58 AM
Looks like might be able to reach through the vent now. :P

Yes I can easily reach through the vent openings of the modified ones to put nuts on the studs that hold the vents. I will be putting different mounting studs in so I can attach a flow straightener inside the fender as the stock studs are too small for what I have in mind.

Below are a few pics of the modified vents. There's sooo much time invested in making them that they're staying as they are. I'm going to block them out for final paint and move on to other parts of the build. I'll do more tuft testing and probably pressure testing once the car is back on the road and I can see how they function in real world conditions.

I haven't forgotten about the shaker scoop discussion and have been writing my thoughts offline and will C&P it to post when I get it finished.

Stock, Barefoot, and Track Jack vents below.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/011_zps6u07qwkc.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zps6u07qwkc.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/013_zpst24ch5dm.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/013_zpst24ch5dm.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/012_zpsrh4zmoby.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/012_zpsrh4zmoby.jpg.html)

Track Jack below.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/018_zpsywajddeh.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/018_zpsywajddeh.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 23, 2015, 10:27:30 PM
Good work, they look great!
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: mrbandit on August 24, 2015, 06:46:58 AM
What material was the straighteners going to be made from?  Could you do plexi glass so you don't take away from the original look of your mod?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 24, 2015, 08:22:13 PM
What material was the straighteners going to be made from?  Could you do plexi glass so you don't take away from the original look of your mod?

I'll probably make them out of fiberglass since they'll be a weird shape resembling a contorted cornucopia.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 77 TA man on August 26, 2015, 09:03:50 PM
I know its not a Trans Am question, but how do the late 2nd gen Z/28s areo dynamics compare to a Trans Am?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 01, 2015, 07:48:36 PM
I know its not a Trans Am question, but how do the late 2nd gen Z/28s areo dynamics compare to a Trans Am?


The cars would be very similar as far as aerodynamics with the same basic shape. The Camaro rear spoiler ends provide more downforce. The Z-28's got the rear wheel flares by then and so the biggest difference would be the front end. I believe the birds were bottom feeders for air entering the radiator by then and the nose is a bit more cluttered on them than the Camaro. Overall they're probably about the same though.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 02, 2015, 09:37:49 AM
The next part of my aero project is making the front splitter, tray, and air dam extensions along with wickers for the wheel well flares. Cardboard & paper mock up for the road race track set up in the pic below below.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/011_zpsl6njwi3m.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zpsl6njwi3m.jpg.html)

The splitter/tray/air dam combination I've got in mind is a bit unusual from those I've seen on other cars.

A. Hinged to allow the splitter to be pushed up if I hit corner curbing or something. Splitter could rise till it hits the stock air dam. I've never whacked the stock air dam and I'll probably only loose maybe 1/2" ground clearance.

B. Two piece splitter/tray so I can have various splitters that stick out more or less with the biggest reaching out as far as the leading edge of the bumper and out as wide as the wickers on the wheel flares.

C. Height adjustable so I can use for street, LSR, Drag strip, road course, or open road with various height air dam extensions.

D. Various air dam extensions that will fold up if the splitter gets pushed up. Probably three versions, small for drag race & street , medium for road tracks, and a deep air dam extension  with minimal ground clearance for LSR with no splitter but supported from behind by the tray section.

E. Breakaway provisions so if something bad happens, damage to the car would be minimal and hopefully confined to the splash pan and stock air dam/wheel flares.

F.  Cheap/replaceable using as many pieces of scraps left from other projects and junk people gave me as I can. I gathered all the stuff I've been collecting and figured I could make something out of it even if just a prototype. It'll get the scraps out of my way and hopefully save me a few bucks.

While today lots of folks use CAD I still use DIG (Draw In Garage) for projects like this. Here's the basic concept drawing. The tray section the various splitters will be attached to has a smaller footprint than the stock air dam/wheel flare section.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/CCF08312015_0000_zps8uu4aohi.jpg) (http://"http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/CCF08312015_0000_zps8uu4aohi.jpg.html")
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1973klrbrd on September 02, 2015, 09:43:43 PM
John, love the DIG design. (Made me laugh)

First "Z07" option on a TA I've seen. Very cool. Are you or have you considering/ed side skirts or any underbody aero tricks for additional downforce? In addition, what s your opinion of incorporating brake cooling mechanisms into the aero design? You may already have this covered with other functional pieces I am unaware of but was curious. 
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 02, 2015, 10:35:56 PM
John, love the DIG design. (Made me laugh)

First "Z07" option on a TA I've seen. Very cool. Are you or have you considering/ed side skirts or any underbody aero tricks for additional downforce? In addition, what s your opinion of incorporating brake cooling mechanisms into the aero design? You may already have this covered with other functional pieces I am unaware of but was curious.

I've got better DIG diagrams I'll post up. There's a list of things I'm doing in the first post of this thread.

Side skirts, check.
Flat bottom, check.
Rear diffuser, check.

Pic below shows where I'm currently planning on pulling the air from for the brakes. Brake duct tube is here, need to fashion pieces to mount to the spindle. Will cover the brake ducts fully in a later post. Still debating on inline blowers.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/003_zps7h9kvapc.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003_zps7h9kvapc.jpg.html)

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 03, 2015, 09:24:19 PM
Here's some better DIG diagrams.

This shows how I plan on hanging the rear mount of the splitter to the frame. The height will be adjustable and the whole rear of the splitter will act as a giant piano hinge from fender flare to fender flare. The PVC listed at the bottom should have read 1/2" PVC pipe not 1".

Top two pics are side view and pic below is from front or back. I can MIG the steel pipe into the frame but need to find someone who can TIG the aluminum or figure out an alternative.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/CCF08312015_0001_zpsb9sraumt.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/CCF08312015_0001_zpsb9sraumt.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/CCF08312015_0002_zpswq3ibn30.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/CCF08312015_0002_zpswq3ibn30.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/CCF08312015_0004_zpsc6k0pjid.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/CCF08312015_0004_zpsc6k0pjid.jpg.html)

Pic below shows the mounting and adjustment of the support cables for the front of the splitter. No scale so proportions are all off. The cables will allow the splitter to rise if I hit a dip in the road/track or road course corner curbing. The splitter will come up and whack the bottom of the stock style air dam. I'll loose about 1 1/4" ground clearance compared with the stock air dam height but it may save the splitter.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/CCF08312015_0005_zpsudiqzohs.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/CCF08312015_0005_zpsudiqzohs.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 03, 2015, 09:40:16 PM
With the extremely accurate (chuckle, chuckle)  DIG diagrams to follow it's time to make this thing!

First step, get out some BIG pieces of cardboard to DIG on and cut up. I like appliance boxes. Sturdy, thick, and big.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/005_zpsc4k8cczr.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/005_zpsc4k8cczr.jpg.html)

I used another rough cardboard pattern I'd made before taking the car apart and along with more accurate measurements created a new cardboard version of what I wanted the whole splitter assembly to be shaped like when done. The leading edge is even with the nose of the car for the biggest version (for road courses). Then I started laying out a frame for the sturdy tray section that will be hidden behind the air dam. Most of this is being made with stuff I've had hanging around so although some materials may not be the lightest, or most applicable material it's cheaper and quicker if I just use what I've got and get it out of my way.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/007_zpsctwo6k0c.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsctwo6k0c.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 03, 2015, 10:05:55 PM
Since I want to have a 2 piece splitter so I can have different sizes I decided to Use sections of 1 1/4" box tubing I had for sections of the tray part so I could use 1" aluminum box tubing to slide into the 1 1/4" to align and support the rear of the front sections. 1" tubing into 1 1/4" tubing is kinda tight and too close of a tolerance for easy insertion /removal so I split the top side of the 1 1/4" and widened it a bit.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/008_zpswuhxwo0j.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpswuhxwo0j.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/003_zpsdj83hc8t.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003_zpsdj83hc8t.jpg.html)

Next I cut the sections of the cardboard apart to mock up the pieces that will connect them and keep them sturdy. The PVC pipe will go through the box tubing on the ears of the front section of the splitter and keep the two pieces joined while also being the pivot for the giant piano hinge at the rear of the splitter.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/001_zpskrutqunt.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001_zpskrutqunt.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 04, 2015, 09:02:09 AM
(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/001_zpsirxstnu6.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001_zpsirxstnu6.jpg.html)

Seen in the pic above is a large sheet of 14 gauge aluminum a buddy gave me that came out of some kind of large blueprint machine or something. Perfect for the tray section of my splitter but too short to make the whole splitter out of it even if I wanted to which I didn't. So I cut it up and taped all the box tubing in place.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/002_zpsbwtcs4cm.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/002_zpsbwtcs4cm.jpg.html)

The pics below show how the engine tray will also be attached to the piano hinge at the rear of the splitter tray and a bracr for the sheet aluminum will be used to support the aluminum sheet in front of the engin pan notch.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/003_zpsmzbk8yoi.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003_zpsmzbk8yoi.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/005_zpszp85qzqt.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/005_zpszp85qzqt.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 04, 2015, 09:15:31 AM
I had most of a sheet of hardboard (really inexpensive stuff) left from making a rear package tray for my Malibu so I figured it'd make a great pattern to use (and keep for future use if replacement front sections are needed) for the various size front sections. Using the DIG cardboard pattern I transferred and cut. This will be strong enough and stiff enough to mock up the attachment pieces and front supports more easily than cardboard and I'll have the piece left over as a future pattern.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/006_zpsvbvpkv9t.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/006_zpsvbvpkv9t.jpg.html)

Searching around for something with the right curve to make a nice corner for the leading edge of the splitter I decided on a 74 Jensen Healey wheel (anyone wanting to buy a set let me know) . Started with my coffee cup and kept finding bigger things. Thought it'd make a cool pic to see the various things I'd considered using.
(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/007_zpsztb2bndo.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsztb2bndo.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: mrbandit on September 04, 2015, 09:20:25 AM
Can you use an actual flare to get the correct curve?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 04, 2015, 09:28:19 AM
The curve I was making is for the leading edge of the splitter under the headlight. It will be changed again later anyway since I made the hardboard template oversize in width so it can be trimmed later to the width of the outside edge of the wheel well wickers that stick out past the wheel flares. I'm not sure exactly how far out I'll have the wickers stick out so I planned ahead by just making the splitter pattern extra wide.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 04, 2015, 09:37:27 AM
Mocking up the pieces in pics below. The white vertical PVC pipe is slid through the holes in the frame where the steel and aluminum pipes will be mounted to support and provide height adjustment for the splitter. The PVC will NOT be used to support the weight. They're just in the frame so I can line things up and measure.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/008_zpsd1dqu8kc.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpsd1dqu8kc.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/010_zpsvl8r0t1d.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/010_zpsvl8r0t1d.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/004_zpsv7mgjo4t.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zpsv7mgjo4t.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 04, 2015, 09:47:48 AM
In previous pics you've seen bicycle spokes in the positions I want the supports for the front of the spoiler. They will be made with turnbuckles and steel cable lanyards (made to suit) so I can fine tune the height and angle of the splitter while allowing the splitter to raise up hinging on the giant piano hinge if the leading edge of the splitter hits the ground. I'll be sourcing something similar to the plastic rails used on the bottom sides of skateboards in the 80's to be attached under the leading edge of the splitter to take the abuse should the splitter touch the road surface.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/013_zpsqonzbgbm.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/013_zpsqonzbgbm.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 04, 2015, 09:58:20 AM
So now I wait to receive some pieces I need to complete this from McMaster (aluminum pipe and fittings)and need to decide exactly what material I will use for the front sections of the splitter. Meanwhile I've got plenty of things to work on. Patterns for smaller versions of the splitter, plastic air dam extensions, and wickers for the wheel flares are at the top of my "to do" list. Will post them once I've got something worthwhile to show. Final assembly of the splitter will be done later when I have all the pieces ready to bond, rivet, weld, and bolt together.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on September 04, 2015, 10:15:36 AM
I've always thought it would look better if the bottom lip and flares were flush with the face of the car instead of sitting back.  Looks better and functional, hard to argue with that.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 04, 2015, 08:29:25 PM
I've always thought it would look better if the bottom lip and flares were flush with the face of the car instead of sitting back.  Looks better and functional, hard to argue with that.

Here's one of the other front sections. Being smaller it looks a little less like an all out race car or caricature to  me.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/003_zpsmphbwku9.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003_zpsmphbwku9.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 08, 2015, 10:35:26 AM
I mocked up a flow straightener for the fender vents. Although the pieces would work well for a car with only one set of modified vents (purpose built race car) I'm not thrilled with the design for my particular application where I'll be switching among 3 sets of fender vents. As pictured below they would require that the vent be installed in the fender, then the flow straightener installed, and then the inner fender be put in. I don't want to remove the inner fender to switch fender vents every time and I don't want to spend the time finding a way to modify things to use a different type of vent installation fastening system. I considered something like the pop on headlight fasteners new cars use but that modification, combined with making the flow straighteners, is more time than I want to spend on this now. Perhaps at a later point I'll try one of the other flow straightener designs I've considered. Right now I need to move on with the build in general and not get too bogged down with any one thing.

I figured I'd post this up for anyone wanting to build something similar. I do feel it would increase air speed through the fender vent thereby evacuating a larger volume of air in the same time period compared with just a vent without flow straightener. If this was for a race only application I'd use it.

A short radius to smooth the fastest moving air is at the top of the vent inside the fender. Air (coming over the inner fender inside the fender) will be pulled from the top inside the fender (reducing lift) and air flowing from the main engine compartment area would speed up flowing to the vent past a gentle radius at the rear by the firewall (due to reduced turbulence).

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/039_zpslxtidpfh.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/039_zpslxtidpfh.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/033_zpsivcgn153.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/033_zpsivcgn153.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/021_zpsackslcmz.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/021_zpsackslcmz.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: jonathonar89 on September 08, 2015, 01:09:21 PM
Great work and innovative ideas John!
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1973klrbrd on September 21, 2015, 11:55:56 AM
Very cool fender vents John. This is a great thread you have going. A bunch of innovative ideas at work here. Thanks for sharing. 
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 22, 2015, 07:45:49 AM
Thanks guys!

Jay, can you post up some pics of your splitter? Height from track surface? Mounting? Experiences?

Here's the hinged splitter I'm going to test. If it works out well I'll make a nicer version with different materials that's prettier. In the pics below the car is set up (with no front springs) as if it were in full dive under threshold braking smashing the bump stops. The bottom of the tip of the splitter is 1 1/4" above the track surface. I'll loose another 5/8" or so for rub strips I'll be putting underneath the leading edge.

There is 4" upward travel at the tip and 2" travel where the tip of the original spoiler is. So if this hinging thing works, in theory I could drive over a ball about an inch in diameter smaller than I could without the splitter. 3/8" for the plywood and about 5/8" for the rub strips. If I have to use solid splitter supports I'll loose 3" + where the tip of the original splitter is plus whatever is lost because the splitter sticks out so far.

The cables are strong. With only the two center cables attached I'm able to stand on the tip of the splitter.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/008_zpslg5kzsnr.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpslg5kzsnr.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/004_zpsksroqlgy.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zpsksroqlgy.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/008_zpsk0eex38g.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpsk0eex38g.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/007_zps91ms5mvr.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zps91ms5mvr.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/009_zpsbktv5ixa.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/009_zpsbktv5ixa.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 22, 2015, 08:30:36 AM
While waiting on materials for the splitter I got busy making the brake cooling duct backing plates for the brake rotors. The Baer 14" set up for 2nd gen F bodies includes a new spindle which has a speed sensor mount cast into it. The speed sensor mount is right where I wanted to put the brake duct hose so it had to be removed.

The backing plates for the rotors are just a bit smaller than the rotor hat and fit almost flush inside the rotor hat when mounted. This creates a pressurized plenum of cool air to flow through hat and then the vents in the rotors. Without the backing plates hot air that's passed over the outside of the rotors would be mixed with the cool air from the ducts before entering (or re-entering) the rotor hat and still wouldn't be forced through the rotor vents relying only on the vent design to pull air into the hat as the wheel turns. Without any modifications almost half of the rotor hat area is blocked by the spindle and caliper bracket/abutments. The whole thing is shrouded by the smallest diameter (18") and widest tire (285) I can fit. Pressurizing the hat with cool air will also help keep bearing temps down.

The Baer spindle is fully assembled and adjusted with hub, calipers, rotor, pads etc.and is ready to bolt on out of the box (which I did initially). To install the brake ducts everything had to come apart to make the backing plate for the spindle. In the pic below the spindle is bare and the speed sensor mount is still in place. You'll see in following pics the speed sensor mount is gone.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/001_zpsrjoqy6rx.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001_zpsrjoqy6rx.jpg.html)

the white line in the pic below shows the size of the rotor hat. As you can see a lot of it is blocked off by the caliper brackets etc. even though the speed sensor mount is gone.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/013_zps1aslc5cq.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/013_zps1aslc5cq.jpg.html)

Pic below shows how the backing plate fits into the rotor hat.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/011_zpsoydfulit.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zpsoydfulit.jpg.html)

Hose routing below checking for steering and suspension interference. It's a tight fit so actual track testing may lead to changes.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/015_zpsgndwxbh0.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/015_zpsgndwxbh0.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/014_zpsks4vfsyb.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/014_zpsks4vfsyb.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/016_zps81sxtw1o.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/016_zps81sxtw1o.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: RatOne on September 22, 2015, 08:52:44 PM
Looks great!  Looking at your pics It makes me wonder if the c5 z06 brake ducts would retrofit on the trans am?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1973klrbrd on September 23, 2015, 06:24:23 AM
John, this is great stuff. Informative as well. Where did you research all the info about the brake ducts. I look forward to reading your next update.

Here is a few pics of the splitter. They are not great detail. I need to get into my photo archives fro the TA build to find more detailed fab and build photos.

Finished look. Couple angles. It is not nearly as adjustable as your design. We get approximately 3/4" - 1" of adjustment from the turn buckles so typically the splitter is left in place as you see it in the pic. Plus, the splitter does not do a whole lot for aero on autocross which is where my wife enjoys driving the car the most.

(http://i1372.photobucket.com/albums/ag340/Jdeluca/imagejpg8_zpsa097f0ed.jpg) (http://s1372.photobucket.com/user/Jdeluca/media/imagejpg8_zpsa097f0ed.jpg.html)

(http://i1372.photobucket.com/albums/ag340/Jdeluca/imagejpg5_zps8e826040.jpg) (http://s1372.photobucket.com/user/Jdeluca/media/imagejpg5_zps8e826040.jpg.html)

Pic of the splitter fitment to the front flare.
(http://i1372.photobucket.com/albums/ag340/Jdeluca/AD7759FC-BCE9-4A62-9E79-DAB4219B2F76_zpsakeuulry.jpg) (http://s1372.photobucket.com/user/Jdeluca/media/AD7759FC-BCE9-4A62-9E79-DAB4219B2F76_zpsakeuulry.jpg.html)

I do not have any good detail dimensional pics like yours John, yet you can see from this photo, we have 3-4" of ground clearance at speed and in the neighborhood of 2-3" at full brake.
(http://i1372.photobucket.com/albums/ag340/Jdeluca/DSC_0849_zpslt69cw7p.jpg) (http://s1372.photobucket.com/user/Jdeluca/media/DSC_0849_zpslt69cw7p.jpg.html)

I need to go back through my photo archives to find more detailed build pics of the splitter. If I can track them down I'll post a couple up. The install was fairly simple and not nearly as functional as your design from a racing need. The design we installed does add downforce on the nose at speeds over 100mph but we rarely are getting the car above those speeds these days.   
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: doubleclutch on September 23, 2015, 07:53:50 PM
This is one of the coolest posts I've ever seen. My goal is autocross, so I'm digging all of the race tech.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 23, 2015, 09:45:11 PM
Jay, I think your splitter probably helps more on auto X courses than you realize. It's certainly cool looking and blends well with the car better than mine which looks like a fat lip. ahaha

I'd like to see the bottom of it and how it's attached.

EDIT: You have a PM.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 23, 2015, 09:51:54 PM
This is one of the coolest posts I've ever seen. My goal is autocross, so I'm digging all of the race tech.

Glad you like it! Keep checking in for new info and if you try anything on your own car or have questions just ask. We'll be discussing the later 2nd gens and the aero differences between early and late cars very soon.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 27, 2015, 09:15:41 PM
One of the ways to reduce the under hood air pressure that causes lift is to limit the air entering. I'm sealing the core support so the only air that passes through is for radiator cooling and brake cooling.

The cavity behind the bumper in front of the core support has a higher air pressure at speed than the engine compartment. Because the whole cavity becomes pressurized the air tries to find a way to get to the lower pressure area behind the core support. As built, there's a gap on the sides of the core support and between the top of the core support and the hood. The faster the car goes the higher the air pressure becomes in front of the core support and it finds it's way around the core support which raises the air pressure under hood. This is one of the factors that contributes to "float" experienced in a lot of cars at high speeds. The higher the air pressure raises under the hood the less grip the tires have so we want to keep the unwanted air from getting under the hood. For high speed Auto X and road course activities we want all the traction on corner turn in we can get.

Adding a splitter to reduce the airflow under the car and increase down force also increases air pressure in the cavity by stacking up more air in front of the car which increases the air pressure in the cavity in front of the core support.

Here's what I'm doing to limit air from entering the engine compartment by sneaking around the core support. The idea is simple rubber flaps pop riveted to the core support in such a way that as pressure in the cavity increases the air pressure pushes the rubber flaps tighter against the inside of the fenders and other sheet metal creating a better seal so the faster you go the tighter the seal. Unless, the speed increases the pressure soo much that the seal blows back, in which I'll replace with thicker stiffer rubber.

In the pic below you can see how much open space there is for air to get past the core support on the sides. The white areas are where air can normally pass through between the core support and fender as well as the large hole the bumper supports/frame pass through.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/007_zpsojalgcdf.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsojalgcdf.jpg.html)

Pic below shows how flat rubber sheet  is used to block the air. Will be pop riveted in place before fenders are installed during final assembly. The rubber will be trimmed a bit more after install around the side marker light and slots will be cut where the headlight wiring etc. needs to pass through.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/008_zpstrvjcbx5.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpstrvjcbx5.jpg.html)

Pics below shows how the bumper support hole is sealed. I'd considered trying to use the frame itself for the brake duct like a lot of the 4th gen track guys do but after examining it carefully decided it was easier to just run brake duct hose on my 2nd gen.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/021_zpst8lneu5k.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/021_zpst8lneu5k.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/013_zpskxnpw0zj.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/013_zpskxnpw0zj.jpg.html)

A lot of air can go over the top of the core support inside the fender. First pic below is from the front and second shows seal placement on the backside.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/011_zpsyeou08ma.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zpsyeou08ma.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/012_zpszgkenssp.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/012_zpszgkenssp.jpg.html)

There's a gap between the top of the core support and the underside of the hood. It's over 55 sq. in. that air can easily pass through so I want it sealed. A 2" strip of rubber across the width of the hood solves that problem!

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/016_zpsmxeg5qck.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/016_zpsmxeg5qck.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/015_zpsusmrg2ze.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/015_zpsusmrg2ze.jpg.html)


Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 28, 2015, 10:09:53 PM
I'm going to ramble a bit about things that are relevant to posts coming up.

As mentioned in my last post the air pressure in front of the core support is higher than the air pressure in the engine compartment when the car is moving. Besides reducing lift, another reason for sealing off the core support so the least amount of air can get around it is so that we can create the biggest difference in pressure possible to aid engine cooling. The greater the difference in pressure the easier it is to cool the radiator because the air in front is trying harder to pass through the radiator to get to the low pressure area regardless of fans or shrouds. By creating a pressure difference between the front and back of the radiator the air is being forced/sucked through the radiator as long as the car is moving.

Conversely the higher the air pressure is in the engine compartment the harder it is for the fan to create a pressure difference which draws air through the radiator. This is why there is an air dam under the core support of many cars even though they're not considered performance cars. The air dam increases the difference between the air pressure in front of the radiator and behind it when the car is moving. The simple style air dams were used on regular Firebirds during the later years of the 2nd generation.

With a good difference in air pressure between the front and in back of the radiator a fan isn't really needed, the air will flow through naturally on it's own. A fan just creates a lower pressure behind the radiator which causes air to pass through the radiator trying to equalize the pressure. In our 2nd gen birds a thermal clutch fan was used on most models which allows the fan to just freewheel at highway speeds when there is enough of a pressure difference front to back of the radiator causing enough air flow to cool the radiator. The bimetal coil on the clutch that causes the clutch fluid changes which engage and disengage the fan operation senses that the radiator is being cooled enough and the fan freewheels. The clutch fan saves gas, reduces fan noise, etc. Remove the TA air dam or the small air dam used on the late 2nd gen birds and Formys and the clutch fan will keep the fan engaged at higher speeds than with the air dam in place because the smaller difference in pressure between the front and back of the radiator (without the dam) will reduce airflow through the radiator at a given speed. Thermal clutch fan explanation here http://www.howstuffinmycarworks.com/Fan_clutch.html

Increases in engine power also require an increase in cooling because increased heat is a byproduct of increased power. So often times the first thought is to use an aluminum radiator and an electric fan(s) to deal with the additional heat generated by a more powerful engine combination. Makes sense right? Engine temps still too high? Use a bigger fan or maybe a two speed fan, and if that doesn't work step up to twin fans and perhaps a larger core radiator. Still can't cool the radiator enough? Try an additional pusher fan in front of the radiator also... I've seen many people go through this scenario when their problem isn't really a mechanical one it's an aerodynamic one. What they need is a bigger difference in air pressure between the front and back of the radiator and other factors are causing the air pressure in the engine compartment to be so high that the fans have a tough time creating a big enough pressure difference in front/back of the radiator to get enough airflow to properly cool the radiator. The air pressure under hood is so high it prevents the fan(s) from functioning well. This is often caused by modifications someone has done to the car without realizing the additional consequences of the modification other than what was originally intended.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 29, 2015, 04:02:17 PM
So one might wonder what kinds of modifications would increase the air pressure under the hood of a 2nd gen?

Adding a transmission or oil cooler to one or both sides of the radiator by cutting a hole in the core support next to the original radiator opening.

Swapping to headers that might change the airflow under the engine by slowing it down with all the tubing before the collector and hanging lower than the stock exhaust.

Inner fender removal.

Removing or not replacing deteriorated "splash guards" on the inner fenders around the upper control arm.

Installing a radiator that doesn't fit quite as well as the original leaving gaps on the side or top between the radiator and the core support.. This happens pretty often with aftermarket aluminum radiators that aren't "exact fit" but rather "fits most" and are sold by core dimensions and inlet/outlet size.

Deteriorated or removed shaker seal to hood.

Open shaker scoops that are strapped to the hood with nothing to seal them below. Most often used with an open aftermarket air filter.

Open Formula hood scoops that aren't used with a Formy air cleaner base.

Low hanging aftermarket oil pans.

Low hanging remote oil filters or oil coolers.

Aftermarket dual exhaust mufflers under the front floor pans that hang down blocking air flowing under the car.

Aftermarket cowl induction hoods without using a carb pan that seals to the hood when it's closed.

Aftermarket forward facing hood scoops without using a carb pan that seals them.

Deteriorated or missing cowl to hood seal.

Deteriorated or missing inner fender extensions.

Now I'll be the first to admit I've done a few of these things in the past. The worst was removing the shaker scoop completely on certain road tracks because it blocked my view and I couldn't see the apex of certain corners at Road Atlanta and Sebring. And guess what? Engine temps were higher to the point that on one hot day at Sebring  I had to run the heater full blast on high while on track  plus take a slow lap in the middle of each 20 minute session to cool down the engine. Eventually I made a seat pad to raise me up a bit so I don't need to remove the scoop.

Many of the things mentioned above also reduce performance in other ways besides making it harder for the radiator to cool the engine.

Pic in the pits at Sebring. Note missing shaker and the hood open a bit to help the car cool between sessions.

(http://i240.photobucket.com/albums/ff292/NOTATA/Sebring%2009/Sebring620-21024.jpg) (http://s240.photobucket.com/user/NOTATA/media/Sebring%2009/Sebring620-21024.jpg.html)

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 29, 2015, 06:00:00 PM
Moving along,  Jay "1973klrbrd" has consented to allow me to use his and Amy's car (seen above) as a sort of case study here. Although I've never seen it in person I've known about it and followed it for many years from the beginning when Albert the owner of Carbon Kustoms created it. The car is a great example of a beautiful top pro touring car with lots of modifications to the body, drive line, and suspension. The modifications have increased the speed and mechanical grip available making it a much more capable car than it was stock. I suspect,  (based on what I've seen in pics) that a few aerodynamic changes could make it even more competitive at PT events.

The PT cars have gotten very advanced the past few years and there are now competitive events for them to run at. With the competition all maximizing the power and suspensions available and the rules that set limits on things like tire tread wear ratings I think we'll see more efforts to use aerodynamics to increase grip. The 2nd gen birds are a natural for these types of competition because they have advantages right from the start compared with a lot of other models of muscle car era cars.

When Albert built this car he was concentrating on the prototyping and eventual production of Carbon Fiber hoods, fenders, shakers, inner fenders and other parts to lighten the cars. I for one would love to have some of the pieces for my own car, but I digress. I noticed that there were a couple things I thought should have been retained or better modern versions of made that were (are?) missing that are key aerodynamic parts. In particular there was no cowl seal or inner fender splash guards.

(http://i240.photobucket.com/albums/ff292/NOTATA/BC8A4822-491D-424E-9494-B75B07235558_zpsbsnzsmxq.jpg) (http://s240.photobucket.com/user/NOTATA/media/BC8A4822-491D-424E-9494-B75B07235558_zpsbsnzsmxq.jpg.html)

Both parts help keep under hood air pressure down and in so doing make the car stick better. The splash guards reduce the amount of air that can get in from the high pressure area in the wheel well. It can't be actually sealed off very easily but simple splash guards would reduce the volume of air that can get in.

The cowl to hood seal is actually a much bigger deal because the air pressure at the base of the windshield is very high. That air is being forced under the rear edge of the hood and moving forward entering the engine compartment because the seal is missing. Many folks think of the seal as a weatherstrip to keep water in the cowl area (and out of the engine compartment) so it will go down the cowl openings and drain out, however it's main function I believe is to keep high pressure air from entering the engine compartment. Lots of people don't replace the cowl seal because they aren't planning on driving in rain or using a hose to wash the car and the cars are now toy cars that spend most of their time in a garage. However that's not the main purpose of the seal.

The hood doesn't have the grills in it like a regular 70-76 hood (will talk more about the hood grills later) so the full force of the highest pressure air at the windshield base is forced into the engine compartment. This increases the air pressure under the hood increasing lift at speed (less front wheel grip), making it harder for the radiator to be cooled, and adding a large volume of air which needs to escape the engine compartment. Since most of the air will go out under the car it will increase lift under the car and as speed increases the rear wheels will have less grip. I suspected that at high speeds the rear was "light" and the car had a tendency to over steer.  Then I saw this pic which leads me to believe I might have been right.

(http://i240.photobucket.com/albums/ff292/NOTATA/2nhnapv_zpspwcatoct.jpg) (http://s240.photobucket.com/user/NOTATA/media/2nhnapv_zpspwcatoct.jpg.html)

The addition of a splitter on the front of the car may have exaggerated the effect because it's forcing the front end down while cantilevered (tipping the rear up) and the air being blocked by the splitter is being replaced by the air coming into the engine compartment from the cowl. While at lower auto X speeds the splitter may be helping it may be hurting at very high speeds. My guess is that at high speeds over 100 MPH the rear has less grip than it should for gentle sweepers, when threshold braking, and also during initial turn in at the end of high speed straightaways on road tracks the rear probably wants to slide out. If an effective cowl seal can be used I'd bet the bias valve for the rear brakes could be adjusted to add more bite on the rear calipers and there would be better overall braking with less dive. This would shorten braking distances and make initial turn in on high speed corners at the end of straights smoother (including auto X). Smooth = fast.





Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 29, 2015, 07:20:42 PM
The 70-76 hoods had grills in them above the openings in the top of the cowl but 77 & up hoods do not have the grills. All of the aftermarket fiberglass 70-76 hoods I've seen exclude the grills.

The grills in the early stock style hoods allow the air pressure above and below to remain more equalized as the air pressure increases with speed. If there is a good cowl seal on the car the hood remains as we think it should. If there's an aftermarket  hood without grills used and the seal is good the hood may start to vibrate, burping the high pressure air built up under the hood above the cowl into the engine compartment. This is because the highest pressure air closest to the windshield at the base is being forced under the rear of the hood and the air pressure above the hood is lower allowing the hood to be pushed up.

The 77 and up hoods have no grills in them. But why? Perhaps because of the national 55 MPH speed limit in effect at the time and the manufacturing cost of the grills which might not be needed at 55 MPH. In any case I've seen the later hoods pushed up by air pressure at high speeds. I don't know of a simple long term cure other than hood pins to hold the rear of the hoods without grills. I'm sure many of you have done like I do and push the rear of the hood down after highway use or high speed runs. However if the hood gets pushed up and air enters the engine compartment it increases lift etc.so for high speed activities we want the hood to stay down and the engine compartment sealed off. I have seen some guys use 2" square spongy foam to keep the cowl sealed on the 77+ cars during high speed race events. They just lay it across the cowl and shut the hood.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 29, 2015, 07:41:08 PM
Some of you may have wondered how much of a difference sealing off the top, sides, etc. of the core support could really make. The surface area of the gaps blocked off adds up to over 1/3 the size of the radiator opening so it's like having a hole this big in the core support allowing air directly into the engine compartment.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/004_zps0p3djf7f.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zps0p3djf7f.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1973klrbrd on September 30, 2015, 10:30:08 AM
I've always thought it would look better if the bottom lip and flares were flush with the face of the car instead of sitting back.  Looks better and functional, hard to argue with that.

Here's one of the other front sections. Being smaller it looks a little less like an all out race car or caricature to  me.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/003_zpsmphbwku9.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003_zpsmphbwku9.jpg.html)

John, this is a great look for the splitter. Have n idea what the downforce or aero needs you are seeking will be with this design, but aesthetically, this is way cool.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: mrbandit on September 30, 2015, 02:21:18 PM
Wow John, this is excellent information.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 30, 2015, 08:34:31 PM
Thanks guys! I forgot about this pic I'd intended on posting early in this thread. Think it came from Pontiac back in the day. Note the blurb about the fender air extractors.

(http://i240.photobucket.com/albums/ff292/NOTATA/airdams_zps5r3pl20o.jpg) (http://s240.photobucket.com/user/NOTATA/media/airdams_zps5r3pl20o.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 30, 2015, 08:54:42 PM
I decided to go ahead and pop rivet the core support seals in place since the core support is already painted and then I won't have to keep track of all the rubber panels. So here's a couple pics before and after.

Upper fender above core support before/after.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/008_zpsogxtjqrc.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/008_zpsogxtjqrc.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/010_zpslkdr0i3b.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/010_zpslkdr0i3b.jpg.html)

Drivers side fender to core support gap before/after rear, after front. Note the hole around the frame/bumper support in the first after pic.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/012_zpsrgnovkjv.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/012_zpsrgnovkjv.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/016_zpsfeey0euo.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/016_zpsfeey0euo.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/020_zps9x6ke6rd.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/020_zps9x6ke6rd.jpg.html)

Frame/bumper support seal.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/023_zpsyb1jqclo.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/023_zpsyb1jqclo.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 30, 2015, 09:14:24 PM
At Land Speed Races you'll often see cars with all the body seams taped up like the pic below. Rumor has it that little things that reduce drag will allow slightly higher top speeds.

(http://i240.photobucket.com/albums/ff292/NOTATA/LSR%20Everglades%20oct%2009/milemarker-1005.jpg) (http://s240.photobucket.com/user/NOTATA/media/LSR%20Everglades%20oct%2009/milemarker-1005.jpg.html)

I'm a long way from getting to the point that tape is going to make much difference on my cars top speed and I think it looks funny.  I'm going to use a wiper seal on the sides of my hood with the hope it keeps high pressure air from entering the engine compartment and reduces turbulence a little even if I can't quantify a difference.

This is a little piece of the seal I'm using and in the second pic you can see how it seals to the fender. There will be a couple breaks in the seal for the hood side bumpers which will be retained but the seal will butt up to the bumpers so there's no air gap to speak of.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/001_zpsf0zprnnw.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/001_zpsf0zprnnw.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/007_zpsyiclhspx.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsyiclhspx.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 30, 2015, 09:30:22 PM
While hunting through my Photobucket  for a taped up car I was reminded of what happened at a LSR I was at. Killer corvette with a custom intake that required a custom raised center section hood. Got up to a certain speed and the high pressure air from the windshield base raised the hood and blew it off at well over 150 MPH. Didn't have a functional cowl seal as you can see in the lower pic.

(http://i240.photobucket.com/albums/ff292/NOTATA/LSR%20Everglades%20oct%2009/mm1087.jpg) (http://s240.photobucket.com/user/NOTATA/media/LSR%20Everglades%20oct%2009/mm1087.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/LSR%20Everglades%20oct%2009/mm1077.jpg) (http://s240.photobucket.com/user/NOTATA/media/LSR%20Everglades%20oct%2009/mm1077.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1973klrbrd on October 01, 2015, 03:00:44 PM
Moving along,  Jay "1973klrbrd" has consented to allow me to use his and Amy's car (seen above) as a sort of case study here. Although I've never seen it in person I've known about it and followed it for many years from the beginning when Albert the owner of Carbon Kustoms created it. The car is a great example of a beautiful top pro touring car with lots of modifications to the body, drive line, and suspension. The modifications have increased the speed and mechanical grip available making it a much more capable car than it was stock. I suspect,  (based on what I've seen in pics) that a few aerodynamic changes could make it even more competitive at PT events.

The PT cars have gotten very advanced the past few years and there are now competitive events for them to run at. With the competition all maximizing the power and suspensions available and the rules that set limits on things like tire tread wear ratings I think we'll see more efforts to use aerodynamics to increase grip. The 2nd gen birds are a natural for these types of competition because they have advantages right from the start compared with a lot of other models of muscle car era cars.

When Albert built this car he was concentrating on the prototyping and eventual production of Carbon Fiber hoods, fenders, shakers, inner fenders and other parts to lighten the cars. I for one would love to have some of the pieces for my own car, but I digress. I noticed that there were a couple things I thought should have been retained or better modern versions of made that were (are?) missing that are key aerodynamic parts. In particular there was no cowl seal or inner fender splash guards.

(http://i240.photobucket.com/albums/ff292/NOTATA/BC8A4822-491D-424E-9494-B75B07235558_zpsbsnzsmxq.jpg) (http://s240.photobucket.com/user/NOTATA/media/BC8A4822-491D-424E-9494-B75B07235558_zpsbsnzsmxq.jpg.html)

Both parts help keep under hood air pressure down and in so doing make the car stick better. The splash guards reduce the amount of air that can get in from the high pressure area in the wheel well. It can't be actually sealed off very easily but simple splash guards would reduce the volume of air that can get in.

The cowl to hood seal is actually a much bigger deal because the air pressure at the base of the windshield is very high. That air is being forced under the rear edge of the hood and moving forward entering the engine compartment because the seal is missing. Many folks think of the seal as a weatherstrip to keep water in the cowl area (and out of the engine compartment) so it will go down the cowl openings and drain out, however it's main function I believe is to keep high pressure air from entering the engine compartment. Lots of people don't replace the cowl seal because they aren't planning on driving in rain or using a hose to wash the car and the cars are now toy cars that spend most of their time in a garage. However that's not the main purpose of the seal.

The hood doesn't have the grills in it like a regular 70-76 hood (will talk more about the hood grills later) so the full force of the highest pressure air at the windshield base is forced into the engine compartment. This increases the air pressure under the hood increasing lift at speed (less front wheel grip), making it harder for the radiator to be cooled, and adding a large volume of air which needs to escape the engine compartment. Since most of the air will go out under the car it will increase lift under the car and as speed increases the rear wheels will have less grip. I suspected that at high speeds the rear was "light" and the car had a tendency to over steer.  Then I saw this pic which leads me to believe I might have been right.

(http://i240.photobucket.com/albums/ff292/NOTATA/2nhnapv_zpspwcatoct.jpg) (http://s240.photobucket.com/user/NOTATA/media/2nhnapv_zpspwcatoct.jpg.html)

The addition of a splitter on the front of the car may have exaggerated the effect because it's forcing the front end down while cantilevered (tipping the rear up) and the air being blocked by the splitter is being replaced by the air coming into the engine compartment from the cowl. While at lower auto X speeds the splitter may be helping it may be hurting at very high speeds. My guess is that at high speeds over 100 MPH the rear has less grip than it should for gentle sweepers, when threshold braking, and also during initial turn in at the end of high speed straightaways on road tracks the rear probably wants to slide out. If an effective cowl seal can be used I'd bet the bias valve for the rear brakes could be adjusted to add more bite on the rear calipers and there would be better overall braking with less dive. This would shorten braking distances and make initial turn in on high speed corners at the end of straights smoother (including auto X). Smooth = fast.

John, thanks for the feedback on the aero suggestions/education using our car. We used the "theory" of getting heat out of the engine bay which is counter-intuitive (aka. counter-productive) to your explanation for increasing grip. HA! No splash guards, shaker seal, cowl seal, etc. was a concept to get heat out. Boy, did we miss the mark when considering aero for the car. Yes, the splitter really enhances the car's front end however I had n idea what the counter effect was to the rear.

Speaking of the rear, the car has always had a loose feel in the rear. In fact, I am not comfortable at all with the rear of the car at speeds over 90mph. We have no problem getting the car to those speeds quickly, but boy is the feel uncomfortable. Granted we had issues with the 4 link and frame rails and replaced the set up with complete frame rails and the 3 link/Watts link which greatly enhanced rigidity, lateral grip and forward bite BUT the car just simply feels "wobbly", loose, wallowing (insert any and all words here) in the rear at speed. We have considered a rear diffuser or wicker bill on the rear spoiler to increase downforce but after re-reading your thread, I'm wondering if we have a lot more going on than just a rear aero issue. You demonstrate issues within the engine bay and on the front of the car, yet there is more for sure.

One place we get a tremendous amount of air is through the trans tunnel, up the shifter boot and up into the cabin of the car. Makes me wonder if I have way more issues of air flow under the car than I've ever considered...which has been very little consideration until reading your thread. Would be very curious if you have any thoughts on this concern/issue.

Thanks again for the insight and education. I have way more to learn.       
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on October 05, 2015, 10:46:44 PM
John, thanks for the feedback on the aero suggestions/education using our car. We used the "theory" of getting heat out of the engine bay which is counter-intuitive (aka. counter-productive) to your explanation for increasing grip. HA! No splash guards, shaker seal, cowl seal, etc. was a concept to get heat out. Boy, did we miss the mark when considering aero for the car. Yes, the splitter really enhances the car's front end however I had n idea what the counter effect was to the rear.

Speaking of the rear, the car has always had a loose feel in the rear. In fact, I am not comfortable at all with the rear of the car at speeds over 90mph. We have no problem getting the car to those speeds quickly, but boy is the feel uncomfortable. Granted we had issues with the 4 link and frame rails and replaced the set up with complete frame rails and the 3 link/Watts link which greatly enhanced rigidity, lateral grip and forward bite BUT the car just simply feels "wobbly", loose, wallowing (insert any and all words here) in the rear at speed. We have considered a rear diffuser or wicker bill on the rear spoiler to increase downforce but after re-reading your thread, I'm wondering if we have a lot more going on than just a rear aero issue. You demonstrate issues within the engine bay and on the front of the car, yet there is more for sure.

One place we get a tremendous amount of air is through the trans tunnel, up the shifter boot and up into the cabin of the car. Makes me wonder if I have way more issues of air flow under the car than I've ever considered...which has been very little consideration until reading your thread. Would be very curious if you have any thoughts on this concern/issue.

Thanks again for the insight and education. I have way more to learn.     

Yes, you probably do have more aerodynamic issues than you thought. That's why I PMed you and asked if it would be OK to use your car as an example.  It's an awesome car but just seeing pics on the various forums, USCA commercials etc. I figured it had aero issues from the time it was built.

There's a lot going on because of the many modifications and changes from stock. The way the car is set up is making it very hard for the radiator to cool the car as well as reducing high speed handling capabilities and pumping hot air into the cabin. I've got questions about certain things and would like to see pictures of a bunch of things but first lets address some of the things I've seen that are increasing the air pressure under hood.. Along with a reduction in front tire grip, I believe the under hood air pressure issues are at least partially contributing to the loss of rear grip and the trans tunnel heat. Adding a few things along with ride height adjustment should have a VERY dramatic affect.

Although we're discussing Amy's car I'm going to ramble about each topic as it relates to all the 2nd gens and include things I'm doing on my car.


1. The car needs a hood/cowl seal.  The hood doesn't have the grills cut out so the highest pressure  air at the base of the windshield is pushing the air to flow under the hood because it's easier than going up over or off to the sides of the windshield. The pinch welded "lip" at the leading edge of the cowl was rounded off when the firewall was smoothed so there's even less restriction "turbulence" as the air enters the engine compartment and there's a nice unrestricted path for a huge volume of air to enter. This large volume of high pressure air is raising the air pressure in the engine compartment. I don't know if the underside of the carbon fiber hood is contoured the same as a stock one so you may or may not be able to use a stock cowl gasket.

For those following along, the grills on the 70-76 stock hoods allow the pressure above and below the hood to become more equalized. When there is a stock cowl seal in place the air forced under the rear of the hood at the base of the windshield can exit up through the grills minimizing the pressure difference above and below the hood in the area above the cowl sealed off from the engine compartment. This keeps the hood from trying to lift up. This becomes more of a problem on the 77 and up cars without the grills in the hood because at high speeds the pressure under the hood above the cowl can become greater than the pressure above the hood in that area. This lifts the hood and burbs air into the engine compartment. Sometimes it's referred to as cowl shake but it's really the hood bumping up and down rapidly.

For a cheap way to test whether there's an issue with high pressure air getting into the engine bay of 2nd gen birds with hoods that do not have the grills some pipe insulation foam can be stuck in along the rear edge of the hood as seen below.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/003_zpsdhhacaru.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/003_zpsdhhacaru.jpg.html)

2. The inner wheel wells should have splash guards. Otherwise there's a big opening above the frame height the high pressure air in the wheel wells can come through into the engine bay. Increasing lift, reducing radiator cooling blah blah blah.

Shown in the top pic below is a stock "splash shield" except the small separate piece missing on the right. The lower pics are the new seals I'm making for my car out of 1/8" EPDM sheet rubber. They should seal off better than the stockers did.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/010_zpsvv9h3ux2.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/010_zpsvv9h3ux2.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/015_zpsk5xdftlk.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/015_zpsk5xdftlk.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/016_zpszu3fo1iv.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/016_zpszu3fo1iv.jpg.html)

3. I have a suspicion that the inner fender extensions might be missing on Amy's car. They seal off the front of the inner fender to the bottom of the core support keeping air from coming in from the wheel well. Without them the air moves as shown in the pic below.Again increasing lift, reducing cooling blah blah blah. I've shown my old stock one in the bottom pic, I'll be making new ones for my car but they can be bought from resto parts companies.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/004_zps6egmryro.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/004_zps6egmryro.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/007_zpsct2kaqvr.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/007_zpsct2kaqvr.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/005_zpscpb3pcyk.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/005_zpscpb3pcyk.jpg.html)
.

4. The rear of Amy's car is too low IMO. It's making it harder for the air to move smoothly and quickly under the car. So there's a pressure build up under the passenger compartment. High pressure air is trying to roll under the car along the rockers while the air that comes under the splitter, through the radiator, and all the extra air allowed because the seals are missing from the engine compartment is trying to flow under the car. The air under the car is slowed by the constriction of the narrowest point which appears to be just forward of the rear wheels. This is causing the high pressure air to try and come up through the trans tunnel while lifting the car reducing rear grip. I'd suggest raising the rear of the car a couple inches and testing. By adding "rake" to the car there's a larger area for the air under the car to flow into which I believe will make the car more stable and provide better grip for turns at speed. A rear diffuser would probably not do anything to help without raising the rear of the car first and even then a diffuser has some design requirements to actually function.  A lot of "diffusers" don't really do crap, but they look cool.

In the bottom pic we can see the height difference between the bottom of the splitter and the rear of the rocker panel. There's simply a much larger volume of air getting under the front of the car than can move through the most constricted area at the same speed. While the air speed increases right at the point of constriction lowering pressure at that point it's slowing down the air trying to enter that area increasing pressure forward of the constriction.

(http://i240.photobucket.com/albums/ff292/NOTATA/image.jpg5_zpsnuvm6onz%20-%20Copy_zpswhgyt6zo.jpg) (http://s240.photobucket.com/user/NOTATA/media/image.jpg5_zpsnuvm6onz%20-%20Copy_zpswhgyt6zo.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/KLRBRD%20on%20the%20Autocross%20at%20TMS_zps7nfjwes6%20-%20Copy_zpsg0wm5sm5.jpg) (http://s240.photobucket.com/user/NOTATA/media/KLRBRD%20on%20the%20Autocross%20at%20TMS_zps7nfjwes6%20-%20Copy_zpsg0wm5sm5.jpg.html)

If you can Jay, take a whole bunch of pictures under the car, in the engine compartment by the radiator and fans, core support, the close out panel etc and just let me know when you've put them in your photobucket account and I'll look at them.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on October 06, 2015, 09:29:33 AM
In an effort to utilize the high pressure area at the base of the windshield/cowl area on my car (with no heat/AC) I modified a stock plastic cowl grill with 3/32 EPDM sheet rubber to seal off the cowl openings. This will increase the air pressure above the cowl (downforce)and reduce the amount of air that has to find a way out under the car through the cowl drains etc. The kick panel openings are sealed off inside the car. As with some of the other seals I'm installing as the pressure increases the seal gets tighter as it's forced against the paint.

I do not think this would be a good modification for aftermarket 70-76 hoods without the grills or the 77 & up hoods without the grills because it would only increase the difference in air pressure above and below the hood rear of the cowl seal making it more likely that the hood would be pushed up unless hood pins or some other means is used to keep the rear of the hood from rising.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/015_zpsdymqh7os.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/015_zpsdymqh7os.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/011_zpsebvhimkx.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/011_zpsebvhimkx.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: pancho400cid on October 06, 2015, 11:09:36 AM
Wow... I feel like a chicken watching a card trick.....

OTOH - Really enjoying tagging along for the ride.  Very nice workmanship and I admire the thoughtful design work.  Can't wait to see how it all comes together and works.

Bound to be some dialing in I guess?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on October 07, 2015, 10:27:16 AM
Wow... I feel like a chicken watching a card trick.....

OTOH - Really enjoying tagging along for the ride.  Very nice workmanship and I admire the thoughtful design work.  Can't wait to see how it all comes together and works.

Bound to be some dialing in I guess?

Oh ya, there'll be some dialing in for sure! Most importantly the driver needs seat time!

I'm trying a couple different length splitters. I believe the long one (which would provide a lot more downforce) will need to be balanced with an adjustable rear wing. I've planned ahead for mounting a wing while doing bodywork so hopefully it won't look too much like an afterthought. Initially I'll test the shorter version splitter on the street/highways and may shorten or lengthen it , hopefully balanced by the additional downforce created by the taller rear spoiler, smooth bottom, rear diffuser, etc. before attempting the big splitter. Getting the aero right to have the car feel neutral will take some playing around I'm sure and may also include changes in spring rates, alignment settings, shocks etc.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on October 07, 2015, 11:58:29 AM
Getting back to Amy's car, which is used mostly for street and Auto-X. Lets talk about how changes in aero can affect front wheel braking. (will talk about overall braking later on)

The front end of the car is substantially lighter than a stock 73 TA I'm sure. The car has a carbon fiber hood, fenders, inner fenders, shaker scoop, and also has electric fans, aluminum radiator, aluminum fender braces, aluminum hood hinges, plus an aluminum engine!  There's probably other things that have reduced weight  I'm unaware of also. The combined weight reduction in the front is probably 200 lbs or more plus there are other things to be considered like the trunk mounted battery which is cantilevered weight on a stock TA. These reductions lower the available grip of the front tires because there's less weight pushing the tire into the pavement.

Removing weight allows the car to accelerate quicker and stop quicker (assuming no loss of traction) due to the reduction in the mass.  On the klrbird I believe all of the factors combined have removed over 150 lbs of pressure at the contact point where each of the front tires meet the pavement. This lowers the available braking grip before the tire looses traction and skids (will talk about "turn in" grip later on).

Auto -X is a time vs. distance competition. So if we can keep the car at a higher speed during a greater percentage of the distance traveled the overall time to complete the course would be lower. Assuming the corners are taken at the maximum speed already, the longer the distance the car is at it's highest speed at the end of the straight (or somewhat straight) sections would reduce the time on course. This is where the added braking grip using aero techniques comes into play.

The hood of a 2nd get bird has over 3000 Sq In of surface area. If the difference in air pressure above/below the hood is changed just 0.1 lb. per Sq. In. it will add or reduce pressure at the contact patch of the front tires 300+ lbs (150 per wheel). If we can add 300 lbs of grip to the contact patches without having to battle the momentum of 300 lbs of actual weight the car will be able to slow quicker because we can brake harder before skidding occurs. Particularly at the beginning of braking action when traveling high speeds when air pressure differences above/below the hood are greater. On an Auto-X this will allow the braking to be delayed just a little bit for corners at the end of each straight (or somewhat) section.

At Auto X speeds this might mean the car could go let's say 5' longer at the highest speeds (at the end of straights) on the course before braking. So the car will travel that 5' more quickly. When we add up 2'-5'-10' here and there throughout the course the linear feet traveled at the highest speeds will accumulate lowering the overall elapsed time.

Changing the air pressure under/over hood in a way that reduces lift/increases down force will also reduce time in the speed/stop challenges because of the additional grip available at the beginning of threshold braking.

The additional grip added by a pressure difference on the hood at highway speeds might be just enough extra grip before the tires skid to reduce the stopping distance at highway speeds enough to avoid hitting an animal or other unusual object.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: mrbandit on October 08, 2015, 06:40:17 AM
John, I saw this article and you immediately came to mind.  There is so much stuff going on that I know you would appreciate if you haven't seen it already.

http://www.msn.com/en-us/autos/enthusiasts/the-callaway-corvette-c7-gt3-r-is-darth-vaders-racer/ar-AAfcwhZ (http://www.msn.com/en-us/autos/enthusiasts/the-callaway-corvette-c7-gt3-r-is-darth-vaders-racer/ar-AAfcwhZ)

(http://img-s-msn-com.akamaized.net/tenant/amp/entityid/AAfcgKD.img?h=364&w=728&m=6&q=60&o=f&l=f&x=1099&y=730)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: skisix38off on October 08, 2015, 06:58:19 AM


The hood of a 2nd get bird has over 3000 Sq In of surface area. If the difference in air pressure above/below the hood is changed just 0.1 lb. per Sq. In. it will add or reduce pressure at the contact patch of the front tires 300+ lbs (150 per wheel). If we can add 300 lbs of grip to the contact patches without having to battle the momentum of 300 lbs of actual weight the car will be able to slow quicker because we can brake harder before skidding occurs. Particularly at the beginning of braking action when traveling high speeds when air pressure differences above/below the hood are greater. On an Auto-X this will allow the braking to be delayed just a little bit for corners at the end of each straight (or somewhat) section.


John,

I agree with what you have to say above but this part intrigues me.  Your statement is correct above a .1PSI difference spread over 3000 in^2 could start to add up.  My opinion is that aero is not really that effective at autocross speeds.  A very open and fast autocross course for me will see speeds of 75-80mph and only very briefly at that.  A more typical max autocross speed would be closer to 60mph.  I read somewhere that the rear spoiler on TA's provides a 100# down force at 100mph and this equation isn't linear so, at 60mph I may have 40# of down force from that spoiler.

How do you envision creating that kind of difference?  This would help me as well.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on October 08, 2015, 10:31:24 AM


The hood of a 2nd get bird has over 3000 Sq In of surface area. If the difference in air pressure above/below the hood is changed just 0.1 lb. per Sq. In. it will add or reduce pressure at the contact patch of the front tires 300+ lbs (150 per wheel). If we can add 300 lbs of grip to the contact patches without having to battle the momentum of 300 lbs of actual weight the car will be able to slow quicker because we can brake harder before skidding occurs. Particularly at the beginning of braking action when traveling high speeds when air pressure differences above/below the hood are greater. On an Auto-X this will allow the braking to be delayed just a little bit for corners at the end of each straight (or somewhat) section.


John,

I agree with what you have to say above but this part intrigues me.  Your statement is correct above a .1PSI difference spread over 3000 in^2 could start to add up.  My opinion is that aero is not really that effective at autocross speeds.  A very open and fast autocross course for me will see speeds of 75-80mph and only very briefly at that.  A more typical max autocross speed would be closer to 60mph.  I read somewhere that the rear spoiler on TA's provides a 100# down force at 100mph and this equation isn't linear so, at 60mph I may have 40# of down force from that spoiler.

How do you envision creating that kind of difference?  This would help me as well.

I agree that aero considerations (all else being equal) won't make much of a difference for probably 90% or more of a typical Auto X course (with these type cars). The greatest possibility of aero mods reducing the overall elapsed time (for these type cars) is primarily in the braking zone of the straight sections. If the car is travelling 60 MPH and you can hold off braking for say 5' longer on 5 straights the car has traveled 25' at 60 MPH. If the car had started braking 5' earlier it might have dropped speed to somewhere in the low 50's during that 5' so it takes longer to cover the 25'. I don't have the math background to do the equation or the info on how much a car slows during the 5' to determine how much time is involved.

You are correct in that the rear spoiler looses effectiveness as speed drops. This is why you'll see folks with really tall rear spoiler extensions at some Auto_X venues. The additional increase in air pressure on the deck lid is disproportionate to the increase in height in that a 10% height difference will give you more than a 10% increase in pressure (to a point). The increased drag of the real tall spoilers is offset by the additional grip available for braking as well as possibly increasing available grip during cornering sections like slaloms. Most of the PT cars have enough power to overcome the additional drag of the tall spoiler at Auto_X speeds. The increased rear grip of the real tall rear spoilers can allow a brake bias change that might further reduce overall braking distance and the time period braking is required to drop a certain amount of speed. Will talk more about this later on..

Amy's car: The lift which is causing the scary instability at 90+ is still there but reduced at Auto_X speeds. It's likely requiring her to brake earlier (to avoid skidding) than would be necessary if the tires had more grip. The tires are very wide 18's with a huge contact patch and are probably the lowest tread wear, stickiest, tires that are legal at the GG, USCA, and other PT type events. They probably aren't being used to anywhere close to their full potential. The changes I recommended to reduce lift/increase down force should increase grip and still be well below the tires full capabilities since the car would really only be returning to essentially stock. The changes to her car are more to "fix" things that have reduced the cars capabilities rather than reduce lift, increase down force, or reduce drag (compared with stock) like the things I'm changing on my own car.

My 70 clone and Amy's 73 TA are essentially the same exterior. I have an old Hotchkis set up for springs, sways, etc. with basic Bilsteins and the car is a couple inches lower than stock. I ran my car with no aero mods at road tracks and Land speed racing events many times at speeds up to the drive line limited top speeds of around 150 MPH and the car is very stable. Driving at 130 on track seems like 70 on the highway. Windows are up for LSR and after 130 one of my windows would suck out a little because I was missing one of the "blow out" clips and wind noise would increase. At road tracks windows are down so high speeds seem the same, just more wind noise as speed increases.

I don't know if there's any aero differences due to the difference of the suspension, exhause etc. under Amy's car Vs. my car because I haven't seen many pics underneath other than the recent rear suspension change.  Her car is a bit lower than mine but I don't think that would have an adverse effect other than the rake change I recommended trying. So if the car is brought back more to stock with seals etc. I'd think they could blast up to 125+ without stability issues. And, much quicker than I can! ahahaha
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on October 09, 2015, 10:56:02 AM
John, I saw this article and you immediately came to mind.  There is so much stuff going on that I know you would appreciate if you haven't seen it already.

http://www.msn.com/en-us/autos/enthusiasts/the-callaway-corvette-c7-gt3-r-is-darth-vaders-racer/ar-AAfcwhZ (http://www.msn.com/en-us/autos/enthusiasts/the-callaway-corvette-c7-gt3-r-is-darth-vaders-racer/ar-AAfcwhZ)

(http://img-s-msn-com.akamaized.net/tenant/amp/entityid/AAfcgKD.img?h=364&w=728&m=6&q=60&o=f&l=f&x=1099&y=730)

Callaways media people did a very good job of getting the press release to pop up everywhere at almost the same time. I saw it on Race Car Engineering. It'll be interesting to see how well it does racing and if they make changes after real world use.  http://www.racecar-engineering.com/news/corvette-c7-gt3-revealed/?utm_source=The%20Chelsea%20Magazine%20Company%20Ltd&utm_medium=email&utm_campaign=6254402_RCE%20Editorial%20Oct%202015&dm_i=6NM,3Q1XE,KNBIE6,DEFEV,1
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1973klrbrd on October 09, 2015, 07:43:34 PM
John, I have been off the grid a bit with business travel so I have some serious catching up to do with the posts. There is a lot to process what you are observing and suggesting for Amy's car. I'm taking the car out of storage this weekend for a show and long drive so I will attempt to get some pics. 
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on October 12, 2015, 09:55:32 AM
Finished up mounting the inner fender seals and made some new inner fender extensions. Will put the seals on using threaded hardware after final paint so I can easily change the seals to conform to tubular control arms whenever I get them.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/006_zpsgyzwmeqk.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/006_zpsgyzwmeqk.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/002_zpszbemqha6.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/002_zpszbemqha6.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: jonathonar89 on October 18, 2015, 04:37:43 PM
Great work Johnny...truely amazing to take your ideas and put it to work.  I would like to do some similar but different things with my '79.

Jon
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on October 19, 2015, 09:30:52 PM
Great work Johnny...truely amazing to take your ideas and put it to work.  I would like to do some similar but different things with my '79.

Jon

Thanks!

What are you considering for your car? Please share it here. I want this thread to be about the whole 2nd gen not just early cars or my car. The advancements in mechanical grip and tires have been huge the past 10-15 years. Aero is the next step.

The late cars with the pointed front split the air lower at the front which changes the air flow and probably reduces drag with better attached flow over front section of the hood. I'd like to do a tuft test on both styles to see the difference at highway speedsusing a camera mounted on the hood.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: jonathonar89 on October 20, 2015, 06:17:50 AM
Great work Johnny...truely amazing to take your ideas and put it to work.  I would like to do some similar but different things with my '79.

Jon

Thanks!

What are you considering for your car? Please share it here. I want this thread to be about the whole 2nd gen not just early cars or my car. The advancements in mechanical grip and tires have been huge the past 10-15 years. Aero is the next step.

The late cars with the pointed front split the air lower at the front which changes the air flow and probably reduces drag with better attached flow over front section of the hood. I'd like to do a tuft test on both styles to see the difference at highway speedsusing a camera mounted on the hood.


I was thinking rear adjustable spoiler mounted under the gas tank/bumper area would be great on these cars.  If someone was to really get serious, they could make it work off the brake system as an aid.  McLaren supercars also have self-adjusting spoiler based on brake input.  Another thing to note is that when drag race cars start getting loose at high speed, the drivers throw the parachute to straighten the car out. 

One thing I notice on the 79-81 rear bumper is that it's an identical match for the grill section in the front but not cut out.  In the future I would like to try and cut the rear bumper cover, insert the covers and the build an exhaust exit or use the low pressure area for something.

On my car I switched to a VFN cowl hood.  I liked my Trans Am shaker scoop but the open back would pull in rain when I was daily driving and I didn't care for that too much.  The main issue I will have now is that the cowl hood does block vision.  This may be an issue for track visibility like you were having with the shaker. 

I know you're trying to keep the factory look.  I am too but my car will be more about how I think they should've been built from a styling point....function will follow.  This is why I think foilers are great.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: OLDFLM on October 20, 2015, 01:00:53 PM
Dammit John!  All the efforts to "smooth" the look of my car... eliminating the cowl vents... smoothing the 71 only functional fender vents... functional Formula hood without the functional air cleaner...  you're killin' me with all these lessons on aerodynamics!  But I'm really enjoying the thread!!
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on October 20, 2015, 08:23:11 PM
I was thinking rear adjustable spoiler mounted under the gas tank/bumper area would be great on these cars.  If someone was to really get serious, they could make it work off the brake system as an aid.  McLaren supercars also have self-adjusting spoiler based on brake input.  Another thing to note is that when drag race cars start getting loose at high speed, the drivers throw the parachute to straighten the car out. 

One thing I notice on the 79-81 rear bumper is that it's an identical match for the grill section in the front but not cut out.  In the future I would like to try and cut the rear bumper cover, insert the covers and the build an exhaust exit or use the low pressure area for something.

On my car I switched to a VFN cowl hood.  I liked my Trans Am shaker scoop but the open back would pull in rain when I was daily driving and I didn't care for that too much.  The main issue I will have now is that the cowl hood does block vision.  This may be an issue for track visibility like you were having with the shaker. 

I know you're trying to keep the factory look.  I am too but my car will be more about how I think they should've been built from a styling point....function will follow.  This is why I think foilers are great.

A spoiler that extends downward under the car? A couple 12 V linear actuators could probably be used to move the spoiler.

I am trying somewhat to keep the factory appearance on this car. Probably a good thing since if I got really carried away I'd probably be to old and frail to drive the darn thing once done.  Is your cowl hood sealed to the cowl? Are you running a carb pan sealed to the hood?

I'm going to have to examine the rear bumper area on the 79's to see what you're considering for the exhaust or something. Might work well as the top section of a double diffuser.

(http://i240.photobucket.com/albums/ff292/NOTATA/diffusor_outlet_zps81d03fc0.png) (http://s240.photobucket.com/user/NOTATA/media/diffusor_outlet_zps81d03fc0.png.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on October 20, 2015, 08:51:36 PM
Dammit John!  All the efforts to "smooth" the look of my car... eliminating the cowl vents... smoothing the 71 only functional fender vents... functional Formula hood without the functional air cleaner...  you're killin' me with all these lessons on aerodynamics!  But I'm really enjoying the thread!!

TY!  Good to see ya pop in here! You been lurking? Remember what I said about that center hood latch 6-7 years ago and how adamant I was about using it? Now you know why.

Many of you following this thread probably don't know Ty or his car "Freedom Bird" since he averaging less than a post per year. However he's been a hardcore Firebird guy a long time. His car was documented in one of those epic build threads and then it went to the big SEMA show, PRI, TV shows etc.   I built a carbon fiber dash for it then went to the shop it was at up in GA and spent a week helping assemble it for the SEMA show back in 09. Here's the car.

(http://i240.photobucket.com/albums/ff292/NOTATA/0114.jpg) (http://s240.photobucket.com/user/NOTATA/media/0114.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: jonathonar89 on October 20, 2015, 10:53:00 PM
I was thinking rear adjustable spoiler mounted under the gas tank/bumper area would be great on these cars.  If someone was to really get serious, they could make it work off the brake system as an aid.  McLaren supercars also have self-adjusting spoiler based on brake input.  Another thing to note is that when drag race cars start getting loose at high speed, the drivers throw the parachute to straighten the car out. 

One thing I notice on the 79-81 rear bumper is that it's an identical match for the grill section in the front but not cut out.  In the future I would like to try and cut the rear bumper cover, insert the covers and the build an exhaust exit or use the low pressure area for something.

On my car I switched to a VFN cowl hood.  I liked my Trans Am shaker scoop but the open back would pull in rain when I was daily driving and I didn't care for that too much.  The main issue I will have now is that the cowl hood does block vision.  This may be an issue for track visibility like you were having with the shaker. 

I know you're trying to keep the factory look.  I am too but my car will be more about how I think they should've been built from a styling point....function will follow.  This is why I think foilers are great.

A spoiler that extends downward under the car? A couple 12 V linear actuators could probably be used to move the spoiler.

I am trying somewhat to keep the factory appearance on this car. Probably a good thing since if I got really carried away I'd probably be to old and frail to drive the darn thing once done.  Is your cowl hood sealed to the cowl? Are you running a carb pan sealed to the hood?

I'm going to have to examine the rear bumper area on the 79's to see what you're considering for the exhaust or something. Might work well as the top section of a double diffuser.

(http://i240.photobucket.com/albums/ff292/NOTATA/diffusor_outlet_zps81d03fc0.png) (http://s240.photobucket.com/user/NOTATA/media/diffusor_outlet_zps81d03fc0.png.html)

No cowl section seal or box setup for the air cleaner on mine yet.  Right now I'm working on an efi conversion that also turned into a rear end rebuild and suspension out back.  It's been getting expensive for my budget to say the least but I'm making moves.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: mrbandit on October 21, 2015, 06:51:33 AM
The freedom bird was an awesome build.  A lot of a good products came to life during that build. 
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: OLDFLM on October 21, 2015, 07:21:58 AM
Thanks Bandit!  Yes, there are a lot of prototype parts on my car that enabled the manufacturers to get new products to market... AutoRad, Marquez Design, Anvil, Fesler, ACC, American Autowire, BMR...  especially for the 70-73s where there just wasn't much available at the time.  It was a fun experience... wasn't it John!   :roll: 

Yes, I'm a lurker.  I don't post much on the boards I frequent as I don't want to come across the wrong way... my car and I have already had our "15 minutes" and I just want to enjoy the hobby and my car, and learn what I can from great threads like this one! 

With that said, John, if you need any pics or need another guinea pig just lmk my friend!
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on December 04, 2015, 04:12:17 PM
I'm going to watch this thread with great interest. I already have the splitter on my car and now looking at other aerodynamic changes, for pretty much the same reason. This thread is good reading so far. Has anyone taken a look at Ron Sutton's threads?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on December 04, 2015, 06:27:29 PM
I'm going to watch this thread with great interest. I already have the splitter on my car and now looking at other aerodynamic changes, for pretty much the same reason. This thread is good reading so far. Has anyone taken a look at Ron Sutton's threads?

I participated in Ron's aero thread over on PT but once his business started to take off and he started his seminar tour and book promotions he pretty much stopped replying to his technical threads.

I'm guilty of not keeping this thread alive myself the past month or so. Been spending a lot of my time studying under body aerodynamic designs of road cars like the McLaren F-1, P1 Ferraris, and race cars like the Group C cars of the late 80's early 90's as well as IMSA, DTM, F1,  etc. while working on designs for the bottom of my car.

Do you have any good pics of your splitter set up you can share? There's a lot more folks with the later 2nd gen cars and I'm sure they'd be interested to see what you've done and hear how it's worked for you.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on December 04, 2015, 11:37:08 PM
Hopefully these pics will work. Keep in mind this splitter was the result of a compromise. I'd been following Ron's aero threads and believed the splitter needed to reach out at least as far forward as the leading edge of the bumper to be most effective. A friend (who also drives the car on track days and has a decade + of experience) disagreed, and preferred the shorter reach. Same guy also argues for a more distinct rake (higher rear suspension) to INCREASE the rear to front weight transfer under heavy braking. Doesn't matter how many modern cars I point out that have relatively flat suspensions.

*sigh* Ever argue with a stubborn lawyer? Not worth the heartburn to prove one way or the other, so I let it rest.

The raw material (plywood) didn't cost that much anyway, and I can always make another splitter. For what it's worth, there are three grades of pine-based 1/2" plywood at Menards. The most expensive has 7 layers and is noticeably more rigid and lighter than the other two. It cost me $30 bucks for a 4x8' sheet. The mounting hardware came from Tractor Supply. It was another $15. My front bumper cover is fiberglass and it's lower edge is mounted to an aluminum front bumper made from a 2x2x1/4" L-shaped extrusion. The upper ends of the turnbuckles are mounted to the same bumper.

Feel welcome to critique and offer suggestions for improvement.

(http://www.silverblade.net/images/car/splitter1.jpg)

(http://www.silverblade.net/images/car/splitter2.jpg)

(http://www.silverblade.net/images/car/splitter3.jpg)

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on December 06, 2015, 10:28:35 AM
I have argued with lawyers! ahahaha

Everything we do to these cars is a compromise of some sort. however, even if we were designing a completely new car we'd still have to make compromises. Now that your bud has tried his way I'd suggest making a longer splitter that extends to the leading edge of the bumper like you wanted and test.

I'll make a couple drawings about the later noses and comment on the rake and splitter length when I've got more time in the next day or two to write a longer post.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on December 10, 2015, 02:22:36 PM
just did a complete read of the thread and came away some ideas to help my car out. For starters, I will be blocking off the open area under the bumper cover and above the front air dam. Big gaping hole there, allowing pressurized air in, exaggerated by the presence of the splitter. Next thing will be rubber sheets to fill in the wheel opening around the upper control arms. My car didn't have those when I got it, and it didn't occur to me they actually had a function beyond keeping splashed water out.

One thing I do have to offset the enormous underhood pressure is the seal and most of the rim for my shaker has been trimmed away. This was to make the original LS1 fit with a carb, but with the LS3 and EFI, I now have an adjustable air gap on the leading edge. I can go from roughly 2" of space, to "closed" if I set up the right adjustable rig.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on December 11, 2015, 11:11:48 AM
just did a complete read of the thread and came away some ideas to help my car out. For starters, I will be blocking off the open area under the bumper cover and above the front air dam. Big gaping hole there, allowing pressurized air in, exaggerated by the presence of the splitter. Next thing will be rubber sheets to fill in the wheel opening around the upper control arms. My car didn't have those when I got it, and it didn't occur to me they actually had a function beyond keeping splashed water out.

One thing I do have to offset the enormous underhood pressure is the seal and most of the rim for my shaker has been trimmed away. This was to make the original LS1 fit with a carb, but with the LS3 and EFI, I now have an adjustable air gap on the leading edge. I can go from roughly 2" of space, to "closed" if I set up the right adjustable rig.

The late 2nd gens were designed as bottom feeders.The opening under the extended nose section feeds the radiator using the high pressure air under the extended nose in front of the air dam. Unless you make an extended air dam that starts at the leading edge of the bumper you might be better off blocking the openings in the front of the bumper and the grills for smoother airflow. I would test it both ways but I have a feeling you'll find that blocking the lower opening may cause overheating issues under certain conditions unless the regular grills are removed or something else is done to increase the available flow to the radiator.

Your adjustable opening probably won't help reduce underhood pressure due to the increased pressure in front of the shaker (unless underhood pressure is high). In fact air may go in rather than out. I'd like to see some tuft testing on that at highway speeds. I've been going to delve into the subject of the shakers in this thread discussing under/over hood pressures, but haven't gotten into it yet.

I did draw up a few sketches using the later 2nd gen nose style concerning what I think are likely 2 dimensional flow patterns. Keep in mind that the addition of splitters and air dams will also cause more air to flow to the sides of the car as well.

A.  The stock vehicle. I set the stagnation point at the mid point of the leading edge of the bumper although I believe it's likely to actually be even a little higher. A lot of air passes below the bumper creating a high pressure area (used for radiator cooling) and causing lift. Because this area is in ground effect simply putting lowering springs on the car will reduce the flow under the car helping to reduce lift and as an added bonus lowers the center of gravity.

B. The short splitter on stock air dam (1981roadrace current). I believe this will lower the stagnation point a little as shown due to lowering the bottom surface the 1/2" thickness of the splitter thus increasing the depth of the air dam function by 1/2" combined with the increased resistance to flow under the car by having the splitter extended forward of the air dam. So more air goes over car and more air is directed to the sides of the car reducing the volume of air passing under the car. This should reduce lift to some degree and slightly reduce turbulence (drag) under the car, particularly directly under the splitter. Because the splitter is still under the nose of the car I doubt there would be much of a lift reduction or any increase in down force from the high pressure above the splitter as that pressure is also acting to push up under the nose cancelling the effect to a degree. Potentially a high pressure area is formed above the splitter where it extends past the wheel flares into the wheel well which is caused by the rotation of the tires.

C. Extended splitter to beyond leading edge of bumper and attached to bottom of stock air dam. Significantly lower stagnation point is just above splitter causing a lot more air to go over the car which would greatly reduce lift. The high pressure area on top of the splitter is still there however there is a high pressure area forward of the bumper where there is pressure pushing down. There is a further reduction in the volume of air going under the splitter reducing lift because the air can speed through instead of slowing down.

D. Extended depth air dam from leading edge of bumper with extended splitter. By increasing the depth of the air dam a lot more air is prevented from going under the car. Downforce is created on the top of the exposed area above the splitter forward of the air dam. With the dam brought forward to the leading edge of the bumper flow over the car is smoothed and low pressure is created under the splitter area. The bottom feed of the radiator would be closed off so the grills or other openings in the bumper might have to be modified.

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/CCF12112015_0002_zpshzzoybhf.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/CCF12112015_0002_zpshzzoybhf.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/CCF12112015_0003_zpsdwhy3j3l.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/CCF12112015_0003_zpsdwhy3j3l.jpg.html)

Your buddy who recommended increasing the rake of the car might be on to something. Does the car sit level or has some rake?

When these cars were new they had a nose up attitude. Something about the marketing guys thinking the cars should look like they were taking off while sitting still or something like that. In any case, the stock nose up attitude makes the front end lift at high speeds. Level is better, and a rake (not 70's air shock style) with the rear up a bit makes the car more stable (moves center of pressure toward rear) and reduces lift at higher speeds thereby increasing the "weight" on the tires which allows more braking before skidding. Raising the rear of the car only changes the static front/rear weight distribution a very small amount and wiould have very little effect on braking at low speeds however as speed increases the rake can have a noticeable effect on many cars.

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/Aerodynamics_DownforceFromRakedUnderbody_zpsoemsjrdv.png) (http://s240.photobucket.com/user/NOTATA/media/AERO/Aerodynamics_DownforceFromRakedUnderbody_zpsoemsjrdv.png.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on December 11, 2015, 01:17:14 PM
The late 2nd gens were designed as bottom feeders.

So why do late 4th gen Camaros look like catfish then?  :-P

Very informative and helpful, I can't thank you enough for illustrating this. The car does have a slight rake, with the rear suspension on Hypercoil composite leafs with a 4.5" arch. It appears to be close to stock ride height. The front suspension is on adjustable coilovers:

(http://silverblade.silverpen.org/images/car/autocross.jpeg)

Does the idea of relieving underhood pressure via venting at the leading edge of the shaker have any merit?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on December 11, 2015, 07:09:15 PM

So why do late 4th gen Camaros look like catfish then?  :-P

Pontiac had already hired all the good stylists? ahahaha .... They're bottom feeders so the grill is for looks? Some of the guys who race them change them to front breathers to get more down force on splitters. Lots of cars now only have grills for appearance. Especially since they started making the front ends blunt for hitting pedestrians. Otherwise there'd just be a big rounded nose on the cars. There are some with active louvers also to aid aero for mileage.

Does the idea of relieving underhood pressure via venting at the leading edge of the shaker have any merit?

I don't think it would improve anything much but you could tuft test on the highway.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: skisix38off on December 17, 2015, 08:10:00 AM
I'm going to watch this thread with great interest. I already have the splitter on my car and now looking at other aerodynamic changes, for pretty much the same reason. This thread is good reading so far. Has anyone taken a look at Ron Sutton's threads?

I participated in Ron's aero thread over on PT but once his business started to take off and he started his seminar tour and book promotions he pretty much stopped replying to his technical threads.



I was lucky enough to go to the Texas stop on Ron's tour and have read a lot of his threads on aero.  He has obviously been doing this for a long time and has forgotten more than most of us will learn.  I learned a lot during his seminar and have a different perspective on aero and handling than I did going into the seminar.  Ron is an all out guy though and is willing to sacrifice a lot of street car in favor of racing.  It was apparent to me during the seminar that that view point is not widely shared.  I think a lot of us have street cars that we strive to make faster but, they are street cars.  RoadRace - I get the sense you only race your TA so he's got a lot of stuff for you and you might benefit from his book.

Has anyone ever considered putting vents in their hood to allow all the air that goes through the radiator to continue leaving over the top of the car?  I'm thinking of something similar to Mike Dusold's Camaro ( Dusold Design's).
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: cal30_sniper on December 17, 2015, 09:55:25 AM
I participated in Ron's aero thread over on PT but once his business started to take off and he started his seminar tour and book promotions he pretty much stopped replying to his technical threads.

Has anyone ever considered putting vents in their hood to allow all the air that goes through the radiator to continue leaving over the top of the car?  I'm thinking of something similar to Mike Dusold's Camaro ( Dusold Design's).

The vents on that car are far enough forward that they might actually work. Anything further back, and you start getting into a higher pressure area that wouldn't be effective at relieving that pressure under the hood. Problem I see, is that between accessory belt routing and the radiator/core support, space is at a premium that far forward on the hood. The early 2nd Gen hood isn't nearly as flat as a 1st Gen or late 2nd Gen, so that would be a problem on the early cars as well.

Of course, the 3rdGen T/As used something similar to this, albeit spaced more towards the rear side of the hood, I would guess in an attempt to get them into cleaner air. Kind of a weird middle ground between the 2nd Gen fender extractors and the hood vents on that Dusold Camaro.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on December 17, 2015, 11:01:11 AM
Sniper, excellent that you got to one of Rons seminars! I'd like to attend one if he ever comes this way. We've been in touch regularly and I've purchased a bunch of stuff from his company. He did the brake calculations for my car for me recently so I'd get the pedal arm ratio, twin master piston bore sizes, etc. correct.  I'm not a math wiz.

In the pics I've seen of the Dusold Camaro there is no duct work from the radiator to the hood openings so there's certainly no way "all" the air that flows through the radiator exits through the hood. What is seen, are twin turbos directly under the openings with lots of heat wrap on the turbo tubes which were there before the hood was opened up. The hood openings may have been done in an effort to lower under hood temps, although increased grip by reducing under hood pressure may be occurring as an unintended benefit. I did see he used Gurney flaps at the leading edge of the openings to help draw air out.

The over/under hood pressure on the 2nd gens is different for most of us with modified cars because of the various front end designs and individual changes we've made to our cars. While hood vents of some type may be good on one car the same vent in the same location might be neutral or have a negative effect on another. I've been writing a post on 2nd gen bird under/over hood pressure (complicated subject) and it's relevance to hood scoops, vents, etc. and the effects of such devices on lift and drag. I will probably have a race car aerodynamicist review it before posting.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: skisix38off on December 17, 2015, 04:01:29 PM

In the pics I've seen of the Dusold Camaro there is no duct work from the radiator to the hood openings so there's certainly no way "all" the air that flows through the radiator exits through the hood. What is seen, are twin turbos directly under the openings with lots of heat wrap on the turbo tubes which were there before the hood was opened up. The hood openings may have been done in an effort to lower under hood temps, although increased grip by reducing under hood pressure may be occurring as an unintended benefit. I did see he used Gurney flaps at the leading edge of the openings to help draw air out.



From what you describe, those pictures are from Mike's car as it was last year.  The front air dam channels air through the radiator and then out through the hood vents.  I spend some time around this car.  Also, the turbo's are located right in front of the doors now. 

Now, I'm not saying we can do this- Mike's car is a tube frame car now with one piece front end.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on December 17, 2015, 05:35:17 PM

From what you describe, those pictures are from Mike's car as it was last year.  The front air dam channels air through the radiator and then out through the hood vents.  I spend some time around this car.  Also, the turbo's are located right in front of the doors now. 

Now, I'm not saying we can do this- Mike's car is a tube frame car now with one piece front end.

Ya, I'm remembering how it was before then. Is there duct work from the radiator to the vents now? Can you get pics? ask him how it's working out?

I've seen cars where the radiator is tipped and a sealed duct is between the fan and hood opening. I'd think the late 2nd gen bottom feeder cars would be the easiest to do that to. However I don't know whether or not it would have an advantage or disadvantage with cooling, under hood pressure, or drag. and that might depend on the particular car.

Here's one of the nicest looking 2nd gen hood vents I've seen. Dunno if they work or anything else about them.

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/Iw_640_zpsyxxmjmig.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/Iw_640_zpsyxxmjmig.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on January 07, 2016, 11:02:04 AM
Willem Toet is a well known F-1 race car and aerodynamics specialist. During the past few months he's been sharing some of his knowledge. Although he could write and speak in terms the average car guy would get lost trying to follow he presents information in terms the average person can understand. I recommend this piece he published yesterday on air ducts for intakes and radiator cooling, particularly for the guys with the later 2nd gens who might be blocking off the bottom feeder and adding a splitter. https://www.linkedin.com/pulse/air-ducts-down-earth-guide-motorsport-applications-willem-toet

You'll find a listing of the motorsport pieces he's written recently which include a number of aerodynamic articles here. https://www.linkedin.com/today/author/187006218
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on February 02, 2016, 10:58:47 PM
I kept tabs on the Daytona 24 hour race this past weekend because I expected it to be very good which it was. There were a lot of changes to rules affecting aerodynamics in several classes which I wanted to keep tabs on. The Corvette camp really did a great job taking 6 of the top 8 spots overall in a race that included more manufacturers than any other road race will this year. Ferrari, Porsche, Ford, Dodge, Lamborghini, Mazda, Nissan, Honda, BMW, Aston Martin, and Audi all sent their best and the GM boys took almost all the top spots.

The aero changes for the Corvettes can be seen here. http://www.hotrod.com/features/1601-body-aero-secrets-of-the-2016-corvette-racing-c7-r/

Even if you don't watch road racing normally the last 12 minutes of this years 24 hour race at Daytona race is worth watching. You wouldn't think the race would be this >< close after 24 hours!  https://www.youtube.com/watch?v=gW_wOb5Aco8
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: tazzz2 on February 04, 2016, 10:43:30 PM
John you've done a Hell of a job here, I take my hat off to you.

This subject is something I have been digging deeper and deeper into and is always evolving as it relates to our cars... The weight split on a typical 70 Firebird from the factory was 63% front 37% rear (as established by the 70 Formula Cochise prior to working on the car)... When completed that car weighed in with a split of 51% front and 49% rear. Following the above example it could be reasonably said that Amy's car is roughly neutrally balanced (more or less) and placing the TA spoilers and split on the car does create further down force. At the time of the sale we were just scratching the surface of Areo as it relates to our cars and my focus was to continue the process of building molds for the various parts on these cars. BTW we just finished the complete roof inner and outer in Carbon, shameless plug gang ;-)

The biggest thing I have personally taken from lengthy conversations with likes of Ron Sutton and others specifically in the Fluid Dynamics arena is that no one shoe fits all. Air flow will of course move over surfaces as a constant and have noted effects. This said we should learn as much as possible and be very careful not to generalize. Adding considerable weight to a car in any one area can cause you to reflect on solutions and balances possibly...

I noted the references to the hood vents and have also looked closely at them (along with discussed them extensively with others much smarter than I)... In some cases these are required for heat dissipation,  and in the case of our cars I have been advised that they can generally serve to interrupt the airflow surface tension and somewhat minimize the high pressure area at the base of the windshield.

Given my lack of education in this specific area I'm forced to read as much as possible, and learn as best as I can.  I appreciate when we all get together and discuss these influences and speak with professionals too... To that end I have reached out to a graduate from the University of Toronto that studied fluid Dynamics and he has expressed an interest in playing with a few concepts I have whipped up in my crazy own little way... One of the ideas I have is a completely redesigned rad support for our cars. You see the shape of the nose and the air flow behind the nose of an early second gen is lacking to say the least.. If one were to manage or channel or direct the air and then utilize an active shutter/louver system to control air volume under the hood, that air pressure at could be greatly mitigated at speed and otherwise opened up when appropriate. 

This would also be further enhanced by possible extending the spliter back under the car in the form of a motor forward belly pan. This extend surface experiment was done on a buddies second gen causing him to radically increase his rear spoiler height/design as the car became so nose heavy that he removed it at an event until he could address the rear of the car.

Anyways I'm babbling on here, but will come by and check back on the thread when I can from time to time.. Hopefully I can share info in the future that I've personally learned, and continue to learn here as well... Congrats to all involved in participating here and pushing the Areo improvements for these early cars....   
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 20, 2016, 09:47:18 PM
John you've done a Hell of a job here, I take my hat off to you.

This subject is something I have been digging deeper and deeper into and is always evolving as it relates to our cars... The weight split on a typical 70 Firebird from the factory was 63% front 37% rear (as established by the 70 Formula Cochise prior to working on the car)... When completed that car weighed in with a split of 51% front and 49% rear. Following the above example it could be reasonably said that Amy's car is roughly neutrally balanced (more or less) and placing the TA spoilers and split on the car does create further down force. At the time of the sale we were just scratching the surface of Areo as it relates to our cars and my focus was to continue the process of building molds for the various parts on these cars. BTW we just finished the complete roof inner and outer in Carbon, shameless plug gang ;-)

The biggest thing I have personally taken from lengthy conversations with likes of Ron Sutton and others specifically in the Fluid Dynamics arena is that no one shoe fits all. Air flow will of course move over surfaces as a constant and have noted effects. This said we should learn as much as possible and be very careful not to generalize. Adding considerable weight to a car in any one area can cause you to reflect on solutions and balances possibly...

I noted the references to the hood vents and have also looked closely at them (along with discussed them extensively with others much smarter than I)... In some cases these are required for heat dissipation,  and in the case of our cars I have been advised that they can generally serve to interrupt the airflow surface tension and somewhat minimize the high pressure area at the base of the windshield.

Given my lack of education in this specific area I'm forced to read as much as possible, and learn as best as I can.  I appreciate when we all get together and discuss these influences and speak with professionals too... To that end I have reached out to a graduate from the University of Toronto that studied fluid Dynamics and he has expressed an interest in playing with a few concepts I have whipped up in my crazy own little way... One of the ideas I have is a completely redesigned rad support for our cars. You see the shape of the nose and the air flow behind the nose of an early second gen is lacking to say the least.. If one were to manage or channel or direct the air and then utilize an active shutter/louver system to control air volume under the hood, that air pressure at could be greatly mitigated at speed and otherwise opened up when appropriate. 

This would also be further enhanced by possible extending the spliter back under the car in the form of a motor forward belly pan. This extend surface experiment was done on a buddies second gen causing him to radically increase his rear spoiler height/design as the car became so nose heavy that he removed it at an event until he could address the rear of the car.

Anyways I'm babbling on here, but will come by and check back on the thread when I can from time to time.. Hopefully I can share info in the future that I've personally learned, and continue to learn here as well... Congrats to all involved in participating here and pushing the Areo improvements for these early cars....

Albert, thanks for joining in! I'd be really interested to see what you come up with for a laid back radiator support. Complete inner and outer roof? This I gotta see!

I finally had the opportunity to do some real world tuft testing this weekend. I have a 70 TA that was shipped down to me to have some suspension, steering, and other work done. Before shipping it back, the owner wanted me to drive it around and put a hundred or two miles on it. He's an engineer in the fluids business so he's interested in my aero work and was kind enough to let me use his TA as a test mule. So I broke out the big ball of yarn and a roll of auto masking tape and set about covering the areas of the car I'm most interested in.

This car is almost just like mine as far as the body goes and has now been lowered to the same ride height. the tire wheel combination is very close to the same width and diameter as mine. So this gives me a great car to do baseline testing on.

I took the car up on the highway where our posted speeds are 65 MPH and ran the car between 60-70 in the slow lane, ya traffic moves right along here!

I used a Samsung 360 degree 3D virtual reality camera my bud Jeff operated for these two short you tube videos. If you have a fancy phone you can probably move the phone right/left to swing the view 360 while watching and may be able to move up/down. If you have other mobile devices like tablets/notebooks you may be able to scroll right/left for 360 viewing. If you have a 3D headset that's Oculus compatible you should be able to view in 360 3D VR.

https://www.youtube.com/watch?v=6KQA9BzpN50

https://www.youtube.com/watch?v=h6pxo5eh7Zw

Now,  once I have the video's uploaded to youtube I can play them back through the computer and through the projector to the big screen where I can see details better. Just walk up to the screen and I can watch each individual yarn tuft if I want. Tomorrow I'm supposed to have another bud join in the fun so I can get pics and video taken from another car allowing my to get shots with the car in clean air where the camera etc. don't disturb the airflow. Hopefully I'll have some nice video tomorrow to review and then discuss.

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/20160820_194054_zpscm1tawj2.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/20160820_194054_zpscm1tawj2.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/20160820_174408_zpsk3vaa90j.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/20160820_174408_zpsk3vaa90j.jpg.html)


Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 20, 2016, 11:14:02 PM
I can't remember if it's been mentioned yet, but since the '77-81 are bottom feeders wouldn't headlight covers and blocking off the bottom cutouts help?  Was just thinking about it looking at them, and then my '96 where there's not the first opening on the front end.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 21, 2016, 06:39:24 PM
I can't remember if it's been mentioned yet, but since the '77-81 are bottom feeders wouldn't headlight covers and blocking off the bottom cutouts help?  Was just thinking about it looking at them, and then my '96 where there's not the first opening on the front end.

Headlight covers work. What bottom part are you thinking about blocking off on 77-81's? 

Unfortunately my plan f getting more extensive video today didn't work out due to scheduling for ongonna try for tomorrow. I've got half the car dressed out in yarn tufts so it looks like some kind wannabe Chia car. So, it's ready whenever the planets align and we can get back out on the highway for more testing.

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/20160821_163658_zpsxbifyz1l.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/20160821_163658_zpsxbifyz1l.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/20160821_163627_zpslcyo0htj.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/20160821_163627_zpslcyo0htj.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 21, 2016, 08:19:39 PM
The cutouts where the turn signals are.

Shame couldn't get more testing done, I have to say I really like the paint on the car though.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: hakitup on August 21, 2016, 08:57:58 PM
Great stuff, I enjoy what your doing it's great to see what the air is doing.


Tom H
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 22, 2016, 10:06:18 PM
Great stuff, I enjoy what your doing it's great to see what the air is doing.


Tom H

Thanks Tom!

We hit the highway this evening for another round of video and picture taking. Here's a few still shots for you guys to ponder and comment on.  Hopefully I'll have video to review tomorrow.

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/20160822_182607_zpsr3kuxkxn.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/20160822_182607_zpsr3kuxkxn.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/20160822_182600_zpscmogizrc.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/20160822_182600_zpscmogizrc.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/20160822_182558_zpslrtvi7sc.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/20160822_182558_zpslrtvi7sc.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/20160822_182549_zpsuzotmnic.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/20160822_182549_zpsuzotmnic.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 01, 2016, 09:16:23 PM
Well the video from the 2nd go round didn't work out as well as I'd hoped it would. The video camera was too far away to see the tufts well being in a different car and the driver of the other car was trying to keep too much distance between the cars. However the regular still shots from the side give me a good idea of whats going on and I can use those pics to compare with pics of my modified car once it's back on the road.

Interesting wind tunnel video here. Shows how fairly small changes can have a big impact on lift/downforce and front/rear bias. https://www.youtube.com/watch?v=Pgpawejpi6o
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on July 24, 2017, 04:41:20 PM
Now that the dust has settled a bit with the Photobucket mess it looks like the pics I posted in this thread are somewhat safe until 12/31/18 as long as I continue paying on the Plus 20 plan I was on before the cloud of doom wiped out a lot of the 3rd party hosted pics stored in Pbucket. I'm not going to pay 400.00 a year when my old deal with them expires at the end of '18. For now, I'm going to continue using Pbucket and if any of you want to save the info with pics in this thread I'd download it before the end of 2018. If I switch the pic hosting in this thread I'll mention it in a post.

So anyway, I've been working on the under tray for my car recently and figured I'd share a few pics. The car's been completely apart until recently but I've been installing the new PTFB suspension so it's now on wheels with engine/trans installed including the side pipe headers I needed installed to work around for heat extraction. I should be able to fabricate the under tray/rear diffuser sections with the car in it's current state of assembly. Will update my regular project thread on all the cool new suspension and non aero related stuff.

It's been quite a while since I updated so here's a quick review for those who were following along or are just popping into the thread. Keep in mind I don't have any sanctioning body rules and regulations I have to adhere to.

1. Front splitter is 2 piece so I can test different lengths just by making a new (cheap) plywood section. Will be replaced later with nicer lighter permanent one piece unit once testing gets me in the ballpark.

2. Front splitter is hinged at the rear attachment point and suspended by wires in front to the bumper so it can tilt up if I hit corner curbing on road race track. I realize it may "flutter" and require me to make the front supports solid to the bumper, need to test.

3. The entire splitter, under tray, and rear diffuser will be height adjustable and quickly/easily (well fairly)  removable.

4.  There will be five sections to the whole contraption allowing me to change the heights and angles (relative to the ground) of the sections. This will allow me to adjust the entire splitter/tray/diffuser distance from the asphalt independent of the rake of the car itself. This should give me a lot of "tuning" capability. It also allows me to change different sections with different styles and sizes of diffuser tunnels and other features I might want to test.

5. The entire splitter/tray/diffuser assembly will be suspended on poles hanging from the chassis and floor of the car. This is much different than any other set up I've ever seen. Most under tray installations are bolted/screwed directly to the car and mostly sealed pretty well to the bottom of the car. My set up will allow air to freely flow between the floor and the tray from engine compartment to rear and the sides will be open. Hopefully that will allow enough heat dissipation so I don't have to add more coolers for the transmission, rear end etc.  I'm calling it the "Lab-14 Under Tray Design".  If it works well others will copy and if it doesn't work, well, it'll get tossed aside.........

6. With the splitter/tray/diffuser hanging from poles it allows me to have it set as to how far it hangs down but at the same time it can easily be pushed up if it was to hit the ground hopefully reducing the possibility of damage should I have to run over something taller than the ground clearance the tray is set at.

The problem with muscle car era Pro-Touring type cars is that there's a whole bunch of very hot exhaust stuff under the cars. That makes it really difficult to make a smooth floor attached to the body transitioning into a diffuser that actually works to help increase down force (reduce lift). It also makes it difficult to have a dual purpose car used for Auto-X or road course activities without turning the passenger compartment onto an oven if you box in the exhaust between the floor and a proper under tray. The Lab-14 Under Tray Design will allow air to flow around the exhaust removing the heat (while the car is moving) and be completely removable so folks can take it off when they're just using the car on the streets where they'd be sitting in traffic etc.  Now, while the contraption I'm building will be a bespoke combination for my particular car if the concept proves itself to work it could be used on a lot of different types of cars that are used for certain things where there aren't regulations covering what can and can not be done with splitter/under tray/diffuser. Most sanctioning bodies have very specific rules for racing classes that what limit what can be done.

The concept here is that the amount of down force or reduction in lift is determined by the pressure difference between the upper and lower surfaces of the vehicle. The air pressure between the floor and under tray of my design should have a (relatively) similar pressure difference applying up and down so it doesn't change the amount of grip the car has just like having the windows of the car open or closed doesn't really change the amount of grip by any measurable amount. Meanwhile the very high speed air under the tray will have less air pressure pushing up on the tray (Think of it as a slight suction increasing the weight each tire receives).  The combined area of the splitter/tray diffuser I'm making is roughly 11,000 Sq. In. so a change in air pressure of .1 lb (sea level is about 14.7 Lb) would result in an increase in down force (reduction in lift) of over 1000 lbs.  That would result in a tremendous difference in cornering capability so even if I don't get anywhere near that the whole project might be worthwhile. If nothing else I'll learn something even if it's that my idea doesn't work.

On to some pics! This one shows the splitter and how it hinges on the tubing inside of the box tubing as well as the tubes inserted in the sub frame. The vertical  aluminum tubing will have holes drilled through it that a spring clip gets inserted through so I can set the splitter at different heights. I was trying to use up old scraps of stuff to make my test pieces so thats why there's panel sections in the tray part under the engine. If everything works I'll make nicer lighter pieces later on after testing.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/20170723_172516_zps8imnoete.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/20170723_172516_zps8imnoete.jpg.html)

Toward the rear of the engine compartment there is another set of vertical tubes welded to the sub frame for aluminum height tubes to slide into like the ones at the splitter along with another hinge set up where the panels join. This separates the engine section from the section under the cowl area.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/20170720_183000_zps3wglxo62.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/20170720_183000_zps3wglxo62.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/20170723_171456_zpsxaaahkrf.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/20170723_171456_zpsxaaahkrf.jpg.html)

There will be a set of height tubes in the cabin by the base of the A pillar and another set in the rear seat footwell. They will function similarly to the ones in the engine compartment except that instead of being welded in place they will be inserted through the floor of the car through a rubber grommet. The steel tubes have a washer welded to them preventing them from sliding down. I will make some caps that insert into the grommets for when I don't have the under tray installed. The aluminum tubes will function the same with a spring clip holding them up and still allow the tray to rise if necessary. I made a set for the rear supports in the trunk also.  These will allow quick changes to the height and pitch of the under tray from splitter to diffuser without having to go under the car.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/20170723_180715_zpsupbuxmzw.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/20170723_180715_zpsupbuxmzw.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/20170723_181138_zpsnczo98he.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/20170723_181138_zpsnczo98he.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy/20170723_180859_zpsyltq0yn5.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy/20170723_180859_zpsyltq0yn5.jpg.html)



Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on July 26, 2017, 10:34:05 AM
I guess it's time for an update, as a lot has changed on the car since I first posted my build. This is a truncated version of the post in my build thread, whittled down to just focus on aero and related mods.

Update 1: Brake Hubs and Wheels. I sold off my spindles and Kore3 conversion hubs and brackets to buy new spindles that allowed me to put C6 hubs on the TA. A friend has a sideline business parting out wrecked C6s, so I go the hubs cheap ($25 each, with 20k miles). This gained me a better, leak-free hub design, in addition to the lower operating costs. Since taking these pics, I fabricated dust shields with provisions for brake cooling ducts. I also made a tenmplate that can be printed out on 8.5x11 paper and traced onto the steel plate of your choice. Pics of both coming later. In the meantime, spindles:
(https://cimg3.ibsrv.net/gimg/ls1tech.com-vbulletin/634x357/80-hub2_2fcd154a554afa331a6bb63e6be5dd1128d909ed.jpg)
(https://cimg5.ibsrv.net/gimg/ls1tech.com-vbulletin/634x357/80-brake2_1d3a0cb70c0974e57296264aa8318314e95fc0b7.jpg)

Update 2: Aero: If you look back in this thread, I had a short splitter and was making the argument with a buddy for a longer one. I got lots of great input, and I won the argument, but one thing I didn't consider at the time was needing to stay within SCCA rules. CAM wasn't that big of a deal, as the rules are still pretty loose. However, if I wanted to run slicks, the car would probably end up in one of the hairy Street Prepared classes.

In a nutshell, I could have a splitter, but I needed to stay within the rough outline of the car, as viewed from the top. No long beaks sticking out the front :-) . I also could not extend the splitter beyond the halfway point of the front axle. Side and rear aero is still being planned. I'll certainly mooch off Not A TA's ideas above :-) and also copy the idea of extending the rear spoiler that was illustrated earlier in this thread.

For the front, in practical terms, this meant the splitter's rear edge was about 1" forward of the centerlink. Here is the result. One thing I am contemplating is relocation of the brake cooling inlets to the area above the splitter and then placing smoked lexan in front of the upper grill/headlight area. Opinions?
(https://cimg6.ibsrv.net/gimg/ls1tech.com-vbulletin/1063x598/80-splitter_7619a69c337cadfabc801113b4136b9a996a9b6d.jpg)

I've only blocked off maybe a foot of the open space above the splitter, at the very ends (the area directly in front of the tires). The rest of the area remains completely open -- I've never had the insert that goes below the bumper, so I get to make one out of scrap aluminum sheet from a local circle track fabricator.

Update 3: underhood air direction: I blocked off the open area between the top of the core support and the car's nose with a 1/4" smooth ceiling tile at Menards. Air coming in from the grill and bottom feed is now forced through the radiator, air intake or oil cooler. Water temps remain the same as before, but I've noticed that the car will not need the radiator fan to assist with cooling above 20 mph. Before I blocked this space off, that number was more like 35 mph.

When moving, the water temp never exceeds 185 degrees, even in hot weather or racing. The worst spikes come from driving in heavy stop-and-go traffic.

I'll try to get pics of all this posted tonight.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 13, 2017, 09:21:08 PM
Karl, You can get the air for the brake ducts anywhere from the core support forward. They don't need to be facing directly forward into oncoming air. If you take it from down near the splitter you're taking away some of the pressure you want on top of the splitter. If you take it from up high near the hood (but behind the grills) you'll be taking air reducing lift on the underside of the hood/upper bumper cover. Seems like the first choice to make would be whether to make it a bottom breather or front. Drag guys have found higher top speeds with the upper grill/headlight blocked with plexiglass.

Your top of radiator block off is working well as you noted. Do you have any pics of the closeout?

The splitter should work much better than the other one. You may notice the back end feels loose compared to the front until you put a taller rear spoiler into effect because the splitter and tray in front will move the center of pressure forward until it gets balanced by something in the rear. Initial turn in will be better but then as the pendulum effect starts mid corner the rear might feel loose. I'd put a rear spoiler extension right to the limit of the rules for auto-X. And make it tall all the way out on the sides, more like Camaro spoiler ends, kinda squared off. Might be too much drag for road track use though.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 13, 2017, 09:31:49 PM
Here's a couple more pics of my contraption laid out in the driveway so you can get a better idea of what I'm doing. Still need 4 more support rods and a couple sticks of box tubing as well as some aluminum sheet, but it's coming along! The big white sheets are a couple different thicknesses of corrugated plastic. With side pipes I don't have heat/melting issues from about the front seats back in the middle of the car. The curved up section at the rear is measured to be pretty close to what the actual diffuser will be when finished.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170811_184019_zpsmhzay6bw.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170811_184019_zpsmhzay6bw.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170811_183957_zpsz18ojxpu.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170811_183957_zpsz18ojxpu.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on August 14, 2017, 05:13:41 AM
Kinda Neat John but I find it also Insane.

Top Speeds Gains are easily solved with a Cubic inch Bump.
And Turbo Charging or Supercharging.
No need to go beyond 462 cubic inches today.
480 ci Drag Racing Twin Turbo Charged.

That setup comes free Your areo mods it may destroy you car.
Just my 2 cents.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on August 14, 2017, 05:15:13 AM
Bonneville Salt Flat cars use on Giant Belly Pan.
Worked for Mickey Thompson going 406 mph.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 14, 2017, 08:18:38 PM
Kinda Neat John but I find it also Insane.

I'm sure you're not the only one. I've done a lot of things where I was ahead of the times. This may be another case, OR, you may be right.

Top Speeds Gains are easily solved with a Cubic inch Bump.
And Turbo Charging or Supercharging.
No need to go beyond 462 cubic inches today.
480 ci Drag Racing Twin Turbo Charged.

All of those things ^^^ require considerable amounts of cash and make the car less reliable. I try to get the most performance with the minimum of things that can go wrong.

That setup comes free Your areo mods it may destroy you car.
Just my 2 cents.

Like we tell everyone else "It's your car do whatever you want with it." The aero mods may also take it to cornering levels where no 2nd gen has been.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 14, 2017, 08:37:02 PM
Bonneville Salt Flat cars use on Giant Belly Pan.
Worked for Mickey Thompson going 406 mph.

Although I took my car to Land Speed Races in the past and will likely do so in the future the splitter/under tray/diffuser in the pics above is for road course type use for cornering. I'll have a different aero set up for Land Speed Race use with less down force and less drag.

 
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on August 14, 2017, 10:09:40 PM
Bonneville Salt Flat cars use on Giant Belly Pan.
Worked for Mickey Thompson going 406 mph.

Although I took my car to Land Speed Races in the past and will likely do so in the future the splitter/under tray/diffuser in the pics above is for road course type use for cornering. I'll have a different aero set up for Land Speed Race use with less down force and less drag.
If You Can TIG Weld it together the Main Aero Under body frame it would be the strongest.
Or find someone close by that can do it.
If you were in Illinois my Bud Ed could do it for You.
He is self employed and doing Drag racing chassis work now.
Custom builds Fuel cells from Stainless and aluminum.
Roll Bars.
Back Halving cars.

6 - 8 drop down supports needed looking and thinking.
Doing the Chaperal Thing I know.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on August 14, 2017, 10:12:47 PM
Kinda Neat John but I find it also Insane.

I'm sure you're not the only one. I've done a lot of things where I was ahead of the times. This may be another case, OR, you may be right.

Top Speeds Gains are easily solved with a Cubic inch Bump.
And Turbo Charging or Supercharging.
No need to go beyond 462 cubic inches today.
480 ci Drag Racing Twin Turbo Charged.

All of those things ^^^ require considerable amounts of cash and make the car less reliable. I try to get the most performance with the minimum of things that can go wrong.

That setup comes free Your areo mods it may destroy you car.
Just my 2 cents.

Like we tell everyone else "It's your car do whatever you want with it." The aero mods may also take it to cornering levels where no 2nd gen has been.
455 Shortblock. Reuse Your 16 Heads, ISKY Race Cammed flat tappet solid.
Spank LSX & New C7 Vettes.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on August 14, 2017, 10:15:39 PM
4130 Roll bar tubing lighten things up too some.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Dreamn2 on August 15, 2017, 02:42:02 PM
Since taking these pics, I fabricated dust shields with provisions for brake cooling ducts. I also made a tenmplate that can be printed out on 8.5x11 paper and traced onto the steel plate of your choice. Pics of both coming later. In the meantime, spindles:
(https://cimg3.ibsrv.net/gimg/ls1tech.com-vbulletin/634x357/80-hub2_2fcd154a554afa331a6bb63e6be5dd1128d909ed.jpg)
(https://cimg5.ibsrv.net/gimg/ls1tech.com-vbulletin/634x357/80-brake2_1d3a0cb70c0974e57296264aa8318314e95fc0b7.jpg)


Can you still post the dust shield templates?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: skisix38off on August 16, 2017, 06:51:28 AM
In the meantime, spindles:
(https://cimg3.ibsrv.net/gimg/ls1tech.com-vbulletin/634x357/80-hub2_2fcd154a554afa331a6bb63e6be5dd1128d909ed.jpg)
(https://cimg5.ibsrv.net/gimg/ls1tech.com-vbulletin/634x357/80-brake2_1d3a0cb70c0974e57296264aa8318314e95fc0b7.jpg)

What spindles are those?  Do they help any with caster?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 16, 2017, 10:33:13 AM
Any new super cars have smooth bottoms through panels that bolt to the underside.  Here's the underside of a McLaren P1 for instance:
(https://motortorque.org/wp-content/uploads/2015/05/McLaren-P1-under-body-26.jpg)

I think it's a good idea to experiment upon, obviously it's proven to work when done right.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on August 16, 2017, 06:34:45 PM
The C7 Z06 does 198-202 MPH Top end with 650 HP.
The C8 is supposed to have 750 HP. Wont see it till maybe next year.
The Fat Pig Hellcats also run 198-202 Mph Top End with 707/ actually 780 Flywheel HP.

Going to take HP no matter what.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on August 16, 2017, 07:26:44 PM
Well yes eventually you hit a top speed wall either via power, aerodynamics, or gearing, but the more aerodynamic the less power needed.  The fourth gens with the 6-speed were capable of 160-170 mph new with only 300 horsepower since they're so aerodynamic.  The McLaren F1 back in the early 90's had a top speed of over 240 mph but only had 627 horsepower, so aerodynamics are a huge factor.  I think he's on to something, there's a lot of room for improvement on most any mass produced car and especially on one that's older.  People successfully do aero mods on all kinds of cars all of the time either seeking increased fuel efficiency or better performance on the track, so it's worth investigating.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on August 16, 2017, 07:49:58 PM
Well yes eventually you hit a top speed wall either via power, aerodynamics, or gearing, but the more aerodynamic the less power needed.  The fourth gens with the 6-speed were capable of 160-170 mph new with only 300 horsepower since they're so aerodynamic.  The McLaren F1 back in the early 90's had a top speed of over 240 mph but only had 627 horsepower, so aerodynamics are a huge factor.  I think he's on to something, there's a lot of room for improvement on most any mass produced car and especially on one that's older.  People successfully do aero mods on all kinds of cars all of the time either seeking increased fuel efficiency or better performance on the track, so it's worth investigating.
John Birdman will follow through. I know him from another forum.
Drag cars rely upom Aerodynamics too.
Likely what happened when that 5.0 Stang cut into Big Chief and His Crow GTO a few years back.
Its risky business testing Areodynamics.
A wind tumnel blowing 150-200 mph wind speeds be nice to use.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: roadking77 on August 17, 2017, 08:50:19 AM
John, I too think you crazy!(in a good way) But love what youre doing with that car. My brother races motorcycles, and his mentor/racing buddy is always doing something to get that extra bit of power of his bike. My brother told him to skip a couple of beers instead! They guy is german, over 6 ft, and must weigh well over 250lbs.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 18, 2017, 12:44:24 PM
As I mentioned back on page 1 of this thread, I'd like this thread to remain focused on aerodynamics of 2nd gen TA's for any kind of use.  Whether it's drag racing, road racing, Auto-X, Land Speed, hypermiling aero aids,  or just ways to make the car quieter in the cabin for daily drivers and Sunday cars. Why GM installed Astro Flow Through Ventilation and other topics like mirrors, drip rails, side window blow out clips, external antenna and other items can all be discussed as long as we remain focused on 2nd gen aero.  If anyone wants to discuss how much power it takes to achieve certain speeds or ET's, mechanical grip with modern suspensions, aero stuff about 1st, 3rd, 4th gens etc. please start another thread to cover your topic. I will happily participate having personal experience with all gens.

If anyone's tested various aerodynamic things to change the performance of 2nd gens whether it worked as hoped or not please share it in this thread. We can all learn from what others have tried.

My contraption might seem a bit crazy to many. However although I put an engineering disclaimer in my first post I've been involved with aero/fluid dynamics for a long time. The basic concepts used for the Lab-14 Under Tray Design are proven. Where the Lab-14 design differs is the mounting method of it being suspended on rods, being (relatively) quick release,  and the sides above the tray being open rather than sealed to the bottom of the vehicle. I have a series of articles I've been writing with more details about this splitter/under tray/rear diffuser that include short stories about some of the more memorable aero experiences I've had if anyone is interested.  Part of the reason I started posting the articles on linkedin is because the pics I've posted in this thread will probably disappear when my Photobucket 3rd party hosting agreement ends and the linkedin article will remain intact. https://www.linkedin.com/pulse/height-adjustable-rake-fully-suspended-multi-section-quick-john-paige
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 20, 2017, 08:30:25 PM
I've been working on the under tray and have the part from the A pillars to the rear foot wells ready for test fitting and some final tweaking in the area where the side pipe headers are. Currently working on cardboard mock up of the rear diffuser section.

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170917_120349_zpsmlqlqnq2.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170917_120349_zpsmlqlqnq2.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170917_191700_zpsemnmtv22.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170917_191700_zpsemnmtv22.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170919_192722_zpsuj4lsngc.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170919_192722_zpsuj4lsngc.jpg.html)

 
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on September 25, 2017, 05:36:07 PM
(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_174457_zpsbauyzlbo.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_174457_zpsbauyzlbo.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_174611_zpsrnwrah6j.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_174611_zpsrnwrah6j.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_182200_zpskioa0kdi.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_182200_zpskioa0kdi.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: FormTA on September 25, 2017, 09:21:06 PM
What is that surf board going to weigh? It's neat all of this aerodynamic testing. Some major forward thinking. Just curious as to the weight addition. To me blocking off the sail that is the under car should prove beneficial.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on September 26, 2017, 05:16:36 AM
(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_174457_zpsbauyzlbo.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_174457_zpsbauyzlbo.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_174611_zpsrnwrah6j.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_174611_zpsrnwrah6j.jpg.html)

(http://i240.photobucket.com/albums/ff292/NOTATA/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_182200_zpskioa0kdi.jpg) (http://s240.photobucket.com/user/NOTATA/media/The%2014%20Car%20Performance%20Therapy%20part%202/20170923_182200_zpskioa0kdi.jpg.html)

It looks pretty neat John from the back view.
Like Rocket Boosters.

What would be really fun is spraying gasoline out them with a Snow Performance Methanol injection pump or windshield washer pump.
Ignite with a spark plug & Model T ignition coil.

Thinking of the F-Bomb Camaro.
It was very radical too.

Have to paint some custom graphic on the sides.
Use John C, In NY.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on January 10, 2018, 01:45:09 PM
Egads, it's been forever since I took some time to research things at TAC, and it looks like I've got some catching up to do. I will post the backing plate template and a pic of the upper core support block off tonight when I get home (sorry it took so look to see this). My Spindles are from CPP, model CP30014.

I *may* also get a set of 3rd gen side aero bits in a trade later this month. I'm thinking about seeing how well I can get them to work on a 2nd gen without looking stupid. Thoughts on this idea?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on January 11, 2018, 12:07:03 AM
Block off:

(https://cimg2.ibsrv.net/gimg/ls1tech.com-vbulletin/492x733/80-block_off_6d454422bf8cb783e106727a123ec9b821a90400.jpg)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Jack on January 11, 2018, 07:49:41 AM
My contraption might seem a bit crazy to many. However although I put an engineering disclaimer in my first post I've been involved with aero/fluid dynamics for a long time. The basic concepts used for the Lab-14 Under Tray Design are proven. Where the Lab-14 design differs is the mounting method of it being suspended on rods, being (relatively) quick release,  and the sides above the tray being open rather than sealed to the bottom of the vehicle. I have a series of articles I've been writing with more details about this splitter/under tray/rear diffuser that include short stories about some of the more memorable aero experiences I've had if anyone is interested.  Part of the reason I started posting the articles on linkedin is because the pics I've posted in this thread will probably disappear when my Photobucket 3rd party hosting agreement ends and the linkedin article will remain intact. https://www.linkedin.com/pulse/height-adjustable-rake-fully-suspended-multi-section-quick-john-paige

Great article John, following you on LinkedIn as well.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on January 11, 2018, 05:34:59 PM
I've been working on the under tray and have the part from the A pillars to the rear foot wells ready for test fitting and some final tweaking in the area where the side pipe headers are. Currently working on cardboard mock up of the rear diffuser section.


That looks like a pretty serious diffuser.  How far does it extend past the rear bumper? Do you expect any impact on fuel tank location? Or watts link?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on January 11, 2018, 08:34:32 PM
The cardboard diffuser in the pics is actually oversize on purpose so I can cut it down to fit rather than try to make one from measurements with the car on the ground. If it was as big as it is in the pics I'd probably (almost certainly) experience a loss due to stall. With 3" ground clearance to pavement at the entrance to the diffuser the area ratio is way to high (at 7.3) for a diffuser that wasn't designed using CFD and/or wind tunnel testing. I'll make sure I'm below a ratio of 5 when I can get the car on the ground at ride height and get some final measurements for diffuser construction. The curvature is within tolerances so the flow will stay attached.

The diffuser should clear the gas tank and I re-positioned the sway bar mounting to the axle tubes instead of the bottom of the shock plates the way the stock bars mount to provide additional clearance for the diffuser tunnels and reduce drag when I don't have the under tray assembly on the car. Will post pics of the sway bar mount modification when I get the pics uploaded, I'm waaay behind.

I contemplated a block off panel similar to yours instead of the rubber seal I installed and if air pressure blows my seal out (which is quite possible) I'll make a panel like yours. Have you blocked off the other areas where air can get past the core support?

I believe the air coming in under the sides of the car at the rockers is detrimental and probably reduces the speed of air under the car increasing lift/reducing down force.   You can see in the tuft test pic below how the air flow below the body line angles down getting pulled in under the car while above the body line the tufts point straight back. The rocker extensions from the 3rd gen would probably reduce that if you can fit them and they're legal for whatever class you run in. During the ground effects era of the late 80's early 90's F1 cars had sliding skirts that literally slid along on the pavement that were eventually banned. I will be installing skirts on the sides of my under tray to help keep air from entering but will maintain a gap to pavement for safety reasons.

Jack, thanks for following on Linkedin.  Reminds me I need to write articles there about some municipal water and wastewater projects I've been doing designs and fabrication of for regular work. Car stuff and aerodynamics is more "fun" to me but today I was designing a Vortex Butchering Basket for vertical turbine pumps used by municipalities so that's kinda cool (well to me anyway) and helps pay the bills.

(http://i240.photobucket.com/albums/ff292/NOTATA/AERO/20160822_182556_zpsxk7owkl5.jpg) (http://s240.photobucket.com/user/NOTATA/media/AERO/20160822_182556_zpsxk7owkl5.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Box on January 11, 2018, 08:47:46 PM
People make skirts and body aero out of the plastic garden edging stuff you get from Home Depot or Lowe's, since it's dirt cheap and easy to work with.  That and it's impact resistant while still maintaining its shape, and if you do break it or drag it off it's cheap and easy to replace it.  Comes in a variety of widths to suit what's needed in a given application.  At the very least would be good to experiment with before developing parts in metal or fiberglass.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on January 11, 2018, 09:51:20 PM
What is that surf board going to weigh? It's neat all of this aerodynamic testing. Some major forward thinking. Just curious as to the weight addition. To me blocking off the sail that is the under car should prove beneficial.

Sorry I missed this question back in Sept.  The whole contraption that will be used for testing is just over 100 lbs. If it works well I'll make a lighter version and think I could get down to 50-60 lbs without using carbon fiber. If my disposable income level rises and I could go with some carbon sheets etc. I think I could get down under 50 lbs. Most higher end race cars now have one big flat carbon fiber sheet now. You can see it in these pics of a Mercedes AMG World Challenge car I got to poke around.

Sticking out the sides below door in pic below to reduce air getting under the car and perhaps also create a virtual seal with a vortice. The aerodynamicists that worked on it would know.

(http://i240.photobucket.com/albums/ff292/NOTATA/AMG%20SLS%20GT3/006_zpszxfs7yca.jpg) (http://s240.photobucket.com/user/NOTATA/media/AMG%20SLS%20GT3/006_zpszxfs7yca.jpg.html)

You can see the flat carbon fiber sheet in pic below under the air jack.

(http://i240.photobucket.com/albums/ff292/NOTATA/AMG%20SLS%20GT3/009_zpsn3ybid3k.jpg) (http://s240.photobucket.com/user/NOTATA/media/AMG%20SLS%20GT3/009_zpsn3ybid3k.jpg.html)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on January 11, 2018, 09:55:11 PM
People make skirts and body aero out of the plastic garden edging stuff you get from Home Depot or Lowe's, since it's dirt cheap and easy to work with.  That and it's impact resistant while still maintaining its shape, and if you do break it or drag it off it's cheap and easy to replace it.  Comes in a variety of widths to suit what's needed in a given application.  At the very least would be good to experiment with before developing parts in metal or fiberglass.

Yes sir, hypermiler's use it as well as race car guys. Another cheap material for skirts is conveyor belt material.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on January 11, 2018, 10:26:11 PM
The exhaust headers create Immense amounts of heat Road racing and drag racing John.
Have to get that heat out or the engine oil temps will really skyrocket.
Without an engine oil cooler the engine will not last then.  Hit 300F or more oil temps is not good.
Only True Straight 50-70 weight Racing oil will take that kind of heat.  Used In Nirto Drag Racing usually.
Dirt track racing 900-1000 HP level also.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on January 11, 2018, 10:29:10 PM
I do like the Surf Board.
Looks like nothing else.

I would not put it on 1970 TA though. Like it as is .
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on January 11, 2018, 10:34:59 PM
If things get tough John you can use Aviation Piston engine oils in a Pontiac V8.
I have tried it out.
Aero Shell.

Works great in Air Cooled Harley Davidson engines.
Superior to most Auto oils.

A entire another topic.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on January 12, 2018, 12:07:58 AM
I contemplated a block off panel similar to yours instead of the rubber seal I installed and if air pressure blows my seal out (which is quite possible) I'll make a panel like yours. Have you blocked off the other areas where air can get past the core support?

Not quite yet. When It gets warmish enough, I'll venture out into the garage to correct the gaps depicted in the below under-hood shots :-)

The bottom shot attempts to show what I have going on in front. Most of the air entering the left marker light hole is forced through the oil cooler and out through the gap between the core support and driver side fender. Both grill sections by the headlights are blocked, so the only air entering the engine bay from the front comes through the bottom feed and marker light holes.

(https://cimg5.ibsrv.net/gimg/ls1tech.com-vbulletin/374x664/80-radiator_right_3e596a1651e3386624e91120568e3b8073eb09f6.jpg)

(https://cimg8.ibsrv.net/gimg/ls1tech.com-vbulletin/374x664/80-radiator_left_7526abbfc979cab131707ec1886dded002fd5bc5.jpg)

(https://cimg6.ibsrv.net/gimg/ls1tech.com-vbulletin/664x343/80-radiator_center_front_aa893c859e9f5936fe76b172714965ed18bf47b9.jpg)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Dreamn2 on January 17, 2018, 09:28:31 AM
Have you guys done anything for rear brake cooling ducts?
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 79T/Aman on January 17, 2018, 11:38:22 AM
Have you guys done anything for rear brake cooling ducts?

Not sure the rear brakes need anything much unless it is a roar race car that is going to do more laps than your average track day but I'm sure John will be all over it :-)
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on January 17, 2018, 05:33:35 PM
I share my car with a friend who happens to be a track day instructor. Its one od those arrangements where you get free track time in exchange for instructing. We had an event last fall at Gingerman where the student's car developed mechanical problems the day before. Rather than letting the guy get screwed out of his entry fees, we made the Trans Am do double-duty. So, instead of the usual 20 minutes on and 40 to 60 minutes off, it was 20 on, switch drivers, 20 minutes on again, 20 off.

The rear brakes had no issues during this day, and in fact remained on the car as I drove it home 3 hours afterward. Front brakes needed the pads switched out, and besides a LOT of heat, were ok.

So, I'd say rear cooling ducts probably aren't needed unless you're going to do an endurance race.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on January 17, 2018, 06:43:13 PM
I have not been around road racing much at all but I have been around lots of Dirt track racing here in Illinois.
Tracks here are 1/4 mile High banked Clay Oval, 1/2 mile Flat tracks.
1 mile long, Springfield mile.
Springfield mile allows for 140 + mph speeds on dirt.
Cars have no windshields because rocks thrown up from the track will knock break them out.

More than once I have seen the rear brakes glowing red to white hot incandescent after 50-250 lap races.
Front brakes too.
Drivers are on the brakes hard to slow down into the corners.
You can see it happen sitting in the Grand stands.

Everything from Hornet 4-bangers to Street Stock V8, to Unlimited super late model packing 750-900 HP Normal aspirated SBC V8 engines.

Forced air cooling can not hurt anything.
Front or rear.




Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on January 17, 2018, 06:46:22 PM
Have you guys done anything for rear brake cooling ducts?

Not sure the rear brakes need anything much unless it is a roar race car that is going to do more laps than your average track day but I'm sure John will be all over it :-)
You should come over to the Vette forum with me.
The Guys will like your antics & comments.
We are a rough bunch of guys.
The Mods Love me there.

Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on January 17, 2018, 07:00:19 PM
The exhaust headers create Immense amounts of heat Road racing and drag racing John.
Have to get that heat out or the engine oil temps will really skyrocket.
Without an engine oil cooler the engine will not last then. 

Agreed, my tray system allows air to flow freely out between the tray and floor of the car which will hopefully keep things cool enough so I won't need additional coolers for engine oil, rear end, etc.   I will be running Hooker side pipes and the area of my tray under the headers and side pipes is aluminum.

My tray system is easily removable so the car can look normal anytime I want as opposed to under trays, splitters, and diffusers that are fastened directly to the car.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 70RAIV455 on January 17, 2018, 07:03:00 PM
The exhaust headers create Immense amounts of heat Road racing and drag racing John.
Have to get that heat out or the engine oil temps will really skyrocket.
Without an engine oil cooler the engine will not last then. 

Agreed, my tray system allows air to flow freely out between the tray and floor of the car which will hopefully keep things cool enough so I won't need additional coolers for engine oil, rear end, etc.   I will be running Hooker side pipes and the area of my tray under the headers and side pipes is aluminum.

My tray system is easily removable so the car can look normal anytime I want as opposed to under trays, splitters, and diffusers that are fastened directly to the car.
OK John.
I just don't want see you have any mechanical issues.
Sharing my knowledge with You.
It just may work your ideas.
Go For it my friend.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on January 17, 2018, 09:02:42 PM

Not quite yet. When It gets warmish enough, I'll venture out into the garage to correct the gaps depicted in the below under-hood shots :-)

The bottom shot attempts to show what I have going on in front. Most of the air entering the left marker light hole is forced through the oil cooler and out through the gap between the core support and driver side fender. Both grill sections by the headlights are blocked, so the only air entering the engine bay from the front comes through the bottom feed and marker light holes.

The area in front of the core support becomes a pressurized box at speed. The sides by the fenders needs to be blocked off (and any other openings to the engine compartment) in order for the block off you installed on the top of the core support forward to be effective. Ideally you want to seal off the front either at the core support so there is a sealed pressurized area forward of it OR by using ductwork that confines airflow from the nose to the radiator/oil cooler and brake ducts. The radiator should be sealed to the core support (or duct to bottom feeder opening) so no air can get around it.

Essentially you want to seal off the front of the car so air goes over, under, or around the car except air used for cooling things.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on January 17, 2018, 09:25:20 PM
Have you guys done anything for rear brake cooling ducts?

I'm not putting any on my car currently but have plans to monitor brake temps once I get the car back on track. I'll probably only be on track 20 minutes at a time and have huge (for rear) 14" discs so I don't think I'll have a need for rear ducts. If I was still running stock drums out back I'd probably run some ducts for track use.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1981RoadRace on July 19, 2018, 06:28:59 AM
Hi guys, it's been a while since I've been on (I need to fix all my pics), but I ran across a CL posting that would be if interest in this thread. Check out the aero on this guy...
https://flint.craigslist.org/cto/d/pontiac-455-super-duty-power/6639965511.html
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: FormTA on July 19, 2018, 06:48:20 AM
Neat, interesting car.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: roadking77 on July 19, 2018, 07:13:06 AM
Yea, there was quite a polarizing thread on PY forum about that car. It has an interesting history.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: Jeremy on August 07, 2018, 08:00:53 PM
After reading through the thread, I worked on blocking all openings in front of the core support to force all of the air through the AC condenser and the radiator.

It made quite a difference in the efficiency of the AC.  Before, it would cool the cabin, but just barely.  After sealing off the front, the AC was cool enough that my son asked me to turn down the blower.

The engine also ran cooler with the AC on.  Before sealing everything, the engine would creep up to 200-205 in town and come back down to 190 on the highway.  The highest I saw today was 186 in town and it stayed 183 on the highway.

When you get to looking, there are quite a few openings in the core support.  I was surprised.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: NOT A TA on August 07, 2018, 08:19:14 PM
Thanks for the feedback Jeremy! 

 Because I get so focused on  performance things like engine cooling, brake cooling, increasing down force etc. I don't think I ever mentioned the benefits for AC or automatic transmission coolers.
Title: Re: 2nd gen TA aerodynamics and modifications
Post by: 1976 SE SF on November 22, 2018, 10:41:19 PM
This post is the best thing about I've ever read