How to get an extra 100 HP from this build

[SoupMan]

Guys,

Lots of people on this forum influenced my build over the years. This was highly recommended for a budget build since it allowed me to get to my original objective of 400 BHP. The engine dyno test originally gave me 406 HP and 512 ft/lb. I'm trying to get my hands on my dyno sheet since they never provided it. Long story short, I got to see it on screen but never got the promised printouts emailed to me.

When I first got the car together the power was significantly more than the suspension and braking could handle. I have since done:
- 10" rubber in in the rear
- C6 front brakes
- New front UMI springs and KYB shocks
- New rear BMR leafs and KYB shocks
- Champion 3 row core radiator
- TH350 built for 650+ (guess we will find out)
- 10 bolt rear end, non locking. Looking to go truetrac or something like that
In the works:
- Frame connectors
- Rear brake from Drumbos to something better

I would like to get around 520 HP and closer to 600 ft/lb on pump gas. My budget isn't set. That's why I'm poking around trying to figure out if there are fundamental things that could have been done in the original build to bump me up. Of course, I've had some Chevy guys tell me that cam is too conservative and that I could squeeze 50 more HP but I'm skeptical.


The build originally included the following (I included everything I though was relevant):
- Full rebuild machine work (Bore, tap, crank polish, desk, balancing). These guys are known for good machine work. They however are not Pontiac specialists
- Pontiac 455 Block (1976 stamping)
- 6x-8 heads
- Holey EFI 4150
- Hooker headers 1 3/4 tubes, 3" collector, ceramic coated
- 2.5" dual exhaust
- COMP CAM 51-224-4 (274/286, Lift .488/.491)
- COMP CAMS - Valve Springs - 995-16
- COMP CAMS - Pushrods - Custom
- COMP CAMS - Rocker Arms - 19061-16 (1.65 ratio)
- COMP CAMS - Timing Kit - 3112
- VTI - Lifters - VL49-16
- BOP - Rear Main Seal - RM501
- MAHLE - Pistons - 224-1849-030
- ARP - Rod Bolts - 190-6001
- ARP - Main Studs - 194-5401
- ARP - Head Bolts - 190-3607
- ARP - Rocker Arm Studs - 290-7201

[5th T/A]

Not knowing what your plans and goals for how this car will be driven makes it a little harder to offer suggestions. Is this for street cruising, autocross or drag racing at the strip?

Increasing power can come with head work, different intake manifolds, port matching, wilder cams and better flowing exhaust systems. If the car wasn’t tuned properly you can pick up a little more with jetting and playing with ignition timing and advance curves. Since the engine is in the car I would suggest a chassis dyno test to establish a baseline before making any modifications so you can measure any gains.

Switching from an open differential to a posi will definitely help you get power to the ground. Honestly with an open differential traction really sucks, just changing to a posi will make a big difference. Choosing an appropriate axel ratio based on how the car will be driven is important.

Other TAC members can provide more useful information than me. Mentioning how and where the car will be driven will help them guide you. If you don’t get good answers from here try maxperformanceinc website. They have a lot of member into really building their cars.

[Bluebandit]

Air in and out makes power, a good set of heads and larger cam will get you started. You didnt mention what intake and mufflers you are using, that would help.
As 5th T/A mentioned, a good tune will find power if it hasnt been done

[Wallington]

Chevy guys know what's best, even if they don't know what a 455 is!
Often power comes at the cost of driveability on the street.

[SoupMan]

5th,

Silly me, forgot to put my objectives.  As for a baseline dyno that's on the list already.

Street mostly. Would love to bring it to the strip eventually just for fun and to see what it can do. But I'm not a weekend warrior or anything like that.
As for the intake manifold, it's an edelbrock. I need to double check exactly which one I have. Torquer if I recall.
Exhaust is dual 2.5" a Pypes with their Race Pro muffler.
The rear gear is 2.72.

Some of the things I've contemplated at doing:
- Matching my cam to my rear end. Would like to go to 3.43 or something in that range and a locking rear end
- To keep the car fun on the highway since I drive it a lot, go to a 200R4 or 4L80
- A good tune will probably help this build feel better and getting a wheel dyno is in the plans in the spring
- A turbo or supercharger?

[nas t eh]

The problem with 500+HP and the matching torque of 550+ you will get from your 462 is that you start finding all the weak links and have to fix them one by one.

Is you oil system up to the task. Oil pump, bearing clearances and oil pan. Large journal Pontiacs have the potential for oil starvation unlike many other motors.
Is you rear end going to handle the power? A BOP 10bolt is going to have a hard time if you put posi and sticky tires on it.
In the motor it looks like you used stock rods with ARP bolts? less than ideal and you need to keep the rpm down, this is fine with the cam and heads you have as max power and torque are probably happening under 5000rpm, But if you go aluminum heads and roller cam that would change and then you may find the rods are unhappy.

[SoupMan]

Nas,

You are correct.

I was under the impression these blocks + crank were good for about 700 HP. So what I'm understand is the rods will get me to 450 but I'm playing with fire above that. Pardon my ignorance but if I pull the motor and do rods and whatever necessary oil changes I need to do, am I look at machine work or I'm getting into something I can do on the bench?

The oil pump is a MELLING M54DS which I believe is a stock spec.

[nas t eh]

I've lost the rod bearings on two different 455's so for me, Rods and oiling are important.

I followed HO Racing Specialties recommendations on Oil control when I built my current motor, There have been many new and improved ideas since, but there are also a few basic things.

1. A good quality RA4 or 455SD style oil pump with the thick bottom plate and a 60lbs relief spring or higher if spinning the motor up over 6000rpm. Lots of guys say 60 is enough and going to 70-80-90 just wastes HP and wear on the cam and oil pump gear. But Pontiac put an 80psi spring in the 455SD oil pump for a reason. And you have a large journal 455 not a small journal 400 with a stroker crank.
2. The crank ground for proper oil clearance and the oil passageways on the main and rod bearing chamfered correctly.
3. Forged rods.
4. Oil control at the lifters and rockers so they don't take too much from the bottom end, (the best new way for this is restrictors in the pushrods.)
5. Oil pan for the type of driving you do. I like the Canton Road Race pan and a crank scraper for a street/strip/track car. (if the oil pump can't get the oil nothing else matters)

If you buy new rods you likely will need to rebalance the motor, the rod weight difference may be small but at 5- 6000prm it will start to matter. if your cam is only going to make power to 52-5800rpm like many do(even lots of big roller cams die off before 6000rpm) then you will go faster shifting before you hit that rpm. But if your cars rear is gear short (you were thinking 3.42) and your tires are small diameter too (some guys run 25.5" tall tires to lower there car and fill the wheel wells) then you may go through the traps in top gear at an RPM above your shift point. Or you can lift off at the top end.

Once you have the above addressed then Aluminum heads and a roller cam and rocker set up will give you that 100HP or more like 150HP especially if you dyno tune it. But the heads are in short supply at $2500-3000 ( maybe the Chinese Speedmasters are a good cheaper option here) and the cam/lifters and rockers are $1500+, don't buy Chinese rockers either, that is no place to cheap out Harlan Sharp or Crower only.

[highway star]

Eaton Posi and subframe connectors will be adequate. I ran thus with 4:10 gears and slicks at the 1/8th track with no breakage. Using oem 10 bolt 8.5 r&p. What about/plans for your stall converter?

[SoupMan]

Nas,

Good information. Not an engine builder but I understand the need. All this lines up with what I read in the Jim Hand book and some. I'm figuring my best bet is probably to buy a pre-assembled block and build from there. Any opinion on turbos?   I figure a small turbo would wind pretty quickly with a big displacement. Could be a fun build


Highway star,

My current stall is a 2800 stall and nothing really fancy. I'm under the impression you need to figure out your power, your cam and then picking the rear end gear + converter is just a matter of what you want from the car. Am I correct in assuming that?

[ryeguy2006a]

So as much as I'd like to tell you to get specific parts to get you that extra 100HP, I'll suggest something a little different. Given your current setup with the TH350 and 2.72 gears, I'm going to suggest that you buy a built 200r and go with a set of 3.55 gears. Your seat of the pants feel will be drastically different and you'll be able to feel that 500 hp way more. 2.72 gear is a highway gear, not a performance gear set. My guess is that if you make those changes, you won't be wanting more power. My LS1 360HP with 4.11 gears was a beast on the street.

If you are set on getting that 600 RWHP dyno sheet, it sounds like you are going to be needing a full engine rebuild with high end parts. Another thing that I didn't see an answer to was who tuned your car? If you tuned it yourself with one of the preset tunes, I'll be there's room on the table for a high end tuner that knows how to squeeze out more HP. I know a guy who does remote tuning if you are interested. Send me a PM.

Best, Ryan

[SoupMan]

Rye,

I think I've got my direction set. The 200R4 is something I was already looking at and it's well within my budget. As for the tuning, no it has not and there's lots of potential there. There is definitely room to improve performance from just tuning the EFI and the timing.

As of right now my list goes like this:
- Sort out my air. I know I get get cooler air in the manifold as well as remove the drop base. Currently running a 2" drop base with a 3" filter which I'm sure is restrictive
- Tuning (I'll PM you for details)
- Debating the hyperspark to complement my sniper EFI. It would provide more tunability
- Get in touch with my trans guy. He did a good job on my TH350. I believe he has a few 200R cores.
- Look at a locked diff and go to a 3.55 gear

I think that alone will get me to reach my objectives. If not, dish out the money and find a buyer for the current setup.

[ryeguy2006a]

That sounds like a great list SoupMan. What are your IAT's now with your current setup? a 3" filter is pretty decent size, but you can will likely benefit from cooler air. If they aren't too high, I'd just run what you have honestly.

I'll bet you see a decent gain from the combination of the spark control and a good tune. What's great about allowing Sniper to control timing is that youcan set the timing ramp to whatever the motor likes. With a vacuum distributor you always have compromises that you have to make somewhere in the part throttle range.

[SoupMan]

My IATs during the summer hover at 135 to 150. I'm seeing other guys with cars from the era see 115 to 125 with their snipers EFIs.

I'll start looking at the spark control before I get a tune. Currently the advance is set mechanically

[nas t eh]

I think an overdrive auto and better rear gear with posi is a great plan.

[Vroom_vroom]

what kind of compression are you running? your dyno numbers are pretty much dead on to what my 400 put down. if you have good compression id stick with some aluminum heads, roller cam and long tubes. after having the kauffmans i wouldn't go back to a iron head to save my life (dramatic but true) play around with the cc numbers as well on aftermarket heads if you need to get the compression up a touch more.

fwiw i have the drop base from ptfb when i put my car on the chassis dyno i pulled it off for a run just because. 15hp/13tq bump granted it was not running a filter at all but the drop base is known to be restrictive. i feel like blockers is the best one on the market and is custom built.

[chief poncho]

Looks like you already got some sound advice here.  I do think the key to getting another 100hp reliably out of your engine is to beef up the bottom end with forged components, aluminum heads and a bigger cam.  I think 500+hp is an easy target.  I wouldn't go with a turbo or supercharger, but it would make your 600hp goal a bit easier.  I think the real question you should ask yourself is how much is enough?  If you only have 2.73 gears now, going down to some 3.42s or so would really make the car feel a lot quicker.  Also an overdrive transmission would make it very liveable.  I think you could even get away with just adding a set of aluminum heads and a bigger cam to get the performance you want and if you limit the RPMs to 5500, you wouldn't have to worry about the bottom end.

[SoupMan]

Lots of very good advice. I've already starting looking at who around here could get me a 200-4R for reasonable price. My trans guy (TH350) hasn't answered yet so not sure he's still in the business. I'm in the Toronto, Ontario area.

Any advice on how big of a converter I should run with my setup?  Currently running 2800.

[DynoLee]

HP comes from the heads.  Those heads flow about 205cfm (just like virtually every other D-port Pontiac head with 2.11" valves) which is enough to make a bit over 400hp (with a streetable cam design and pump gas compression ratios).  At the least, you'll need professional porting done to the heads (at least 260cfm) to get to your "520hp" goal. 

I'd also go with a 3.0" exhaust.

[SoupMan]

Anybody I can send my intake and heads to port and port match?

I'm in the Toronto, Ontario area.

[DynoLee]

My first choice would be Dave Bischopp, at SD Performance   http://www.sdperformance.com/.  Dave is in British Columbia, but was hit hard with the recent floods and is not taking any new work at this time. 

There are other guys out there, but I've been a loyal customer to Dave since the 90's, and don't have any experience with the others.  Next choice is a set of D-port aluminum heads, but even those are taking 4+ months from time of order to delivery.  My first choice for those would be Kauffman Racing's KRE D-ports.  The KRE's give you the additional advantage of having a modern combustion chamber design, which will make a bit more power than similar cfm iron heads.

[5th T/A]

SoupMan,

A lot of good suggestions have been posted here. I agree with Ryan’s suggestion of changing the axel ratio and upgrade to a Positraction differential. This alone could make a day and night difference. I am not aware of a 3.55:1 ratio for a GM 10 bolt; you may have to choose between a 3.42:1 or a 3.73:1. You mentioned the turbo 350 is already built for high HP/torque, so you could add the 200-4R at a later date. Just make sure the transmission you install is built to withstand your ultimate power goal, or you end up paying more in the long run. If you do much highway driving you will want an overdrive transmission.

As nas t eh mentioned you may be going down a Rabbit hole with one thing leading to another. Stock Pontiac connecting rods being a weak point. Probably OK for 400 horsepower, pushing it past that is asking a lot. Are you planning on installing sub-frame connectors to reinforce the chassis? Drive shaft and yoke upgrades from 1310 to 1350 u-joints? Too wild of a cam will sacrifice street drivability and reduce vacuum, you may have to install a hydro-boost for your power brakes. I would install a high capacity road race oil pan to avoid oil starvation during hard acceleration and cornering.

FYI for comparison, last year I replaced the stock low performance 301 in my 1980 TA with a 461 built by Butler Performance. I purchased it from another TAC member who had it built but he never installed it.

It has the following parts; XX-481988 400CI block, Lunati roller lifters, Comp custom grind billet roller cam, Scorpion roller lifters, Canton Road Race oil pan, Melling 80 PSI oil pump, Powerbond/Dayco harmonic balancer, Edelbrock 87cc D-port heads, Lunati valve springs, Chromemoly pushrods, Edlebrock Performer RPM intake, Ram Air Restorations 2.5” exhaust manifolds, Ross forged piston’s, Eagle H beam forged rods, Eagle 4340 forged crank, FAST EZ-EFI 2.0, FAST dual sync distributor and many many more parts. Engine was built, blueprinted, balanced and dyno tested by Butler at 488.7 HP at 5,000 RPM and 580.0 foot pounds at 3900 RPM. This motor has a mild cam and runs without problems on 93 octane pump gas. I do not know if the heads were ported or not. These numbers are less than the numbers you were looking for but not that far off.

While crankshaft dyno numbers are nice I think chassis RWHP is more valuable and will give you a better idea what your car will do. My car has a stock 1974 SD exhaust system and only a 2.41:1 axel ratio. I don’t plan to race it. Running the stock P225 70R -15 tires I have terrible traction problems. But still manage to get 4.4 second 0- 60 times with my performance computer (for what it’s worth).

Although I enjoy the power and torque, my car is used for cruising. For me it was important to have a normally aspirated Pontiac engine in my car. But if I wanted a 600 horsepower street monster with the best bang for the buck I would follow ryeguy2006a (Ryan) and do a super charged LS engine. The power, reliability, drivability and cost is hard to beat.

One last suggestion. You can certainly get a lot of power out of a Pontiac if you are willing to invest the time and money. I would suggest purchasing the book Max-Performance Pontiac V-8's, written by Rocky Rotella, ISBN 978-1-61325-474-5. It's filled with lots of valuable information.

[SoupMan]

5th,

Thanks for the added info. I've already ordered my ignition stuff. (hyper spark, controller). The tuning will be a big part of getting HP.  I have connectors in the works.

It's pretty clear to me I'm not doing anything crazy to the motor and if I do I will limit the RPMs (I barely ever see it hit 5k anyway). Next year if what I do this year isn't enough.

I've looked at the 200-4r. By the time I get something worth talking about I'll be to 2-3k in. I've pretty much decided on getting a known working 4L80e. Get a Quick4 and go from there. It's about 2-3k but it's a bullet proof trans.

[ryeguy2006a]

4L80e is a great trans, so you won't be disappointed there. However, one thing that may be a consideration is to look at the Terminator X Max ECU. You can control the 4L80e and you would have the option to upgrade in the future. If you are going to be spending the money to get a stand alone controller anyway, it may be worth it to sell the sniper and upgrade to the X Max. It would be more seamless to have the same ECU controlling the engine and transmission.

[SoupMan]

Rye,

I've looked at that but the only thing is it's rated for 800+. Holley says you can get away with 700 to 800 but anything less than 700 may not work. I'm assuming it has to do with the injector size or something along those lines. The Terminator X would be a lot better for me since there are inputs and outputs it supports the Sniper EFI doesn't.

[ryeguy2006a]

https://www.holley.com/products/fuel_systems/fuel_injection/terminator_x/terminator_x_and_x_max_stealth_4150/terminator_x_max_stealth_4150/parts/550-1012

This is the one that I would be looking at if I were you. The added I/O support is really nice for controlling fans and other accessories. This above kit is good for up to 650 HP so it should work perfectly for your car with a little room to grow if you wanted.

[SoupMan]

I'm in for that price. I'll see if I can offload the Sniper EFI. Although, I need a little time to get there.

[ryeguy2006a]

The really cool thing is that with the Terminator X, you won't be "stuck" with just the carb replacement throttle body. You could always get a new harness if you wanted to convert to MPFI, or if you went LS.

I've always wanted to add a cam/crank sensor to a Pontiac motor and add sequential port EFI with a TB.