Author Topic: LT4?  (Read 767 times)

shwstpr88

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LT4?
« on: December 18, 2017, 01:02:27 AM »
So I am wondering..... in my 81 trans am if I put this in there:

http://www.chevrolet.com/performance/crate-engines/lt4-wet-sump

Any issues with fit/issues in general? It would be nice to have a modern powerplant, reliable, and able to have an overdrive tranny.

skisix38off

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Re: LT4?
« Reply #1 on: December 18, 2017, 07:30:15 AM »
The LT4 is still based upon the LS architecture and there have been many threads posted about the swap to LS powerplants.

stan65

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Re: LT4?
« Reply #2 on: December 18, 2017, 10:32:32 AM »
What would you like to know? I am in the process of doing the same thing to my 71.

shwstpr88

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Re: LT4?
« Reply #3 on: December 18, 2017, 01:16:34 PM »
I'm at total stage one so I know nothing about the process yet in my current 79 I have a Pontiac 400 with a scooper Hood. So I guess I have a million questions haha. 1 if I were to get a brand new lt4 supercharged with the 8-speed transmission are there any fit issues? Where would you get motor mounts? How do you handle the hood with the scoop? I guess the main issues are mainly fit to get started but also curious about modern air conditioning and that upgrade process and what type of gauges do you need to change to or can you run your factory ones? I'll be thinking of a million more but if anybody has any threads I would love to tag along and start reading.

FormTA

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Re: LT4?
« Reply #4 on: December 18, 2017, 02:17:12 PM »
There are a few LS swap threads on this site. I like others have used dirty dingo motor mounts but there a bunch of others. My LS swap is a low buck one, there are LS3 and others on here as well.
79 Trans am 301 (work in progress) LS swap n progress
79 Formula 301 (Work in progress)
67 RS Camaro (Work in progress)
See the recurring theme???

Re: LT4?
« Reply #4 on: December 18, 2017, 02:17:12 PM »

Old Chicken

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Re: LT4?
« Reply #5 on: December 18, 2017, 08:03:49 PM »
You're going to have to chop up your tunnel big time to make that eight speed fit. The DI Lt4 does have some trouble with valve coking, the 8 speed doesn't have the best reputation either.  They do make good power though.
« Last Edit: December 18, 2017, 08:08:20 PM by Old Chicken »

shwstpr88

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Re: LT4?
« Reply #6 on: December 19, 2017, 02:19:05 AM »
Any good tranny options out there that do not require surgery?

Also with an LS swap do you need updated guages or do our old guages still fly?

FormTA

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Re: LT4?
« Reply #7 on: December 19, 2017, 05:44:46 AM »
I bought converters to run my stock ones. Most others run after market ones. Speedhut seem too have a good rep.
79 Trans am 301 (work in progress) LS swap n progress
79 Formula 301 (Work in progress)
67 RS Camaro (Work in progress)
See the recurring theme???

ryeguy2006a

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Re: LT4?
« Reply #8 on: December 19, 2017, 07:16:30 AM »
Make sure that when you buy the mounts that you get them for the Gen5 motor, as the mounts are very different from the Gen 3 and 4 LS motors. Also, I believe that the exhaust header flange is different as well. You may want to reach out to Holley to see what they have available for mounts and headers.

As for the transmission options, I haven't been able to determine 100% if the LS transmissions will work or not. I know that the top center bellhousing bolt on the Gen5 motors are offset to allow for the DI pump, but I believe they will bolt up if that bolt isn't used. Meaning that the T56/TR6060 will bolt up and function. Also, the crank uses an 8 bolt flywheel as opposed to most LS motors use a 6 bolt.

I have been keeping an eye out for a '14+ 5.3 motor to see what it would take to get it going.

Good luck and keep us posted.


1976 Trans Am LS1, 6 speed, C5 12.8" Brakes, LS1 rear 12" brakes, 17" Aluminum Rims, and much more...SOLD
My Build: http://transamcountry.com/community/index.php?topic=24465.0

New project: 1968 Camaro with 6?.?0?  5.3 w/ Z06 cam/T56
http://transamcountry.com/community/index.php?topic=74591.0

stan65

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Re: LT4?
« Reply #9 on: December 19, 2017, 07:37:53 AM »
This site will give you an idea of the changes in the motor mount bosses LS to LT

http://www.chevyhardcore.com/news/lt-series-swap-guide-stepping-up-to-gms-latest-small-block/

you will have to scroll down, there is an overlay of the 2 in cad.
I am going to make my own as they look simple to me. I already had the LS mount kit. I installed a mockup LS with my trans and located the trans crossmember. Now that that is done, I will remove the LS and bolt the LT4 to the trans and I have my front to rear location nailed as per detroit speeds specs.

As far as fit, I am using a Detroit speed subframe. The stock LT4 pan will hang to low so I opted for the Holley pan. This will open a new can of worms for the oil cooler.

The stock LT4 manifold appear like they may fit. Will have to check the steering linkage. (subframe not under car yet) Also do not know if they will fit with a stock subframe as the shape is diiferent where the lower control arm attaches at the rear.

Holley helped with Mark Stielows "Gunner" build
http://www.superchevy.com/how-to/engines-drivetrain/1708-mark-stielow-lt4-engine-swap-into-a-1969-camaro/

I wouldn't recommend putting the power steering pump on the blower belt as there have been pump issues with the amount of tension on the belt.

I used a Drive Junky front accessory drive on mine. NOT CHEAP or Fast to ship, but a very nice setup.

As far as mounts, I am going to make my own.

On the transmission I went with a Tremec TKO600 5 speed from american powertrain. I was assured there will be no trans tunnel issues.


Here are a site I will throw out for you to read. it has links to and iformation about the LT4 swap
http://automobileman.com/wp/

good luck!

Old Chicken

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Re: LT4?
« Reply #10 on: December 19, 2017, 07:43:10 AM »
You can pretty much run anything for a manual or 4l65e for the overdrive auto.  As for gauges, there are companies out there selling adapters so you can run your OEM oil pressure and temp sensors. That way you keep all your original wiring and gauges if you like. That's what I'm doing on my swap with an LS1. Another good resource is the high tech retrofit section at nastyZ28.com.

Re: LT4?
« Reply #10 on: December 19, 2017, 07:43:10 AM »
You can help support TAC!