3800 and 5 speed into a 96 GP?

[GranPrix]

I have a buick park avenue with a 3800 supercharged motor, and a manual 5 speed out of a 1990 grand prix ste. I am looking at a 96 GP coupe with a blown motor for sale for $400… could I put the 5 speed from the STE into it and mate it up with the L67 motor? Are the axles the same length and everything? I know I would need the ECM from the park ave and everything but as far as the transmission goes… is it plug and play going onto the subframe? 

[55trucker]

Mechanically speaking.....sure, is that L67 a series I or series II?, they were both available in the Park Avenue depending on year...

also I take it that the trans is the Getrag 282 as that was the trans used behind the 3.1 LHO engine in 1990......

the trans will bolt up to the 3800 with no issue, you'll need no less than a Spec 1 clutch to hold up to the torque of the L67 (assuming you don't beat on it) otherwise a Spec II would be what is needed.

You'll want engine mounts from a Regal or even the Monte fitted with either the L26 or L36 or the L67 engine. The trans mount is a basic manual trans mount.

The axle shafts for manual are the same piece both sides, what is not readily available anymore is the intermediate shaft used on the right side of the drivetrain before the axle shaft.

For the rad my suggestion is to pick up the 1 1/4" core rad from a 98 Monte Carlo fitted with the 3.8 engine, pull the entire intake snorkel assembly from one sitting in a salvage yard as well.

You'll want a wiring harness from a 1.5 Monte Carlo as well with the 3.8, the less pinning you have to do will make your headaches smaller.

The exhaust is straightforward, you want the downpipe assembly from the Monte as well, the Park is a different platform, expect the downpipe curves to be off angle unless you want to go the route of custom fabbing the downpipe. The majority of the exhaust will need to be enlarged, the tiny 2" dia piping for the 3.1 engine is too small for the blown 3.8 to let it breathe properly.

The PCM will need a tune put across it (Tuner Pro), not for performance sake but to eliminate all of the functions the PCM looks after in an auto trans environment. I take it that you intend on keeping the OB2 in the car.

I do believe that Bake82 has an '88 Cutlass with an L67 sitting in it, he would be able to offer more indepth info on what was necessary in this sort of transplant.

 

 

 

 

Edited December 16, 2023 by 55trucker

[Bake82]

Assumptions: 

L67 from Park Avenue is a Series 2, if so, you will need the accesorry drive, exhaust manifolds/x-over, motor mounts, and possibly the oil pan and oil filter adapter from a w-body L67 car. 

55Trucker covered most of the L67 swap stuff, with the exception of the heater core hoses and power steering lines should be from the 98-99 monte carlo Z34/Lumina LTZ with the 3.8NA.

 

For the manual swap.  

I have a getrag 282 behind a L67.

 

Trans bolts up

Need a flywheel from a 98-02 3.8 Camaro shaved down to to a total of 0.82-0.84 thickness(Find FieroRog on facebook in the fiero groups and he'll sell you one for $300ish).  

I would recommend a Spec Stage 2+ for a stock motor or a 3+ for a modded motoer

Axles

- Driver's side use a stock axle from the 1990 Grand Prix

- Passenger Axle - hits the oil filter adapter in stock form.  You have 2 options- make a custom oil filter adapter block(have to be thin) and use a oil filter relocation kit.  OR What I have done is use the original Grand Prix oil filter adapter, and had a custom axle made.  I removed the intermediate half shaft,  got another driver's side axle, and used the inner tulip, and the outer axle stub going into the wheel bearing, and then found a 03-05 honda accord 4cyl automatic passenger side axle and used the inner shaft.  Put the grand prix outers with the accord shaft.    It's been like this for 15,000+miles, behind 300whp motor with no issues.   

 

There is also the interior side of the 96 grand prix you need to take into consideration for the 5 speed swap.  You'll need to find a way to mount the clutch pedal as they are different between the 1990 and the 96.