Thread: My latest custom project- 4T80E swap in our 1997 Grand Prix UPDATE- Its on the road!

found out that PI does 4t80e converters

And guess who worked with them to lay out a custom 4T80E / 3800 S2 converter option.

TCC controls are of no concern on the 4T80E. There is no TCC pressure switch in a 4L60E or 4L80E either, pwm will work fine. There is a switch option to use or not use the TCC switch in the pcm code. Shift solenoid state gets reversed. After that it is simply plugging in new iss and vss values to get the ratios correct. Getting the trans tuned with a 3800 pcm is a non issue for this project or I wouldn't have done it.

Originally Posted by Trannyman95

And guess who worked with them to lay out a custom 4T80E / 3800 S2 converter option.

TCC controls are of no concern on the 4T80E. There is no TCC pressure switch in a 4L60E or 4L80E either, pwm will work fine. There is a switch option to use or not use the TCC switch in the pcm code. Shift solenoid state gets reversed. After that it is simply plugging in new iss and vss values to get the ratios correct. Getting the trans tuned with a 3800 pcm is a non issue for this project or I wouldn't have done it.

What about this trans working with the t42 controller ? Seems most tables you mentioned are in out tunes as well. (Ls4)

Thanks Brian! Its been a long time coming just not much time to work on it. Hope all is going well and your GTP is still running strong.

In regards to an LS4 application - the big obstacle here is the starter. The LS4 already his a decent mount mount arrangement so some of that could be incorporated to this and in fact I wanted to use the front lower LS4 engine mount for this project as a base to rebuild a better one since the factory mounts are pretty weak and almost every one that comes in is torn in half. The holes were already in the frame (on the bottom side of this 97 frame) and after drilled the LS4 mount fit perfectly so I was hopeful but turned out the AC compressor and bracket was in the way so I started from scratch.

What are the odds of us "home mechanics" being able to do this project successfully?

Its been slow progress moving forward on this but I have done quite a bit the past month on the car. The turbo piping is almost finished up and a rear manifold is done to match the fitment of the new trans. I am using Aeromotive 3800 S2 fuel rails and had to make new brackets to fit the Fbody intake manifold so those are finished up, just need to plumb it. Hopefully in the next few weeks I will have this ready to fire. I will try to get some new pics posted up soon.

Sweet!!!

Finally got to start the engine yesterday. Lots of little things to finish this up that has been what seems like countless hours! Should be on the road in a few days. Rough tune is done so far just going over everything. Intercooler not installed yet but the engine will get several hundred miles put on it before any aggressive driving anyways since it is all fresh.

Below is a finish pic underhood and a few others. A few odds and ends left that will get tidy'd up after we put some miles on it. I have tons of pictures of everything just need to sort through it.


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Looks sweet.

Best looking turbo fbody intake setup I have seen...so clean!

More pics-

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that tranny is a monster. hard to believe it fits.

Just took car for first drive around the block. Trans feels great thankfully! 160K miles on it and good solid shifts. Lots of tuning to do on engine but at least its on the road. Now just need to finish tune and go try to break it

It's alive!!!

How's this coming?

hey dave you stil planning on switching to the later 80e IMS?

I am due for an update on the car. So far so good with the trans. I ran into a few minor things along the way that needed tweaked a bit but so far the trans has been working well. The temporary T70 on the car (TE60 being rebuilt due to turbine seal leaking) at 17 psi is a beast though the 2-3 shift at WOT is not the strongest so I have to play with that a bit more but there is more room in the tune to bump shift psi up a bit. Torque management is also completely turned off from some prior trial and error effort to sort out some odd behavior which turned out to be gear ratio vs gear related as the pcm always say 2nd gear slipping so would pull crazy amounts of timing out. A big downfall with this trans in stock form and in a vehicle is the ability to do anything for 3rd gear. The 3rd accumulator is in the valve body area in the side cover so you can't mess with it once in the car. If running max psi on the 2-3 shift isn't good enough then some work will need to be done to the trans before installing.

James- no plans for newer trans with IMS at this point at least on our car. It would definitely free up some room for the exhaust and you wouldn't have to build a custom rear manifold like I did!

Hoping to make it to the track soon with some numbers. The 245 Falkens on the front don't agree with this setup at all so waiting on MTs to come in. Currently at 50mph and not even going WOT it will haze the tires. Pulls like mad once you get through that and into 3rd gear though!

More food for thought- I am using a late 90s N* maf sensor in a 97-98 style L67 throttle body and NO translator- even with this turbo at 17 psi I am only hitting 11,100hz so there is a bit of room left in it. Makes for a cheap upgrade with no modifications other than tuning. I will report back once I have some more time with the car and hit the track. It has about 1800 miles on it now.