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

Subbed!

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Dave we would all love you forever if you made us a kit to do this once you finish. Me and several of my pals would scoop it up right away.

.........subbed as well for awesomeness

Thanks guys. Not much to update the past week or so on this. Starting on wiring- this is a 97 car and due to the relocation of several things I am pretty much rebuilding an entire harness to work with all of this. That is not something necessary for the conversion, just something I am doing to best fit the engine layout.

Transmission shift linkage bracket and lever were made to work with the factory cable and stay clear of the turbo so that is covered.

Axles have been sorted out and is a simple drop-in solution. There were really only 2 main axles used in the vehicles that had the 4T80E transmissions and these vehicles all used the same axle both left and right side. A main stream Caddy/Aurora/Bonneville GXP axle length was a great fit on the drivers side. The Eldorado and a few other models used a shorter axle which turned out to fit great on the passenger side. The outer end of these axles is the same as the Wbody so nothing needed to be done with them, simple solution.

The throttle body and battery arrangement has been finalized and I can retain keeping the battery in the front, just turned 90 degrees from stock location to give a little more room for the inlet tube to the throttle- which will now be located in front of the fuse and relay box due to this being an Fbody intake. This is a 99+ style Fbody upper intake which used a drive by wire throttle body, though I am using an L67 throttle body which works with stock throttle cables and also will work as the stock cable is very long and wrapped around the strut tower so gives plenty of length to move to the other side. I found that moving the fuse and relay box backwards about an inch opened up a bit or room and clearance for the throttle body to fit here, lots of chewing on ideas and relocation but turned out to be a very easy fix.

After wiring is finished up I need to build a rear manifold/header and fab up the new crossover pipe to feed the turbo. Since I have the throttle body on the passenger side it opens up a lot of options for a front mount intercooler. A Tru-Cool maxi cooler transmission cooler will be fitted just above the intercooler which is what I have been using for the LS4 V8 turbo cars and works very well.

i knew it!
sweet then i have everything i need! i have 1 set of early and 1 later 80e, took em all home with me after finding the collapsed lengths different

you dont think there's a third length out there do ya? we really wanna tuck the rear inward more since we dont need to turn but we do need Wiiiide tires lol

i wanna see more pics up 'er skirt, pleeeeaaasssseeeeeeeeeeee

Coming along nicely! Keep up the good work!

update?

subbed for boss sauce :s

Engine wiring is now finished just need to go over harness with loom. New battery tray came in so that is mounted and I am working on building the throttle body adapter and then on to building a new rear manifold and turbo piping.

Sweeeet! How hard is the PCM programming going to be? What is going to have to change? Also, do you know if there will be a kit/write up for this. I want to do this for my turbo build :P

im still confued about moving everything foward an inch? and how that affects axles and everything else?

The pcm tuning will be a bit of work to first get everything ironed out but I already have support to make the changes needed for the trans. The 4T80E is actually similar to a 4T40E electrically so it was just a matter of verifying several things. Until it starts and drives I won't know for sure as it is going to take a bit of tweaking to work correctly just as I ran through building a RWD L67 file for my 86 Cutlass.

The engine moving forward an inch isn't hurting anything and the axles are very straight in the car. Something else to keep in mind- when guys lower these cars they often run a shorter upper dogbone to pull the engine/trans forward to put some angle back into the axle to eliminate a high throttle vibration. This isn't all that far different and the trans is larger anyways so part of that is offset. The back of the transmission is huge compared to a 4T65E so there is really no choice since you cannot go any farther backwards with it. If it turns into an issue then new controls arms will have to be built to move the ball joint forward the difference but I don't see any issues at this stage.

Originally Posted by darkhorizon

Considering that required zero tweaking, Im afraid you are going to have problems with the 80e controls.

Bonus is, if you cant get the PWM stuff working, you can just leave it on full pressure all the time.. unplugged...

Why on earth would you run full pressure all the time? I could see at the track but anytime else that would be horrible to drive at max pressure

Originally Posted by darkhorizon

Considering that required zero tweaking, Im afraid you are going to have problems with the 80e controls.

Bonus is, if you cant get the PWM stuff working, you can just leave it on full pressure all the time.. unplugged...

zero tweeking? even i had to do some finagling on both the tune/wiring sides to control the 700r4 for tcc lockup and as my only vss feed
i really didnt wanna do a manual switch for the tcc.
80e controls arent a major problem especially if he found the trans value that switches the shift solenoid logic.
the PWM/pcs havent had a problem at all even at the different frequency, its still limiting current and thats tunable, stock values on the low end are actually a bit harsh with the 80e
ive got several 4t80e pcms that ive wanted to read fer years but never was able to

found out that PI does 4t80e converters

Awesome. Well I have a car that is going need a trans, so if you ever want a 4t80 04+ Guinea pig... Im here

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)