Thread: 4T60-e to 4T65-e in 97 GP GT

It will be quite a bit of work to do the swap but it can be done. You will need a complete different engine harness and pcm to work with the 4T65E. There will be custom tuning involved likely as well as possible wiring modifications to the car.

How much power do you plan to add? I used to build a lot of these transmissions and they can be built to handle more power than stock no problem, they just dont work as nice as the 4T65E since you cant tune the line pressure as it is controlled by a vacuum modulator.

LOL no offense but i dont see a Grand Prix GT(205HP)stock, gettin much faster than a Grand Prix GTP(240HP)stock.The reason being that they are way different in engines and trannys.I got 2 GTP's both stock and they are fast and have not found a GT,or even a Mustang GT for that matter, to even run close to me or any other GTP's.the L67 is one tough,strong,reliable and undefiable engine up against the L32 in my book. which does not have the components that are really racing material built for the drive hard and severe torque that the L67 with the m90 eaton blower puts out.so goodluck man.that is my opinion and i am stickin to it lol.

In response to the last post,

I understand your point. I used to own a GTP myself, but sadly it was totaled by a lady who rear ended me at 45 MPH. The L-67 is a very stout engine but you have to understand that the Gen 3 Eaton M-90 bolted to the top of an L-67 actually holds it back a little bit because of the fact that it is belt driven. Whereas a turbocharger on a L-36 can more efficiently provide boost without robbing some of the horsepower that that boost provides. There's ups and downs to both sides. The GTP is probably the best option as far as reliability because of the simplicity of the supercharger and it's definately cheaper to modify. On the other hand, there's GP GT's that are turbocharged running 9 seconds in a 1/4 at 150 MPH, but all that power is really gonna cost some money. The transmissions for these two cars really are not all that different. If I'm not mistaken, the only difference between the 4T65-e and the 4T65-HD is an HD differential, 2.93 gears( vs 3.29 gears), and an HD passenger side axle. I of course have the 4T60-e transmission, which was phased out after 97. All I really want to do is see if I can beef up that tranny should I decide to run a turbo or other power adders so that I dont end up going through transmissions.