My primary area of expertise is with Duramax engines and Allison Transmissions, so please forgive my newb questions.
A friend of mine has a 2004 Grand Prix GT. He was considering getting rid of it, but if he could make it more fun to drive (IE: more power ), he'd keep it for a long time, like me.
I read over the top swap thread, and I'd rather not do that. I'd rather have the lower static compression of the L32 and maybe run a touch more boost than have the higher static compression +boost of a top-swapped motor. Do the GT & GTP use the same PCM, with only the programming being different? IF we go this route, my plan would be to pick up a motor and transmission from a GTP and drop them in, along with the GTP's PCM (Assuming it's the same), unless EFILive releases support for that PCM and I can get a GTP's tune. What PCM does the 04+ GT & GTP use? It looks like it MIGHT be an Atlas PCM (it appears to have a 56-pin C1, 73-pin C2 and 56-pin C3, which both the Atlas PCM and E40 ECM have, although I know it's not an E40)
The other though I had was a GXP's 5300 LS4. Near as I can tell, the LS4 weighs 478#, but I can't find any weight info on the 3800. Since the 3800 has an iron block and the LS4 has an aluminum block, I'm thinking that the two are likely similar in weight. I'm going to "study" the electronics on the GT/GTP/GXP's, and maybe even see if I can find an intact GXP to look under the hood, but on the mechanical side, does anyone know if the motor mounts differ between the two on the cradle side? They're probably different on the block side, but will the LS4's mounts bolt into the GT's cradle? I read the one thread I found related to a LS4 swap, but there wasn't any useful technical info. The advantage to swapping in a LS4 with the E40 ECM & T42 TCM is I can tune them with EFILive. If the LS4 will physically fit without TONS if work, I might be more inclined to go that route if I find the electronics won't be more trouble than swapping an 04 Mustang GT PCM into my 95 Cougar (which was a lot of work, but it works, save a few DTC's I need to iron out).
Edit: On quick look at the GXP's computer data lines circuits, it appears that, like the 06/07 LBZ Duramax powered trucks, the ONLY thing GMLAN is doing in the GXP is ECM/TCM/DLC comms, so if we went that route, I'd need to add GMLAN to the DLC for diagnostics only. The ONLY difference between the Computer Data Line schematics for the 04 GT & 06 GXP is the addition of the GMLAN between the ECM, TCM & DLC.