Jacob Cote

So here is the deal i bought a 2005 sts for 1000$ as a no start with the intention of flipping it. Turns out it just needed a new battery and ive fallen in love with the car. Its a northstar 4.6L RWD car with a 5l40/5l45e transmission and well i want more out of the car. At first i thought buy a used blower from the 4.4L northstar and slap it on but ive heard the 4.6L is at max capacity for power hence why the 4.4L comes with a forged crank. So now im looking into an LS based swap and i have a GEN 3 5.3L LM7 laying around but also thinking LS3 with a 6l80 cause STS V came with a 6l80 so i know they fit in the transmission tunnel. So here are my questions i know the STS and CTS are on the same platform so im wondering can i swap CTS V engine mounts and brackets. Does the transmission crossmember from the CTS V fit the STS. Do CTS V manifolds work? If all this works can i get the stock moduals to work in the car with the engine swap i don't want to lose features. Note if any moduals need reprogramming i am an apprentice at a GM dealer so i can do it there. And my STS has a G80 LSD rear end ive heard first gen CTS V rear ends are glass and ive seen Cooper from the Cletus McFarland channel put a ford rear end in his CTS V wondering if it would work in the STS. Thanks for reading hopeing for good news.

MN_V

iTrader: (5)

This is a bad idea and something you will look back on and realize it was a really poor decision to do if you move forward with it. If you like the STS that much, sell this one for a significant profit from your purchase price, and buy an STS-V. It's better and cheaper than doing this swap into your STS and is a complete package with the suspension, brake, and aero upgrades.

BudRacing

iTrader: (3)

This is very sound advice. If no STS-V existed, then I could understand the desire. However, building your own won't be cheaper or better than the real one that's in a depreciated and obtainable state. Nor would it have the resale value of the real thing either.

MN_V

iTrader: (5)

Yeah imagine trying to sell a base model STS with a truck engine swap with who knows how many adapters and wire harness modifications. You'd have to nearly give it away. You can pickup an STS-V for under $10k nowadays. 469hp and plenty of torque to get the big girl moving along with all the other additions. If you like your STS you'd like an STS-V even more. Better yet... get a V1....

AAIIIC

iTrader: (19)

The V-6 CTS doesn't use the same engine crossmember as the CTS-V, and I doubt either CTS crossmember is the same as an STS crossmember. I don't see any reason to think you could use CTS-V engine mounts to put an LS into an STS.

Only one way to find out - buy one and try it.

Find someone who has done an LS swap into an STS and ask them. No way to know otherwise.

What modules are you referring to? There are a bunch of them throughout the car. You could most likely get everything to work, but that's going to come down to you doing all the homework to figure out what modules interface with each other and what you would have to do to make them "talk to" an LS ECM/PCM, TAC module, etc etc.

You need to read more about the CTS-V rear ends. As for whether an 8.8" swap would work in your STS, only one way to find out.


To sum all of that up, I agree with what the others have already said.

MN_V

iTrader: (5)

RIP OhhPee