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2006 STS V8
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45 Posts
Discussion Starter #1
1st off, I know this is likely going to go "against the grain" for most here, but don't care if people don't agree with my choices, don't think a rumbly engine belongs in a Cadillac, or are just going to tell me it's easier to just sell my car and buy a V. It's not intended as an insult, or attack on other's opinions..mine just happen to differ, and my reasons for buying my STS probably differ from yours ;) I don't want a CTS or CTS-V, I bought my STS because it's a larger and more comfortable car. There's still a large delta between the value of my STS and a STS-V, and that would still leave me with a relatively lightly supported platform with the Northstar. This is far from my first engine swap, and I have experience going from old school carb to modern OHC EFI set ups. Soo....

Read over the thread from the CTS forum from a few years back where a guy replaced the stock V6 with a SBC/700R4 combo - Engine Swap - small block Chevy into '06 CTS , and it got me thinking about my own car again. I have a 2006 STS V8 base, with 180K on the clock, and a wish for a bit more smiles per gallon, and I've never really been happy with the way the transmission in this car shifts, auto or manual mode. I also happen to have a hot SBC attached to a fresh 4L80E sitting in the garage begging to get used in something.

I know this isn't going to be a plug and play operation...the fun ones never are. I know I'm likely going to lose some level of electronic/accessory function doing this, and I'm OK with that. I don't care about things like ABS or traction control still functioning. I can work around gauges if need be, but assuming the stuff in the STS is similar to the CTS, it sounds like that would be a relatively simple thing to deal with as well.

My big things are still wanting to maintain power windows/locks/seats, seat heaters, and climate control. If I were to lose the seat memory functions, that's not the end of the world...I'm the only one who drives this car anyways. My gut feeling is that none of this kind of stuff is directly tied to the engine ECU, and likely all handled by the BCM? I'm thinking worst case scenario, I can always run a piggy back ECU to leave the factory ECU in place to handle these functions, with the piggy back handling the engine operations? Can I just unplug the engine harness from the ECU to test to see what works and what doesn't? I know that sounds like a simple thing, I'm just not sure if it will cause other oddball things to happen.
 

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2006 STS V8 AWD, '95 Ford Ranger
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29,055 Posts
All communication in the car is by computer bus; CAN BUS. This is a handshaking system that requires not just message sending but also verification. Even things like low voltage can produce theft system lockouts, starting system freezes, and dead instrument panels. If you start out on this project I suspect it will rapidly evolve into a career. Everything is tied together. A suspension problem can result in fuel cutoff at 82MPH. Stability and traction control problems can give unpredictable throttle cuts and braking. I wish you the best of luck and keep us informed.
 

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2006 STS V8 AWD, '95 Ford Ranger
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29,055 Posts
I have 60 years experience in military and industrial electronics and have put a 425HP 396 in the back seat of a Corvair and I don't think I would live long enough to work out all the kinks in your endeavor.
 

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2008 STS Northstar RWD, 2000 Trans Am WS6 6 spd, 1968 LeMans convertible 6.6
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256 Posts
^^^ I agree with you Blinky, but as you know the only electronics needed to put that 396 into the Corvair was the wire to the distributor, and maybe the choke.
 

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2005 STS V-8 1SF Magneride HUD/ACC, 2008 Escalade ESV 1SZ Y91 Luxury Edition
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1,471 Posts
Well the LS6 has been swapped into just about everything - foreign and domestic- so it can't be that tough. Saw a Saturn Sky with an LS swap. That had to rock in a little car like that. Just looked at an 02 Trans Am that had its LS1 swapped for a built 6 that dynoed at 500hp. Go for it!
 
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