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CTS 2.8 to 3.6 swap (it's happening)

29K views 48 replies 16 participants last post by  AAIIIC 
#1 · (Edited by Moderator)
Hey everyone!

Have a 2007 CTS 2.8 with an engine about to go. Planning to do a swap to a 3.6 - does anyone have experience with this?

Should it just be a straight reflash of the ECM? Any trouble with security/vehicle acceptance?

Also, any other mechanical issues to be aware of?

Thanks for your help!
 
#7 ·
The 3.6 has a lot more torque across a broader band, so if you have a 3.6 laying around then I say go for it. The only difference between the 2.8 and the 3.6 is the cylinder size and related hardware. It should pretty much be plug and play. Heck if you resleeve the cylinders and get the internals from a 3.6 you can turn a 2.8 into a 3.6. Hmm how about getting the LP9 turbo 2.8 out of a saab 9-3, or saab 9-5 (2010 -2012) 280 hp, 270 tq. might be fun to look into. Here is the wiki on the engine. http://en.wikipedia.org/wiki/General_Motors_High_Feature_engine#LP9_Turbo
 
#8 ·
I've pondered this question about 2.8 to 3.6. Is the actual tuning different? Or will the ecm sense added airflow and compensate? If not do you need an ecm from a 3.6 or have one programmed? The programming seems to be based on the cars vin. If you program the vin of a different car or use an ecm from a salvage car will the bcm conflict(are the bcms programmed to the vin?)? Like some gm radios have to be programmed to the vin or they say theft lock. Can a aftermarket tuner do this?

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I even looked up the engine wiring harness and its the same.http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=375605&ukey_make=1023&ukey_model=14463&modelYear=2007&ukey_category=19592&ukey_trimLevel=14343 http://parts.nalleygmc.com/showAssembly.aspx?ukey_assembly=375623&ukey_make=1023&ukey_model=14463&modelYear=2007&ukey_category=19592&ukey_trimLevel=14343
 
#10 ·
-=chuckles=-Okay okay, this is pretty funny. If you are very worried you can go to dealership after the install and have them reprogram the ecm for a hundred or two. Yes, you can reprogram the gear ration from the rear as well so the speedometer is correct. I am not sure that it would need it for the engine size since the ecm is smart enough to relearn the air flow, power output, knock and timing. Think of it like this: If the car was running at a high altitude with less air it would adjust right? But if you are worried just get a dealership to reprogram it.
 
#12 ·
Hi again!
Thanks for the responses and interest guys!

Aurora and Curt, the motor is toast, it's getting pulled. So it's either another 2.8 or the 3.6, why not right?

Kael, those Saabs sound awesome. But they're FWD or AWD, possible difference with where accessories and such are mounted...

As for the ECM and related issues, we have a programmer.
So I'm guessing all the issues everyone is assuming there will be is with the ECM

Well! We've found a 3.6 out of a 2009 CTS AWD (yes, it's the LY7)
Does anyone know why the AWD LY7 would be under a different category than the RWD?

Thanks again!
 
#15 ·
Lol, I asked for help... and genuinely could've used some tips...
But the thread went dead even :/

Anyways, I was gonna post some simple pics, but couldn't on my phone

As for the video... What kinda video were you looking for?
I'm avoiding pushing it too hard as I just put in a new clutch
 
#17 ·
Man great job. I think the reason you didn't get a lot of responses was you're in pretty uncharted territory here. So back to the swap, was it just plug and play or did you have to swap ECU's or program it differently? Any parts on the engine have to be swapped out?
When not if I need a motor down the road this seems like the logical swap for me. New clutch you say? Which one did you go with? I put in a luk which was stamped valeo same as the original and OE flywheel.
 
#18 ·
I think the reason you didn't get a lot of responses was you're in pretty uncharted territory here.
Bingo! You can't expect to get many answers when nobody on the forum has done what you want to do. Presumably you've learned the answers to the questions you were trying to get answered at the beginning of this thread, so share your hard-earned knowledge so that others can benefit.
 
#19 ·
Exactemundo, Personally with the readily available 3.6's out there id have kept the other car for spares or part it out and bought a ready to roll car, if your involved in a crash and things dont match up ie vin/engine codes etc, the blame will be all at your door.
Congrats on the swap though :)
 
#26 ·
...if you['re] involved in a crash and things dont match up ie vin/engine codes etc, the blame will be all at your door.
:hmm: The blame for what?

But you've gotta understand why I felt a little bitter. I see countless threads for other people end up nowhere on here...
I participate in another forum for my motorcycle which everyone chimes in even if it's just to say they don't know, to point someone in another direction, or give wild suggestions for possibilities! Which often does create ideas that work!
As matt0305 pointed out, it's mostly just the demographic of CTS owners. When these cars were new, the typical CTS buyer was not someone buying a car to "mod", they were just buying a sporty entry-level luxury sedan. And now that the cars are older and more affordable, again you're not seeing very many enthusiast buyers because there's very, very little aftermarket support.

The ECU was not reprogrammed. I will be doing a baseline test, comparing tables in the 2.8 vs 3.6 program, then tuning for performance
Does anyone know any trouble I'll run into reprogramming the ECU?
I'm assuming you're working with HPTuners? If so, there shouldn't be any problems tuning the ECU. I don't think EFI Live supports the V6 CTSs. Have you done any datalogging yet with the stock tune? Pretty interesting that you're able to run the 3.6 on the 2.8 ECU without any changes - I would've thought the extra 25+% displacement would be beyond the fuel injectors' and ECU's capacity to adjust the fuel trims. Any idea if the two engines use the same injectors?
 
#20 ·
Well I know your UK mot inspections are way more than the USA but I've never seen the police or insurance in this country digging around for casting and stamping numbers on an engine. Is there any difference if you swap a 2.8 for for a 2.8? The Vin engine codes won't match up either. But if you have a super nice 2.8 CTS with a bad motor can do the work yourself for say 1500 to 2000 dollars why not drop in a 3.6 for the same money? That is if it's plug and play. I mean a nice 2007 CTS might be 10k. You're 8k ahead. They are the same motor just different displacement. Now if you opened the hood and it had a small block Chevy someone might notice but still if your abs and airbags work who cares.
 
#21 ·
Alright alright, I gotcha on the no information given because no one has tried.
But you've gotta understand why I felt a little bitter. I see countless threads for other people end up nowhere on here...
I participate in another forum for my motorcycle which everyone chimes in even if it's just to say they don't know, to point someone in another direction, or give wild suggestions for possibilities! Which often does create ideas that work!


ANYWAYS! on to the good stuff!

matt, I got the clutch and pressure plate rebuilt with OEM spec materials, the flywheel was resurfaced, and I replaced the clutch slave cylinder with a Sachs

The ECU was not reprogrammed. I will be doing a baseline test, comparing tables in the 2.8 vs 3.6 program, then tuning for performance
Does anyone know any trouble I'll run into reprogramming the ECU?

Parts did have to be swapped from my old motor to the new one. They were:
Oil Pan (AWD had a hole through the middle and a different shape)
Intake Manifold (original throttle body did not fit on the new 2009 AWD intake)
Power Steering Reservoir (mounting points)
Ignition Coils (different plugs)
Knock Sensors (different plugs)
Flex Plate (2009 AWD was an automatic, my 07 is a manual, replaced this with my flywheel)
Oil Dipstick (original is shorter)
Oil Feedpipe (different angle)
Power Steering Pump (I'm not sure if there was a difference, but it was newer :p)
A few misc brackets (mounting compatibility)

Keep in mind, these items shouldn't be too much of a concern unless you're getting an incomplete engine

And yes, all of these items are up for grabs. Just send me $20 to make it worthwhile for me to take time to send it over. Or! make me an offer for something else or something unique (can be anything!)
 
#22 ·
Ya the corvette forums are that way too everyone jumps in. These cars are on their way down, expensive to maintain and low resale value. Seems a lot of the people that really modded them have moved on to newer stuff and all the posts are my car won't start key stuck is my ecu bad electrical problem I got it salvage or free on a trade 4th or 5th owner one post and never come back. There are some good die hard guys on here but seems like there's always a post about swapping in some crazy setup like a Saab turbo or v motor(which seems to of happened with tons of drama and never finished) and you never hear of it again. Props for being realistic and reporting back.
On to better stuff lol. No one in my area would resurface dual mass flywheels, didn't matter, it was junk when I got it out. Springs were broken in it and that center bushing was shot. Next time around I'm dumping for a spec 1 piece with a replaceable friction surface.
How many miles were on the newish motor? If I may ask, what did you give for it? Awd CTS or some other gm product? Good to hear that's all you had to change.

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Oh did you keep the single exhaust?
 
#25 ·
Even though you're breaking that clutch in, can you feel a difference? I really babied mine for 500 miles or so, I'm sure people hated being behind me at stop lights lol. But is it like wow this is different?
When you pulled the motor did you pull the trans with it or did you take the trans out first separately? That was such a huge pain especially that bolt behind the coolant pipe assembly that the heater hoses attach to, it looked like if you could pull it as an assembly it would be tons easier.
 
#28 ·
Ok, it's no rev video, but it's just some pics I quickly took at random spots in the swap
https://www.flickr.com/photos/alx-fletcher/sets/72157636561911063/
(towards the end of that album)

I've been very careful and critical on myself to prevent a placebo effect =p
But yes, it has more pull. Even on the highway in high gear, I can keep it there instead of downshifting.

Matt, we separated the motor from tranny because we were pulling it out of the top
Yes, mating bolts were a huge pain
We left the one right at the top beneath the coolant pipe assembly off. Got all the rest on.

AAIIIC, I gotcha. Well, hopefully we'll be getting that community soon! Would be quite cool :yup:

And back to you Matt! lol
Yes, the fuel injectors are in fact different
Even between the 07 3.6 and 09 3.6
 
#29 ·
Could be that the difference in the injector sizing is roughly the same as the difference in the displacement so it all works out OK.

HPTuners is one of the two main tuning suites that folks use for GM vehicles (the other being EFI Live, but I don't see the V6 CTS listed on EFI Live's website). Their website can you tell you a helluva lot more than I can. :) But basically, a tuner (a shop or individual) gets the software, which allows you to interface with the ECU using a laptop and the OBDII port. You have to buy a key (I think they call it a certificate) to allow you to tune an ECU associated with your VIN. (A shop can buy a more expensive certificate that would allow them to tune multiple ECUs in a given family of ECUs, but an individual would just need to be able to tune their own ECU/VIN combo.) The software gives you pretty much full access to the ECU - fuel, timing, injector scaling, engine displacement, you name it. If you don't know what you're doing you can cause just as much harm as good.
 
#30 ·
Yupp, thanks for the info AAIIIC

We are using HPtuners, just need to buy the credit for my car

Also AAIIIC, would you happen to know of any security issues or such that we would have when we flash on the 3.6 to replace our current 2.8?
Any prep work we should do in case of a fault?

Thanks



https://www.flickr.com/photos/alx-fl...7636561911063/
 
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