6.6 Gas L8T Engine Swap in 2015 Suburban

[minytrker]

I hadn't gave the rear axle much thought. My thinking was that this power train is SOMEWHAT similar in power to the 6.2, so I was hopeful I could maintain my stock rear.

After some research online, I think I may have 3.08 gearing, and it appears the 6.2 Suburbans have 3.23. So I may not be TOO far off.

wont be an issue...have put blowers on several and have a blower on mine with no issue at 500hp

 

[L8T BURB]

UPDATE!!

Engine and 6L90 trans are in! Front clip is back on! Now we are down to the tuning and driveshaft. Technician stated that there was around 50 error codes when it was first started, and he quickly got it down to under 20 codes. I'm not savvy in tuning whatsoever, but he says that's a great step lol! He mentioned that he's having a little issue getting the 6L90 to communicate with the vehicle. I'm hopeful that we can get that resolved. We have used all harnesses and ECM/TCM from the 2015 Suburban. He is attempting to use the 6.6 intake and throttle body. Time will tell if he can get those systems talking to the 5.3 ECM properly. He had to modify the transmission cross member to accommodate the additional size of the 6L90. Seems the only things remaining are dialing in the tuning, and getting the proper slip yoke, and custom driveshaft built. I'm VERY excited!!

 

[Tonyrodz]

UPDATE!!

Engine and 6L90 trans are in! Front clip is back on! Now we are down to the tuning and driveshaft. Technician stated that there was around 50 error codes when it was first started, and he quickly got it down to under 20 codes. I'm not savvy in tuning whatsoever, but he says that's a great step lol! He mentioned that he's having a little issue getting the 6L90 to communicate with the vehicle. I'm hopeful that we can get that resolved. We have used all harnesses and ECM/TCM from the 2015 Suburban. He is attempting to use the 6.6 intake and throttle body. Time will tell if he can get those systems talking to the 5.3 ECM properly. He had to modify the transmission cross member to accommodate the additional size of the 6L90. Seems the only things remaining are dialing in the tuning, and getting the proper slip yoke, and custom driveshaft built. I'm VERY excited!!

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Sounds like great news. Can't wait to see a video of this beast showing what she's got.

 

[adventurenali92]

This is gonna be real badass when it’s done…..

 

[TollKeeper]

Looks like it was meant to be there... Power Steering working?

 

[Tiredmechanic23]

Have been thinking going this way when my 5.3 dies. Glad im not the only one. Engine bolted up to existing fame mounts? If so thats the part I was most concerned about. We have 4 2022-2023 2500s at work with the 6.6 I use daily and they do great other than on gas mileage. If the TB wont play nice a 6.2TB and I believe it will bolt right up as the 6.6 I think has the same manifold as the 6.2. I already run a 6.2 TB and manifold on my 5.3.

ill be watching this thread until done now!

 

[L8T BURB]

Here again with another update!!

It is now running, and has NO codes! We've been waiting for the driveshaft to be built, and just got it back today. My technician says he'd like to log around 100 miles on it to work out any miscellaneous issues that may pop up in tuning or otherwise.

Keep in mind, this is a 6.6 engine and a 6L90 trans...neither of which were ever meant to be in this vehicle, so hearing it run was pure music to my ears!!

The only issue we have left to deal with is the intake/throttle body. My ECM didn't seem to like the 6.6 throttle body, so we installed the 5.3 intake and throttle body on the 6.6 and it ran good with no codes. The intake on the 6.2 and 6.6 are identical part numbers from GM, but different throttle bodies. So I grabbed a throttle body from the 6.2 to see if we can get it talking with the 6.6 intake and my ECM.

I am attaching a few pics of the driveshaft differences, and one pic (all I could get) of the Suburban. Peep the MASSIVE difference on the slip yoke end of the driveshaft. This new one is beefy! It's made of 1/8" aluminum, and it's so much thicker than the stock, it sounds and FEELS metal. I'd hate to think how thin the factory shaft is. More details to come!!

 

[adventurenali92]

Here again with another update!!

It is now running, and has NO codes! We've been waiting for the driveshaft to be built, and just got it back today. My technician says he'd like to log around 100 miles on it to work out any miscellaneous issues that may pop up in tuning or otherwise.

Keep in mind, this is a 6.6 engine and a 6L90 trans...neither of which were ever meant to be in this vehicle, so hearing it run was pure music to my ears!!

The only issue we have left to deal with is the intake/throttle body. My ECM didn't seem to like the 6.6 throttle body, so we installed the 5.3 intake and throttle body on the 6.6 and it ran good with no codes. The intake on the 6.2 and 6.6 are identical part numbers from GM, but different throttle bodies. So I grabbed a throttle body from the 6.2 to see if we can get it talking with the 6.6 intake and my ECM.

I am attaching a few pics of the driveshaft differences, and one pic (all I could get) of the Suburban. Peep the MASSIVE difference on the slip yoke end of the driveshaft. This new one is beefy! It's made of 1/8" aluminum, and it's so much thicker than the stock, it sounds and FEELS metal. I'd hate to think how thin the factory shaft is. More details to come!!

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Of course ya left us hangin with no videos of sound?!?! Cliff hangar…. Lol

 

[L8T BURB]

Of course ya left us hangin with no videos of sound?!?! Cliff hangar…. Lol

Sorry! It's been such a crazy couple of weeks. I dropped the ball and didn't think to buy new engine mounts until the 6.6 was already installed, DOH!!

Also have gotten upper/lower control arms, inner/outer tie Rods, shocks and struts on front and rear, serviced rear diff fluid. This thing should be like a new rig when I get it back.

I assure you guys that when it's back in my possession, I will provide ALL the good information. Including videos, many pics, and a complete pricing breakdown of it all. There will be no stone unturned, just bear with me guys!!

I've also got a plan in place to do what I'm calling an "rst conversion" of exterior mods. Trying to think one step at a time here, but it's tough!!

 

[L8T BURB]

To answer a couple of previous questions...

The power steering works just as it did before! We simply discarded the power steering pump assembly on the 6.6.

Also the 6.6 does not have provisions on the block for the belt driven vacuum pump that operates the braking system, so we tapped into the pcv to get vacuum for the brakes, and it's smooth!

Again, sorry for the irregular updates. The end is near though!!