6.6 Gas L8T Engine Swap in 2015 Suburban

[CMoore711]

The gutted cats is a new thing for me. Never had a vehicle with them before. Do you ever smell that gas odor inside the cabin? Reason I ask is because I do have access to all 3 converters that came with the 6.6 engine that I could have welded onto the 5.3 downpipe. The reason we didn't use them in the first place was because the manifold angles were so different that the 6.6 manifolds wouldn't physically clear the firewall area. I'm not sure I'd be a fan of the gas smell inside the cabin of the Suburban.

Thoughts?

I know the 5.3L K2XX SUV’s have 3” diameter factory cat-back exhaust pipe and 6.2L have 3.5” diameter factory cat-back exhaust pipe. Wonder what diameter cat-back exhaust pipe came on the 6.6L L8T HD trucks? If it’s 3.5” you may want to consider an exhaust upgrade?

Either way all that cutting and welding seems like a lot of work for factory exhaust manifolds and cats. To me it just sounds like a really good and justifiable reason to throw on some 1-7/8” long tube headers, a catted Y pipe, and an upgraded 3.5” cat-back exhaust.

 

[B-train]

Update!!! I got a call from my technician today saying that he was "currently on the maiden voyage". He said the catalytic converters plugged up very qucikly into the first drive. Noting the notorious rotten eggs smell. He got it back to his shop and knocked the guts out of all 3 cats. The rest of the exhaust is still intact. Stock muffler, stock resonator, stock piping throughout. Note that the cats are still "technically" there, but there's nothing inside of them.

I got to hear it start a few times, and got to ride passenger in it! My tech didn't push it hard. About a 3 mile loop just to confirm the cats were cleared so he could continue to dial in the tune. The only downside I've seen so far is that there appears to be a light fuel odor when outside of the Suburban. Time will tell if that's due to the cats being gutted, or possibly a rich tune.

I have attempted to create a YouTube channel and uploaded the 2 short videos I captured today. It is scheduled to get an alignment at our local Chevy store in the morning due to all the steering and suspension parts that were replaced. All signs lead to me getting it back in my possession Friday! I promise PLENTY more videos to come that will be very descriptive and worth watching!

PLEASE PLEASE PLEASE give me a like, comment and subscribe! Channel is L8T_BURB

All new vehicles run rich to keep the cats hot, kind of an oxymoron if your focus us efficiency. If he's good at tuning, which it seems like, then you could try for more of a lean tune and see if that helps. I don't think pulling a smigion of fuel out will make any sort of problems, plus it may actually be snappier.

Just a thought.

 

[Thrust]

Sweet! Glad you got it all working. Sounds like you need to make your own kit/tune package to sell for anyone else wanting to do this swap.

 

[TollKeeper]

Wonder how long before someone asks if you want to sell it?

Wanna sell it? J/K!

 

[L8T BURB]

We ran into a little hiccup with the tuning. ECM is still commanding too much fuel, causing a rich condition. We have Kevin Winstead, owner of Big Dog Tuning from Ripley, MS that's going to take a look at the tune file tomorrow and hopefully get it corrected for us. Kevin has done several 6.6 long block swaps so he's very familiar with this setup. We are still very close!

 

[L8T BURB]

Sweet! Glad you got it all working. Sounds like you need to make your own kit/tune package to sell for anyone else wanting to do this swap.

My tech has access to all the tuning stuff, but in his own words, his tuning is "educated guesses". We are now calling on Kevin Winstead from Big Dog Tuning to get the tune dialed in. He quoted just $150 for a remote tune of this application which seems VERY reasonable.

 

[L8T BURB]

Wonder how long before someone asks if you want to sell it?

Wanna sell it? J/K!

I don't even know where I'd start at on a price lol! I plan to be FULLY transparent with all my expenses when I get it back. As much money as I'll have in this, I probably ought to keep it till I die, or I may end up divorced!!

 

[L8T BURB]

Did somebody say cold start???

 

[Trey Hardy]

My tech has access to all the tuning stuff, but in his own words, his tuning is "educated guesses". We are now calling on Kevin Winstead from Big Dog Tuning to get the tune dialed in. He quoted just $150 for a remote tune of this application which seems VERY reasonable.

That’s a very fair price my tuner friend which I’ve known and dealt with for 10+ years usually only charges me 100-150$ mainly for the initial credit to get into HP tuners and 25-50$ for him tuning it for me. Anything after that he usually does for free but I throw him cash for his time and trouble when we have had to adjust stuff

 

[TollKeeper]

Did somebody say cold start???

And your asking how much for it?