6.6 Gas L8T Engine Swap in 2015 Suburban

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

adventurenali92

Full Access Member
Joined
Feb 16, 2015
Posts
7,414
Reaction score
8,660
Location
Big Bear Lake, ca
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!!
Dannngggg she’s gonna be brand new after that! That’s a ton of work! Well awesome! :popcorn:
 
OP
OP
L8T BURB

L8T BURB

Full Access Member
Joined
Jul 3, 2023
Posts
125
Reaction score
315
Location
Kentucky


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
 
Last edited:

Tonyrodz

Resident Resident
Joined
Feb 16, 2012
Posts
31,706
Reaction score
47,430
Location
Central Jersey


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
Wish I could give you 1,000,000 thumbs up! Sounds great. Your guy really figured it out. As for the cats--I'm also running cables on my 03. They're also deleted in my tune along with the downstream o2s. I also have the gas smell while it's running. Unfortunately I think it's unavoidable once the cats are gone. I wouldn't be surprised if you get an o2 cel.
Did your mechanic give her the "onions"? Lol, does she have some more noticeable power?
 
OP
OP
L8T BURB

L8T BURB

Full Access Member
Joined
Jul 3, 2023
Posts
125
Reaction score
315
Location
Kentucky
Wish I could give you 1,000,000 thumbs up! Sounds great. Your guy really figured it out. As for the cats--I'm also running cables on my 03. They're also deleted in my tune along with the downstream o2s. I also have the gas smell while it's running. Unfortunately I think it's unavoidable once the cats are gone. I wouldn't be surprised if you get an o2 cel.
Did your mechanic give her the "onions"? Lol, does she have some more noticeable power?
My technician stated that he has "turned off the o2 sensors". My assumption is that this means I won't get any check engine light. All o2 sensors are still in place, just with gutted cats. The particulate or whatever it is that came out of the cats was wild looking! Chunks of white and gray stuff.

As for power, he didn't push it hard. On the short 3 mile loop, he got it up to 80 mph, but was a gradual acceleration. He noted he was pushing it to maybe 50% throttle, and it did feel VERY strong and was very smooth! Just from the passenger seat, it felt nearly as strong at "maybe 50% throttle" as my 5.3 felt under full acceleration. Of course I was just very giddy, so my opinion may vary once I get it back this weekend.
 
Last edited:

Tonyrodz

Resident Resident
Joined
Feb 16, 2012
Posts
31,706
Reaction score
47,430
Location
Central Jersey
My technician stated that he has "turned off the o2 sensors". My assumption is that this means I won't get any check engine light. All o2 sensors are still in place, just with gutted cats. The particulate or whatever it is that came out of the cats was wild looking! Chunks of white and gray stuff.

As for power, he didn't push it hard. On the short 3 mile loop, he got it up to 80 mph, but was a gradual acceleration. He noted he was pushing it to maybe 50% throttle, and it did feel VERY strong and was very smooth! Just from the passenger seat, it felt nearly as strong at "maybe 50% throttle" as my 5.3 felt under full acceleration. Of course I was just very giddy, so my opinion may vary once I get it back this weekend.
That particulate that came out of the cats is what's so valuable--the reason cats are stolen. I also gutted one of my cats on my Express van due to it being clogged. It also has that gas smell while idling.
 
OP
OP
L8T BURB

L8T BURB

Full Access Member
Joined
Jul 3, 2023
Posts
125
Reaction score
315
Location
Kentucky
That particulate that came out of the cats is what's so valuable--the reason cats are stolen. I also gutted one of my cats on my Express van due to it being clogged. It also has that gas smell while idling.
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?
 

Tonyrodz

Resident Resident
Joined
Feb 16, 2012
Posts
31,706
Reaction score
47,430
Location
Central Jersey
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?
Hard to say about the smell coming inside. In my experience I've both smelled it coming inside, and other times I haven't noticed anything. Guess you'll need to feel it out. It's always easy enough for your guy to weld in the other cats if needed.
 

adventurenali92

Full Access Member
Joined
Feb 16, 2015
Posts
7,414
Reaction score
8,660
Location
Big Bear Lake, ca
Dang that’s rad sounding suburban right there! Heading to YouTube to hit follow cuz I wanna see every video you make about this thing! Definitely a unique K2 suburban you built yourself to roll around in!
 

Forum statistics

Threads
132,739
Posts
1,873,427
Members
97,567
Latest member
a9lyphe
Top