L86 to L8T in '19 Yukon XL Denali

[L8T BURB]

Mounts are in and trans is mated. Just replaced the passenger motor mount so I still have the one parts store special on the driver side, but I didn't feel like swapping it out since it is fully installed. Didn't realize the harmonic balancer was a one time use TTY bolt, so have another one on the way that should be here tomorrow. Should be able to wrap this up after work by the end of the week and have it on the road. I've gotta work around the weather as I'm working out of a smaller 2 car garage that requires the door to be open when working on it.

My thoughts behind this swap is a more reliable family daily that can tow. MPG will be what it is, be it better or worse.

@L8T BURB - I reached out a bit when I first started and got notta for response, but I'll try again. Push come to shove I've got a basic L8T file to get me started.

@chevman88 He usually lets calls go to voicemail if it's a number he doesn't recognize. Be sure to leave a detailed message and call back number. He is usually quite prompt in communicating.

 

[RST Dana]

This is just too good to be true… can make any old GM a “new” vehicle with just bolting in new items… can’t wait to hear how the truck runs!

He didn’t bolt up any old GM block. He wouldn’t be needing a “tune” file with a 1970ish BBC bolted up!

 

[chevman88]

He didn’t bolt up any old GM block. He wouldn’t be needing a “tune” file with a 1970ish BBC bolted up!

This is true, the bell housing bolt pattern is slightly different from gen4 and prior. Instead of the 6-7 bolts (2 on each side surrounding the dowels, 2 further up on the angled portion and maybe one at top center) there are now 8 bolts (2 from oil pan, 2 on each side surrounding dowels, 1 slightly off top center and one driver side on the angled portion). I'm sure there's a way to adapt them to make it work with older style bolt patterns, but it's not 1 for 1. I'll upload a picture of the newer one when I get home and can take a picture of the back of the L86. The HPFP drive prevents the top center bolt, so it's now slightly offset.

 

[tooleyondeck]

The more I am seeing these swaps, the more I want to intentionally find a K2X with a bad motor specifically to do this...

 

[Walkerfever]

Great, now I'm weighing the Cost Vs Benefits of an L8T swap vs pulling and doing a DOD delete on my L83. Thanks to @L8T BURB and @chevman88 for their awesome threads!

 

[chevman88]

Ran into another little snag. IF you are looking at doing this swap, compare connectors on everything that integrates with your harness BEFORE dropping the L8T in. I elected to keep the L8T oil pan in place rather that pull it and reseal (with my luck it would start leaking a week or two after I were to get it all running), what I didn't realize is that I have a different style oil level sensor and this is NOT easily replaceable (have to pull the pan...go figure). The pig tail needed for the style on my L8T pan is GM part 13587326, I'm going to splice it in and hope that the values this sensor provides are compatible.

L86 sensor is part 12696434
L8T sensor is part 12676061

I was able to get away with not needing to swap the fuel pressure sensor as I already have a 3 wire from the factory, but it's important for anyone looking to do this to verify what they have and what needs to be swapped over. Had I realized the sensors were different I would have just swapped the pans.

 

[chevman88]

Just about got this wrapped up. Ended up smashing the purge valve solenoid connector so had to make another stealership run. For vacuum I swapped the L86 driver valve cover over and tied into the old PCV valve port on the intake. I took apart the old hose and reused the connector on the brake booster line and now the valve cover hoses will function more as a breather tied into the intake pre-throttle body. Hoping to get a first fire tonight!

 

[chevman88]

All assembled! Time to fill her up with fluids and install the initial tune! Planning on reinstalling the valve cover covers after verifying everything looks good as well as giving this dirty engine bay a bath

 

[chevman88]

She lives! Got it fired up and had quite a few codes - definitely had to change the throttle body back to the L86 one, still have a few more codes to figure out, but it started and ran for the first time in over a month!