@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.
L86 to L8T in '19 Yukon XL Denali
- Thread starter chevman88
- Start date
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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
Full Access Member
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
Full Access Member
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!
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.
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.
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!
Marky Dissod
Full Access Member
Is the L86 throttle body smaller than the L8T's throttle body?
They look to be the same size, just figured I would try and use the newer one.
Took it out for a test drive this afternoon, can definitely feel the torque difference. Brakes work just as well as they did before. Got the codes narrowed down to p0443 and p0458 which are both evap related (the one connector I managed to break) and a sporadic p2534 for ignition circuit low.
Planning on reseating the purge valve as I transplanted it from the L86 intake to the L8T and verifying the connector has good readings.
For the ignition circuit I'm not sure as it's sporadic, but I'll start by verifying I reattached all of my grounds.
Figured out the evap codes, one of the pins was bent and wasn't seating where it should, was able to bend it back and it looks like those codes are gone. I've got some misses at idle still, so I'm going to swap all of the L8T coils on since they're newer (wires and plugs are new)
What did you use for a tune? I'd assume you could just get a base map from an HD pickup and then copy and paste the corresponding tables in for spark, fuel, etc. I'm relatively new at tuning my own stuff......it's way different than a test cell full of all kinds of gadgets. Keep us posted. This is awesome!
Still couldn't get ahold of Kevin, but I think I found one of his tunes posted on the hptuners forum that I copied the fuel and spark tables from. I need to schedule some dyno time to actually get it tuned.
It's been a bit since the swap, wife REALLY likes the better torque. She didn't think about it while trying to turn left through an intersection and had to gun it, squeeled the tires and scared herself a bit, hahaha. I did end up swapping the driver side valve cover back in to utilize the built in PCV valve and just teed off it to connect the vacuum booster and capped the driver side air box inlet for the L86 valve cover breather. Got a Dyno scheduled for next week (may need to reschedule due to existing conflicts that I didn't realize) so I'm excited to see what numbers she actually puts down.
First tank of fuel through and MPG is definitely down averaging just over 13MPG with mostly city driving. According to Fuelly, it's on the lower end, but still within average of the bigger 2500s with this motor.
First tank of fuel through and MPG is definitely down averaging just over 13MPG with mostly city driving. According to Fuelly, it's on the lower end, but still within average of the bigger 2500s with this motor.
Bigburb3500
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Super curious to see long term MPG figure with this hooked to the 10speed. Also, can’t wait to see your power number too! Will be a great write up.
adventurenali92
Full Access Member
Can we get some sound clips?!?! I’ll bet she sounds like a beast! I love the idea of swapping out the 6.2 for an L8T 6.6!!! Wish I could do it haha.
On my L8T swap, my Suburban was a PIG around town as far as MPGs go. The torque down low in city driving was insane though! The MPGs did seem to improve greatly on highway travel. I had the 6 speed transmission behind my L8T though. I would imagine the 10 speed will return better MPG and an overall improved driving experience.
Marky Dissod
Full Access Member
@L8T BURB, did you upgrade the axle gear, or did you keep 3.08?
Your metro/urban city MpG likely would have been improved by 3.42.
