L86 to L8T in '19 Yukon XL Denali

[chevman88]

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.

 

[chevman88]

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)

 

[L8T BURB]

How is the tune coming along? Wonder if some revisions of the tune could smooth out the issues at idle, or do you think it is a mechanical defect?

 

[B-train]

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!

 

[chevman88]

How is the tune coming along? Wonder if some revisions of the tune could smooth out the issues at idle, or do you think it is a mechanical defect?

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.

 

[chevman88]

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.

 

[Bigburb3500]

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.

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]

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.

 

[L8T BURB]

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]

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! MpGs did seem to improve greatly on highway travel.
I had the 6L90 behind my L8T though.

@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.