L86 to L8T in '19 Yukon XL Denali

[Marky Dissod]

Y'all might wanna read about the experiences of @L8T BURB.
I 'technically' get why GM won't make the L8T available in Suburbans / Y XLs / ESVs,
but maybe the L8T is too reliable compared to the L86/L87?

 

[Bigburb3500]

Y'all might wanna read about the experiences of @L8T BURB.
I 'technically' get why GM won't make the L8T available in Suburbans / Y XLs / ESVs,
but maybe the L8T is too reliable compared to the L86/L87?

I THINK, key word here is THINK, it has to do more with emissions and the intended target market for the engine. The L8T is only available in HD vehicles which has a substantially different emission regulation and is “better” because of the lesser restrictions (no AFM/Cylinder deactivation). The 5.3 and 6.2 might be more “similar” from an engineering perspective which is why they appear in the regular consumer-grade vehicles and the L8T is for HD use only.
**this is a working theory**

 

[Marky Dissod]

I THINK, key word here is THINK, it has to do more with emissions and the intended target market for the engine.
The L8T is only available in HD vehicles which has a substantially different emission regulation and is “better” because of the lesser restrictions
(no Cylinder deactivation/start-stop).
The 5.3L & 6.2L might be more “similar” from an engineering perspective which is why they appear in the regular consumer-grade vehicles,
and the L8T is for HD use only.
**this is a working theory**

Substitute 'fuel consumption' for 'emissions'; the emissions profile for the L8T is substantially similar to the 5.3L & 6.2L,
with a longer stroke and an even longer rod-ratio, for better BSFC than its smaller brethren.
However, due to CAFE testing peculiarities, a 6.6L V8 will never score better MpG vs a 6.2L or a 5.3L.

As for the 'intended' market, there are a substantial number of drivers who would drive even more conservatively with a larger engine MOST of the time,
while appreciating an engine that would last far longer, yet still be ready to work (or play) harder when asked,
than an engine busy pretending to be smaller than it is by using less than 8 cylinders.

Cylinder valve deactivation is not for us - it's for CAFE. By the same token, the L8T is kept from most of the civilian population.
(Separate question: why can't civilians have rubber floors that take 5min to clean with running water, as an OPTION?)

 

[L8T BURB]

@chevman88 This is awesome! The L8T mated to the 10 speed will be amazing. I can't wait to hear about the driving impressions once the tune is honed in.

If you want insight from someone who has done numerous L8T swaps and can tune them with ease, reach out to Kevin at Big Dog Tuning. 662-213-6424. He had my tune dialed in and is very reasonably priced.

 

[Bigburb3500]

Substitute 'fuel consumption' for 'emissions'; the emissions profile for the L8T is substantially similar to the 5.3L & 6.2L,
with a longer stroke and an even longer rod-ratio, for better BSFC than its smaller brethren.
However, due to CAFE testing peculiarities, a 6.6L V8 will never score better MpG vs a 6.2L or a 5.3L.

As for the 'intended' market, there are a substantial number of drivers who would drive even more conservatively with a larger engine MOST of the time,
while appreciating an engine that would last far longer, yet still be ready to work (or play) harder when asked,
than an engine busy pretending to be smaller than it is by using less than 8 cylinders.

Cylinder valve deactivation is not for us - it's for CAFE. By the same token, the L8T is kept from most of the civilian population.
(Separate question: why can't civilians have rubber floors that take 5min to clean with running water, as an OPTION?)

You would love my current Suburban. 6.0 Vortec, LT trim with all the goodies… except cooled seats which sucks, but it has rubber floors. Freaking love it! You just completed my rant I have on a regular

 

[2015TahoePPV]

make sure you don't have an injector harness stuck between the block and the trans, that could cause your issue and you definitely don't want to tighten down on that. If its all clear, lift the trans a little with a floor jack with the engine on the mounts hovering just over the frame and use a couple of bolts to finish mating it up. You shouldn't need to really apply much torque to bring it home. If your mounts are already on the frame, then the angle between the engine/ trans might be causing a little pinch.

 

[chevman88]

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.