6.6 Gas L8T Engine Swap in 2015 Suburban

[Marky Dissod]

The L8T engine uses a hydraulic power steering system rather than electronic on the Suburban.
Would it be easy to ditch it for electronic, or better to convert my Suburban to hydraulic?

I would not be surprised if the aluminum blocks lack the ability to hang power steering onto them, whereas only the iron block L8T would have such bosses to mount power steering.
Long story short, prepare to go hydraulic, unless you are willing to swim uphill for 2 or 3MpG.

Also I noticed the L8T has a mech cooling fan, belt-driven, rather than the electronic cooling fan on my Suburban.
Any idea if this would be an issue?

If the L8T & your 5.3L engine both use very similar or identical pcms, you'll wind up with the ability to choose between electronic fans with pcm control, or mech fan.If you tow HEAVY, mech fan. If not, electronic fans.

The engine/trans I'm looking at comes with all accessory drive components as well as ECM.
It's as complete as an engine swap could be.

And I bet dollars t' donuts the transmission attached to the L8T comes with its own tcm too.
USE THOSE!
To be clear: lean very heavily toward using the L8T's engine AND transmission control moduleS if at all possible.

Save your 5.3L ecm & tcm.
If they are BOTH sufficiently similar to the L8T's ecm & tcm, keep and use them for custom tuning purposes.

Sell your 5.3L engine -unless you want to keep it (for future upgrades?).
Keep your 5.3L's transmission to use as a core, or upgrade-rebuild it.

 

[B-train]

This is an AWESOME thread! I'm super excited to see how it works out. You may have opened pandoras box to making these SUVS bullet proof and long lasting w/o the CAFE BS that plagues them with age.

Thanks for taking the leap for us!

 

[CMoore711]

I am also interfacing with someone on the HP tuners forum who has successfully done this swap on a Sierra Denali 1500. This was his response...

It will be an awesome swap. My daily is a 2016 Sierra Denali with a 6.6L swap. If you can get the complete engine, that would be the way to go. In your case, you can use your original ECM and wiring harness. You'll just have to swap your original 4 pin fuel rail sensor instead of the 3 pin sensor on the L8T.
The vacuum pump will have to be deleted as well, since the L8T doesn't have mounting provisions. That's an easy job as well.

Thoughts?

Thanks all!

Michael

Boom goes the dynamite.

Between this guys experience and your technician/tuner telling you it’s doable I’d say order the L8T motor and transmission and do it.

 

[L8T BURB]

The next point of contention here looks to be whether the 6L90 transmission could be made to fit my Suburban? The donor L8T comes with a 6L90 attached to it. Both my Suburban and the donor are 2WD. Of course my Suburban has the 6L80.

Any insight on what would need to be done? Perhaps shorten the driveshaft?

I am currently negotiating with the seller on the L8T donor. Will update once I secure it!

 

[Geotrash]

The next point of contention here looks to be whether the 6L90 transmission could be made to fit my Suburban? The donor L8T comes with a 6L90 attached to it. Both my Suburban and the donor are 2WD. Of course my Suburban has the 6L80.

Any insight on what would need to be done? Perhaps shorten the driveshaft?

I am currently negotiating with the seller on the L8T donor. Will update once I secure it!

The 6L90 is longer but I believe the mounts are in the same place so all you should probably need to worry about are having a shorter driveshaft fabricated and perhaps adapting the u-joints.

 

[strutaeng]

So sounds like the typical GM LS/LT swap, i.e., "plug and play!" LOL

 

[Marky Dissod]

The variances between the 6L80E & 6L90E can likely be handled by a different driveshaft, a rubber mallet, and patience.
Can you make use of the 6L90E driveshaft that already came with it? Or do you need a different other one?

 

[L8T BURB]

The variances between the 6L80E & 6L90E can likely be handled by a different driveshaft, a rubber mallet, and patience.
Can you make use of the 6L90E driveshaft that already came with it? Or do you need a different other one?

The donor vehicle with the L8T is not available for me to get the driveshaft from. I talked to my technician today and he suggested that (if needed) we could utilize a driveline shop that's the next town over and have them cut down the driveshaft. Feeling pretty good about this! In the final negotiating stage, all signs lead to me finalizing this deal tomorrow morning and freight to the shop by midweek next week!

 

[L8T BURB]

UPDATE!!

Engine/transmission has been purchased! The seller will be palletizing and prepping for shipment by weekend, and I should receive it by the middle of next week! I'm freaking PUMPED!!

Here are some pics of the donor vehicle and engine/transmission...

 

[L8T BURB]

Some more pics...