L8T 6L90 4.11 on 37s

[Acrosteve]

20250309_154207.jpg20250309_154207.jpg


I can't claim credit for the tune. Just showing numbers for reference.



Dyno guy was very surprised by those numbers. 381/488 on 37s
He figured it would be lower because of the big tires.


He figures 20% loss for the powertrain. If that's true, that's about 480 at the flywheel.

Stock internals.

[TrkNrrs]

I?d be curious to see the dyno it was on.

[Acrosteve]

Dynocom performance model

It's just a heavy drum. No brake or load other than spinning the 5k lbs.

He usually starts his tests at 3k, but did this one at 2500.

[pronstar]

Very surprising?big tires kill wheel hp

[TrkNrrs]

Ahhh no load.

[Acrosteve]

Not entirely true. The load is the inertia of a 5,000lb drum accelerating to 99mph with a rolling start in 3rd gear.

[TrkNrrs]

Throw that puppy on a mustang dyno.

[OneOfZero]

L8T BTR 220 vs Stock.png

Good numbers. I'm putting a L8T in a 2015 Sierra in a couple of weeks, with the BTR 220 Cam and full headers/exhaust and a Circle D 2800-3000 converter. Hopefully that attachment works... BTR made 588hp/591tq with this cam. Should be a fun truck.

Did you guys that have done this swap use the stock harness? I do have a Holley oil pan on it and it doesn't have the provision for the oil level sensor. Other than that and the DoD stuff, I think the stock harness should be good. Any pointers pre-swap would be appreciated.