Major upgrades GMT800, 06ish XL 2500

[lowderkg]

Newbie here. Gonna buy 2003--2006 Yukon XL, SLT W/ 8.1. Once rig here, one of the big "to do" on bucket list is upgrade tyranny to best there is. Forgive my Naiveté as relates to engine/tranny/rear end. But would it be possible to upgrade from 4 speed to like a 5-6 speed, ie 6L90 ? If I have posted this in wrong place, I apologize. I am just on a mission to have a kick butt ride. Thank you for any thoughts and suggestions.
Lowderkg

 

[strutaeng]

I believe the only way to upgrade to the 6 speed on the GMT800 is via a Holley aftermarket ECU and that requires a 58X reluctor wheel on the crankshaft, which means pulling the engine and complete disassemble. This on the LS-based engines, and I'm assuming it still applies to the 8.1 since it's kinda of like a hybrid but still uses LS electronics. Maybe you can call Holley and ask them?

What gears do you have on it? 3.73 or 4.10?

I've toyed with the idea of swapping an 8.1/Allison 5 speed on my project 04 Suburban 2500 6.0/4L80e, but it's just thought at this point.

You can do a supercharger, turbo or something else from Raylar such as a larger bore/stroker/cam/aftermarket heads. Lawrence Tolman has modified a few 8.1s. Check out his channel on YT. That's probably a $8,000-$10,000 upgrade on the NA option.

You can get a lot more power on the turbo (especially if you do the work yourself) for cheaper on a HP/$ ratio, especially with these cheap chicom turbos that are so affordable these days.

 

[Marky Dissod]

Gonna buy 03-06 Yukon XL, SLT W/ 8.1L.
Once rig here, one of the big "to do" on bucket list is upgrade tyranny to best there is.
Forgive my Naiveté as relates to engine/tranny/rear end.
But would it be possible to upgrade from 4L80 to like a 5-6 speed, ie 6L90?
If I have posted this in wrong place, I apologize.
I am just on a mission to have a kick butt ride. Thank you for any thoughts and suggestions.

Upgrade tyranny? That kind of political talk can get you summarily banned at this 'forum' - a bit of a weird irony ...
ANYWAY

If your pcm can operate a 6L90 ... actually I THINK the 6L90 requires an ecm for the engine and a tcm for the 6L90?
Meaning you might need a major wiring harness overhaul, maybe a few other modules would need an upgrade.
Involved, but definitely doable.
You may be better off considering the Allison 6speed, the one that lots of people think is a five speed,
but becomes a 6speed after a tune?

What, specifically, do you mean by 'kick @$$ ride'?
Most people who don't know what they're really getting into say, 'x amount of horses',
instead of understanding how quick they want to cover the 1/4 mile, for example.

Are you more interested in towing/hauling strength, instead or high RpM power?
How much further off-road do you want to be able to go?

Define your terms.

 

[mikeyss]

Gen I and II Chevrolet and Buick Engine 6L80E/6L90E 6 Speed Conversion Kit - Zero Gravity Performance

GM Gen 1 and 2 Chevrolet 6L80E 6L90E Conversion Kit. Comes with a 6L80e or 6L90e Transmission Torque Converter, TPS kit and TCM2650 Gateway Module

www.zerogravityperformance.com

Seems the 6L80/6L90 swaps are becoming easier.

 

[Fless]

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