Allison trasmission conversion????

[HUMMERDAD]

OK I has anypne heard of or seen this done on the H2 I know this is a popluar combo for the diessel swaps but what about just the trans itslef? I was a trucker for for many years before going into the service and know the allison well. I have been looking into rebuilding the stock unit swaping it with the 4L80E unit like MUD suggested thank you again mud, It just seems that if they make all the wireing, and mounts for the duramax, why don't they make anything for the gasoline engines?

 

[MaxPF]

OK I has anypne heard of or seen this done on the H2 I know this is a popluar combo for the diessel swaps but what about just the trans itslef? I was a trucker for for many years before going into the service and know the allison well. I have been looking into rebuilding the stock unit swaping it with the 4L80E unit like MUD suggested thank you again mud, It just seems that if they make all the wireing, and mounts for the duramax, why don't they make anything for the gasoline engines?

They did mate it to the 8.1L gas engine. If you bought a 2500, 3500, 4500, or 5500 with the 8.1L L18 engine, it had an Allison behind it. It's easily mated to and run with an LQ4 6.0L - you just need the 8.1L PCM (or flash the 8.1L OS into your existing PCM) and the 8.1L TCM, with a bit of EFI Live work on both. The L92 6.2L in the 08-up models is a "maybe" - if they support the same torque and defuel messages as the DMax, then a DMax TCM could be used. Otherwise, the 8.1L TCM would have to be used in standalone mode with a slave digital TPS on the throttle pedal.

The biggest problem is that it probably won't fit in the trans tunnel on the H2. This is the reason they aren't used in vans and suburbans - those apps get the physically smaller 4L85E and a derated engine. Also, the Ally is a bit more of a parasite than the 4L80E/85E. It weighs more than twice what a 4L80/85E does, It has a larger pump, runs at higher pressures up to 4th gear, and has much heavier internals with more rotating inertia. This means your in-town mileage may drop a bit.

 

[[__--MUD--__]]

The biggest problem is that it probably won't fit in the trans tunnel on the H2. .

it wont fit as a direct swap, that is why all the diesel converted H2s are running 2" body lifts. I have no idea where the allison runs out of space in the tunnel...its obviously a height issue, but there is a hell of alot of unused space under the center console that also could easily be cut out and reboxed.

 

[twinmill28]

What Mud said, but there is that whole PCM thingy that Max was talking about (were you the nerd in 3rd grade?)---I'm thinking that's going to take some brain power to sort out, and that's given that you don't run into a dead end finding out it just won't be compatible electronically for some reason after you've shoe horned that heavy damn thing in.
Interesting concept none-the-less, well, other than being so much heavier.
Seems like beefing up what you've got is a much more logical fix if you're not running ooodles of power.

 

[MaxPF]

What Mud said, but there is that whole PCM thingy that Max was talking about (were you the nerd in 3rd grade?)---I'm thinking that's going to take some brain power to sort out, and that's given that you don't run into a dead end finding out it just won't be compatible electronically for some reason after you've shoe horned that heavy damn thing in.

There is zero chance of it not working. HUMERDAD has an 04, which means it has a gen III PCM. The gen III PCM and the Allison (both 5 and 6 speeds) are a factory combination. Which is why I say there is a zero chance of it not working.

FWIW, I figured out how to make a GM 6 speed TCM work stand alone when all the "experts" said it was impossible. I have a big sticky thread over on 4BT Swaps dedicated to it. So, I know what I am talking about when it comes to the Allison.