I'm still set on goin with the 8.1l over the 6.0. I think after all i've found out its gonn be easiest to go w/ a 2500hd instead of swaping the 8.1 in2 a half ton chasis. My question is this... the 8.1l comes w/ the allison and the allison has its own control module. If you get the 6.0/4l80e its all controlled by the pcm. I'd would think that it would be easier to get a 6.0/4l80e and swap the 6.0 for the 8.1 than it would b to swap an allison for the 4l80e. I'm not to keen on the allison as 30-35% hp loss seems to be about what people are seeing. compare to about 25-28% loss w/ the 4l80e. I know the 4l80e comes w/ the 8.1 in the suburbans so if worse come to worse i could always find a wrecked burb and buy the pcm, engine and harness outa that, but that would takes lots of time 2 find one. I was wondering if any of you knew if the pcm that comes w/ the 6.0 will work with the 8.1. I've noticed lots of you guys swaping ur 4.8's and 5.3's fer the 6.0. If you use the same pcm, because it makes me think that it may work for the 8.1. I plan on moding the truck afterwards and being able to control the trany as well as the engine through the pcm would be nice (hopefully w/ the new hptuner program). The motor mounts and accesories will all work because the trucks designed to have the 8.1. Plus with more room in the engine bay of the 2500hd i'll have room fer a set of intercooled twins

 

I'd check with Tom at Tbryne motorsports. He has a couple of big block NBS trucks (1 truck and 1 suburban) that run real strong. He is also a sponsor to this site and has always been very helpful and straight forward. I believe he has a intercooled Vortech on his suburban. His link is on the right--------------------------->