Big Block SUT

[Bhplumber]

Hey everyone, Im looking for any info you have on swapping a 8.1 and Allison into my SUT. I have read the thread about juicing up the 6.0 but what I really want is the Allison tranny and more power of course. I figure if I go with the 8.1 I can get plenty of power, the Allison, and a part time t-case hopefully without quite as much expense and hassle of swapping in a duramax. Im not really looking to gain gas mileage although it would be nice. I also want the reliability of a factory built engine over one that is built up that I have to tinker with all the time. This is my daily driver and I live in South Dakota so there really isn't anywhere here to take a custom built 6.0 to for tuning and for sure there is no local dyno. Which is why I keep coming back to the idea of the 8.1 swap.

[jsbihn]

subbed in, looks to be a good one

[guruerror]

I coulda swore that someone on here had done a 8.1 swap YEARS ago...very old thread...I don't think it was with the Allison though.

[jsbihn]

8mph



I would rather 496 my vette, then sell the ls1 and put the maggie I had on my ls1 on my H2.

[Bhplumber]

I have been doing a lot of reading on my swap idea. I keep running into everyone saying just build the 6.0 up some and I should be able hit the 500 hp and 475 trq numbers pretty easy. Build the tranny to handle the power as well. I would much rather have a factory truck rather then a conversion any day but can I really get those numbers and still get factory reliability? My truck HAS to reliable.

I would think a 6 speed Allison would help putting the power to ground but a lot of guys are saying it is a huge tranny which I knew it would require a small body lift to fit but they are also saying it has massive rotating weight. The H2 has enough weight as is.

As much as I REALLY want a 496 H2 it looks like the most idealist way to get more power (high torque #s is really what I want)is just rebuilding my existing drivetrain. I'm not looking to build a race car out of this tank but I do pull about 5K pretty regularly and would like to go up hill without hitting 2nd gear and 4500 rpm all the way to the top.

I haven't totally gave up on the idea yet. PLEASE any input would really be appreciated.

[LoJac963]

You're a prime example of someone who NEEDS a diesel conversion or actually just another vehicle with a diesel.

To expect high torque numbers you're talking high HP obviously. What comes with high HP, lower and lower MPG.

IMO building these up is a complete waste of time and money other than a diesel conversion. But to each their own.