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.

[Bhplumber]

A diesel conversion would be great BUT I don't want to spend 30K. Like I said Im not looking or race car just some grunt to pull my trailer twice a week. I only get about 10 mpg right now so I doubt an 8.1 swap or a built 6.0 is going to change the mpg that much.

I could go buy a diesel truck but I like my H2 and can buy a lot of fuel for what even a high mileage diesel would cost. Not to mention I still have to pay for fuel, insurance, and maintenance on the diesel.

I know some people think the H2 is a terrible vehicle. I have owned Jeeps, diesel trucks, 2 ford raptors, and custom built rock crawlers. None of which could do everything as good as my H2. They all have their place but IMO if you want one vehicle that can take you in the woods, through the snow, over the rocks, tow a trailer to work, and still be comfortable enough with 37" tires to take the wife out for a night on the town you have to have an H2!!!

Just my take on it.

[jsbihn]

Heres my take on it.
I have a Vette and my H2 and from what I understand the engine are extremely similar.
So the questions is if you are just looking for grunt, why not change your gears?
I have a plan to change my gears out to something taller for both the Vette and the H2. Gives it the ability to not run the engine as hard while still pushing it up a hill.

I notice on my 03 H2 any kind of an incline will cause my truck to gun the gas when I am using the cruise. (and i mean any kind... like going over a bridge on the interstate)

So maybe, if you have the funds you can beef up the engine, work the tranny and gears some and that should make you happy.
And if you need more power, I would think a 112 or 122 maggie could help you out and could probably be obtained pretty cheap.

Probably come in alot less then a 8.1, allison, and all the labor and hassle to figure it out

[guruerror]

Ever think about stroking the 364 to a 408? EuroHummer had/has a CRAZY fast deuce...he posted some interesting links to Vortec performance stuff in this thread. I know you're not going for speed...but perhaps some of the info will be helpful.

http://www.elcovaforums.com/forums/s...ht=408+stroker

[HummerJim]

I saw an H2 at the old Lynch Hummer dealership where they had dropped in a Corvette Z06 505 hp LS7 crate motor in a 2006 H2 and they said it was almost a direct bolt in except for a custom oil pan with the electrical harness being the most difficult part. That H2 is still in the owners hands somewhere in St Louis I believe.

[jsbihn]

Well the plus about the stroker, which might be something he is trying to go for, the torque