Mike,
I've seen several of these cars running at the track with 450-550 hp with no drivetrain reliability issues. Since you made reference to the "Toyota Supra Turbo gearbox ", I assume you mean either the 5 speed R154 out of the MkIII or the V160/V161 6 speed out of the MkIV ('93+)? But which one are you looking at? The V160 is heavier duty, but as expected, it's also a heavier box. If this is the one you're considering, have you made preliminary measurements on this box, as it's quite large and that might present some problems. It's also a pretty noisey gearbox. Lots of rattles--kind of sounds like ball bearings rolling around inside there
. And yes, this is normal for these boxes.
The gear ratios for the V160 (3.82, 2.36, 1.68, 1.31, 1.0, 0.79) look pretty decent for the LS1, as you can see from the gear charts shown here:
http://www.mkiv.com/techarticles/getrag/v161/v161_2.jpg
What rear end are you running, or more specifically, what types of rear end gearset ratios do you have available? Since the spread between first and second is so tall, I think you'll end up with basically a 5 speed with a really short first gear.
Here are some sites that have information about this tranny (and the MkIV's in general), many of which you are probably familiar with:
http://www.mkiv.co.nz/
http://www.mkiv.com/
And here's some technical info on the tranny:
http://www.mkiv.com/techarticles/get...ecs/index.html
I've been considering using it for a future project as well. One nice, though often overlooked feature is the fact that is has a bolt on clutch (ie bell) housing, which the T56 6 speed does not. At least, the early T56's don't, I'm not sure about the newer ones.
As far as the clutch, why not just have your flywheel redrilled for a supra pressure plate and clutch assy? They make everything from stock to triple disk setups for that engine/tranny, so that might be an easier way to go. This is what makes these projects so much fun...the choices (and challenges) are endless
...
Good luck and tell me what you decide. Also, please let me know of any other info you happen across. Thanks Mike.
Mike