What is the transmission limit? hp/tq?

I would love to build up a high HP ls1/ls6. My worry is that I'll destroy transmissions. I know you cannot drop the clutch but with HPDE or autocross where does the transmission give in. I would have the reinforcement plate, LSD, and a cooler in the transmission. I would love to get my hands on an AOR transmission but those seem to be hard to fine. It seems the stock tranmission is the way to go since everything else would require a decent amount of fabrication (audi 016, T56) and a lot of cash(911 transmission). Could I run a lot of horsepower with a light rotating assembly, flywheel, and clutch to reduce the strain from all the momentum? At what hp/tq do people start breaking transmissions? Should I start with a na trans and really practice driving something with high hp and a weak tranny?

bp944 wrote: At what hp/tq do people start breaking transmissions? Should I start with a na trans and really practice driving something with high hp and a weak tranny?

Its all about the driving style really. Ive heard numbers like 400hp as the limit but I think all the tranny carnage is due to a short and high rpm range from the 4 cyclinders' power band. Its a very tremendous and sudden load on the old R&P which has the devils chore taking it all. The V8s however produce a smooth and relatively broad and level power band which in turn doesnt produce such a shock on the drivetrain.

bp944 wrote:Should I start with a na trans and really practice driving something with high hp and a weak tranny?

Absolutely! If you already have an NA box, by all means use it.

Over on the turbo 4 side of things, guys are making 550+ ft-lbs at the flywheel, the stock 951 box is insanely stout as long as it isnt abused and the clutch isnt dropped. Its a tougher transmission than its given credit for.