bhp vs torque

I have just bought a new clutch ( competition clutch ) and it says 390 torque? whats that in bhp???

Well thats a tricky one because you can get just as much torque as bhp ... but assuming we get around 30 - 35 % powertrain loss or something like that would work out 500bhp ... someone else may be able to help more ...

What clutch did you buy ???

As above what exact clutch is it ?
That's the thing it is not a bhp figure torque can be lower or higher than bhp depending on many different factors of the engine and set up
What is your spec turbo etc or plans for the car ?
Don't get to hung up I have had less rated clutches last longer than higher depends on driving style aswell

That's exactly right, driving style can have a lot of impact, treat the clutch like a toilet after a all nighter and it's not going to last long

toque rating is what important and that what kills a clutch.
The rating stated is handling rating at fly so on average R build that clutch around the 380 to 430 hp and probably bit over if not thrashing it to the max . 4wd and R's potential rapid power delivery works the clutches hard so always good match with bit of power handling reserve (CC ratings are based on 2wd sr20 applications) and use sprung friction plates unless specifically built box for aggressive solid plate usage or you happy handle potential problems on more standard boxes .
Need take time research and buy wise clutch package for usage even if means mixing lighter sprung covers with paddle plates to give desired durability but sensible pedal load .
CC clutches are pretty good but be careful of the heavy sprung ones, quite lot of info on CC from few users on here in various clutch threads .