why shouldn't 4 or 500 hp be possible? don't forget the 1.5 litre turbo's with well over 1000.

i was watching some tv programme on them the other night about the bmw ones, and they reckoned they used ones that had previously done over 100,000 km on the road before being used in f1. they reckoned that by then all the stresses of the casting process would've worked out and if it wasn't broke by then, it never would. they also reckoned that they used to leave them out in the rain behind the engineering block, and that sometimes the engineers would go outside and piss on them (best thing for bmw's if you ask me).

as karl says, it's just about the money to get a strong enough bottom end, and getting the head to flow enough.