[Johan]

This horsepower stuff just kills me. 750 hp (the previous poster) knows what he is doing,and has been doing it a long time, but not everyone can handle that much power in such a light car.
Bill Elliott has a Cobra replica (actually a couple ) in his hanger ( I 'm pretty sure one of them belongs to the wrestler Goldberg),and for engines they have Earnie Elliott 358's and jericos for transmissions. Bill took a friend of mine up and down the runway in it and ATE a set of tires in 5 minutes. I declined when it was my turn for a ride, and Bill said "thank Gawd, that thing scares me, 4th is no better than 3rd".
The thing has sat there for three years now with two flat rear tires. I think it is around 780 hp.
The car will really only transmit a certain amount of horsepower to the rear wheels in a tractable fashion, and beyond that point horsepower is not your friend.
I removed my 13.5 to 1 pistons and changed my cam to make my car more street drivable and allow the use of less octane, and have the added benefit of a more durable, longer lasting engine. Cup car motors last a matter of hours between rebuilds, not miles or years.
My opinion is to plop in a nice durable high revving engine of your choice and don't get caught up in the horsepower wars.
500 is a LOT,
It is sort of like breasts, more than a handful is a waste.
A few comparisons:
A Military Humvee has to tote 34.66 lbs per 1 horsepower
Porsche RSR 4.95 lbs /horse
gt40 mkI 4.94 lbs/horse
500 hp Cobra (3200#s) 6.4 lbs /horse
600 hp Cobra 5.3 lbs. / horse
700 hp Cobra 4.57 lbs/ horse
800 hp Cobra 4.0 lbs / horse
Lola Can Am (1575 lbs., 610 horse) 2.58 lbs. / horse
Porsche 917 Can Am (1450 hp, 1650 lbs) 1.14 lbs / horse.

The rear and mid engine cars take the horsepower great because of weight transfer during accelleration. The Cobra does not have any weight back there, except the gas tank, which on some cars was 42 gallons.

I'm not attempting to cut down the guys with high horsepower cars, because they might dragrace them, or be engine gurus, or know what they are doing. I'm just saying be careful.