Crankey's got got it right, but only by default. Let me explain. A cobra or any car should be thought of in a collective sense, where the parts work together to achieve a goal. With that in mine think of a formula car. Rail rockers,composits, computer adjustable suspensions,telemitry and more all make these cars state of the art. So what does this have to do with cobras?
Cobras are built using a parts orthodoxy that dictates a certain result. A cobra platform using most of the components talked about on this and other boards tends to limit USABLE horsepower to around 600 Hp. To build a cobra using "other" orthodoxys tends to be sacrilege, so the use of exotic parts tends to be a fringe activity.
My stated goal is to go 8.50's in the quarter mile and yet stay streetable. To do this I've had to drop the independent rear end ideas (orthodoxy) for example and rig up my own setup in the rear. The question then becomes, at what point does a creation cease to be a cobra?
It's no question that a big blocks extra torque can be made to handle anything ANY small block can throw at it. The real question is do you want to go there? Were we are now, that 600 Hp number can be had with a smallblock fairly easy and inexpensively. These cars can't handle much more.
crillyiv is right, a 460 iron block is about the same weight of a svt aluminum block though some castings(dependent on year) are sometimes a bit lighter with iron blocks. The big differance is the aluminum block is stronger and can be bored much more, giving you many engine combo's not available with iron blocks.
My vote- Use a smallblock and keep the car as light as possible. The FUN factor goes way up.
cobrashoch-A diehard bigblock guy.
