Nissan

I know the sr20 is for the nissan silvia and the ka24 is for a truck but which would be smarter. i think the ka24 can get more horsepower than sr20 after working on it

You probably could get more horsepower out of the ka24 but at what cost? it would be far more cost affective to just go with the det. that motor is already built for turbo and will be able to handle alot more horsepower without alot of internel work, the ka on the other hand would have to be rebuilt from the ground up and it just would be as strong anyway, sr20det = aluminium block, ka24 = cast iron block. but if money is not an object for you then by all means build the ka but i think you would be far happier with the sr20det, although the uniquiness of your car would be far greater with the ka24.