the KA isn't soooo bad, but there are much better options out there, I have seen good dynos from turboed KA's.
the S15 motor is a bitch of a swap since not only price, but the speed sensor is in the rear differential I believe, also swapping over AC and PS is somewhat of a pain. Bang for buck you can't really go wrong with a BlackTop S13 motor. RB's have plenty of potential, and are also pricey, way a little more, more fabrication is needed to get them to work, aftermarket parts for them are expensive which is why I don't recommend people to go that route.
My opinion would be if you get an s13 chassis, get a 91-94 and go for the blacktop S13 motor, if you want an s14, or s14.5 then I would go with the S14 blackHumpBack motor.
it all depends on how much you have, what RWHP you want, and what the car is being set up to do.
the S15 motor is a bitch of a swap since not only price, but the speed sensor is in the rear differential I believe, also swapping over AC and PS is somewhat of a pain. Bang for buck you can't really go wrong with a BlackTop S13 motor. RB's have plenty of potential, and are also pricey, way a little more, more fabrication is needed to get them to work, aftermarket parts for them are expensive which is why I don't recommend people to go that route.
My opinion would be if you get an s13 chassis, get a 91-94 and go for the blacktop S13 motor, if you want an s14, or s14.5 then I would go with the S14 blackHumpBack motor.
it all depends on how much you have, what RWHP you want, and what the car is being set up to do.