MCarp22 wrote:
It's all aluminum, so it's a good bit lighter than those ugly lumps of iron from mazda or toyota
I wouldn't be so sure! The 4A-GE is a thin-wall cast iron for the block, and has a simple (light) valvetrain when compared to the SR20....add in the fact that the RWD Toyota T-50 transmission is tiny and lightweight compared to the Nissan 5-speed and the results are surprising.
This page claims 155 kg (340 pounds) for the 4A-G/T50 as fitted to the car, less exhaust manifold, and 183 kg (a smidge over 400 lbs) for the Nissan RWD SR20DE with transmission complete as fitted to the car.
http://www.geocities.com/MotorCity/Garage/8422/4age.htm
Now...I didn't create the above webpage, nor did I weigh both drivetrains, but the numbers seem to be in line with what I have experienced and heard elsewhere. I'd be happy to stand corrected if anyone has better information to share. The factory Toyota exhaust manifold is cast and adds a bit of weight, but that is what headers are for. :D
The Nissan does have availability, aftermarket, and displacement/torque going for it, and could be a good option if you come across one for cheap and can make it fit. I'm not saying the SR20DE is a bad choice, just saying don't assume iron block automatically equals heavy.