what does a camshaft do for a car and does it increase horsepower and what is the does a crankshaft do ? The reason I asking is because in my civic I'm going to put a gsr in it with forged rods, pistons, jet chip, header, flywheel, clutch, and fuel rail. I already have intake and exhaust but I wanted to know should I get a camshaft cause I'm going turbo in the summer and I wanted to know should you re - sleeve if your going to spray nos and turbo or not?