Originally Posted by vinniekq2
how are camshaft profiles related "directly" to rear gear ratios? An engine doesnt run any different in a boat and their "gearing" is totally different?
They aren't related directly BUT what F'bird is getting at is that with a 26-28" tire size and a 1:1 final trans ratio those rear gears and stall would help put the operating band of the engine closer to where the cam causes it to make most of its power. If you move your power band up then you need steeper gears to make your car run at that RPM.
Changing gears is not totally necessary but in most cases it enables the driver to make the best use of the new found power at the higher RPM ranges.