My question is: Will a 5 foot diameter wheel as opposed to a 4 foot diameter wheel give me more torque because the weight is further away from the axis but slower RPM? I just want to run a car alternator. What pulley sizes do I need to get at least 750 RPM. I have a 14", 11", 4" and 3" pulley's. The alternator has a 2 1/2" pully and I have a counter shaft. My water flow can keep a 2" pipe full all the time. I was thinking of making the water compartments 12" wide & 10" deep on the water wheel.