I'm not a physics guru by any means, and this question has had me wondering for a while now. Some crankshaft companies like Falicon, will actually add weight to a crankshaft because they claim it increases torque and allows you to run a larger tire for drag racing. You can also of course remove weight, which probably makes less wear and tear on bearings, and give you less low RPM torque, but what else I'm not exactly sure. Is there some sort of a forumla to calculate, if your vehicle/static weight is xx you need xx amount of engine inertia weight to carry it?
Theres also another factor, that on something that is rotating, the larger in diameter it is the more leverage it has on whatever is turning it. For example, a 3lb flywheel 8 inches in diameter will be much much harder for the engine to turn then one that is 3lbs and 3inches in diameter. Or at least thats what I've learned so far.
Could someone enlighten me?