[Christ]

Would your engine benefit from a lighter flywheel? Less mass to turn..

Yes, the engine presents the power to turn all four wheels, but it only directly drives two of them, in most cases.

For purposes of acceleration, if you have two heavy wheels and two light wheels, the light ones should be on the drive axle, as this will prevent less necessity of force to turn the wheels.

Since it requires less torque to turn a lighter wheel, it will be dually beneficial to your engine to have light wheels on the drive axle.

Dual benefit:
1. Engine uses less power to accelerate rotating mass

2. The wheels will weigh less overall, therefore there is an overall weight reduction in the vehicle, thus making the engine work less to keep moving the vehicle.

As you can see, the first benefit speaks more to acceleration, the second benefit speaks more to keeping that motion.

If this doesn't do it for you, you'll have to google it or something... this is the best explanation I can think of.