[updraught]

[QUOTE=M2M;1856010]Jim, how does gearing affect the equation? For example, a guy comes to you with a car that has 3.27 hi-speed gears, which obviously weakens it's hill climbing ability. In this situation isn't a heavier stock flywheel better than a lightened? Does a heavier flywheel help in pulling hills? If no, tell us why.
/QUOTE]

A heavy fly wheel is like taking a run up to get up the hill.
About half way up the hill the energy runs out as the engine slows down.
You plant the foot. And now you have to fill that heavy flywheel with energy, and find enough energy to accelerate the car up the hill.

Without that heavy flywheel, at the half way point, almost all energy when you plant the foot goes into getting the car up the hill, so it takes off like a rocket. However, with the light flywheel you've had less of a run up at the bottom!