Flywheel weight reduction?

[Matt Timion]

I'm a bit new to the car scene. Admittedly, I only learn what things do on the car when I'm about to modify them. I had no idea what a throttlebody was when I bought a new one for a project. I had no idea what fuel injectors were until I took a good look at the intake manifold (intake manfold, what's THAT?!?!)

Anyway, I have no idea what a flywheel does.

I do know, however, that it's one of the things the engine spins constantly. Just like the tires, spinning weight is the first thing that needs to be reduced. Even if the weigh reduction is fractional, it will then require the engine to work less to move the same parts, thus enabling you to get lower RPMs at the same speeds, and therefore giving you a much more fuel efficient vehicle.

So how much can you reduce the weight of a flywheel? I will be throwing in a new transmission with my new engine once they all get here. While I'm there I will be throwing in a new clutch and flywheel so that I don't ever have to worry about either of those things going bad on me.

The question is, how much can reducing flywheel weight help? In my situation it will be impossible to test the effects of EVERY modification I make (I'll be making at least a half dozen modifications total, so it's impossible to test for teach variable). Also, how much weight can be removed from the flywheel? I'm assuming they make racing flywheels for this very reason. Is the extra cost of the lighter flywheel worth the potential savings?