Lightweight Flywheel for the Yaris?

[Callisto]

Originally Posted by pinoypizzaboy

what does a lightweight flyweel do anyways?

It is a matter of rotational mass. Most of what a flywheel does is providing inertia to keep things running in between cylinder firings. With a heavy flywheel, you get smoother operation, because of increased rotational mass carrying more inertia, BUT it takes longer for the engine to run up to speed, and it always has to be doing more work to keep the mass of the flywheel spinning. If you lighten the flywheel, you make it easier for the engine to spin up to speed, but also remove some of the smoothness of operation, especially in cars that are use primarily for street driving. When you let off the power, the engine will drop down in speed faster. This can lead to herky-jerky (a highly technical term ) operation. It is a balancing act when weighting the flywheel, you want it heavy enough to be smooth, but light enough to provide responsive performance.