Ok, ok, the thumbnail is not meant to be serious in any way!

In part 1 on performance flywheels, I did the math on the performance and horsepower gains of a sport flywheel:    • Performance Boosts from a lightweight...  

This video explores how lightweight flywheels can damage and eventually destroy engines.

Sources:
Subaru Boxer Engine by Ypy31
Boxer Engine Animation by Anynobody
Harmonic Balancer by Christopher Ziemnowicz