Why are flywheels constructed of cast iron?

Flywheels are constructed of cast iron primarily because they have a lot of inertia. Inertia is critical for the functioning of a flywheel, as it helps to smooth out the power delivery from the engine to the transmission. When the engine produces power, the flywheel stores this rotational energy, which can then be released to maintain the momentum of the crankshaft and prevent stalling. This characteristic is crucial during gear changes in a manual transmission, as it allows for a more seamless transition and helps maintain engine speed.

The properties of cast iron contribute to this functionality. Cast iron has a relatively high density, which provides the rotational mass needed for effective energy storage. Its durability and ability to withstand high temperatures and pressures also make it suitable for the harsh environment of an engine bay, further enhancing its role in minimizing fluctuations in engine operation.