Cast iron flywheel
Cast iron flywheels are cost-efficient and are widely used in production vehicles.
They are cast from iron, alloyed with a blend of materials. After casting has cooled, surfaces and bolt holes are machined as specification, followed by balancing the flywheel. This kind of flywheel has two selections: cast grey iron and nodular iron.
1. Cast grey iron flywheel
Cast grey iron contains graphite flakes which develop when cooling. These flakes make grey iron have particular gray color when fractured, and they are parts of physical properties of alloy as well. This kind of flywheel can be used as stock replacement or tuning mildly. However, it must not be used for racing, high horsepower, sticky drag radical tires or engines which can up to 6000 RPM.
2. Nodular iron flywheel
Nodular iron is created by alloying process which converts gray iron’s crack-promoting graphite flakes into spheres or nodules. With this transformation, the metal gains superb ductile features, with an advantage beyond gray iron in terms of yield strength, elongation and impact resistance. This kind of flywheel is widely used in more and more models as original equipment, with increase in engine horsepower and operating RPM. Nodular flywheel proves to be a superb and cost-efficient choice for high performance street engine which is limited in use.
Billet steel flywheel
Billet is not concerned with the producing process of final product, yet related with the material.
Billet steel is a material with solid length, which is formed in a blast furnace to get rid of impurities, and subsequently extruded into shape by continuous casting or hot rolling. Billet turns out to be much stronger than iron and is free of stress cracks.
This kind of flywheel is made from blank, which is from bar. Afterwards, it would be machined as specification and balanced. In the last machining step, stress areas are removed form the metal and extra strength is created.
Billet steel flywheel is similar with cast iron one in terms of weight. And low-inertia version is comparable with chromoly one with regard to weight.
If you have a high horsepower vehicle or a truck with heavy loads, or you prefer high performance driving or drag race, billet flywheel may be a superb choice.