Billet Crankshafts. A billet crankshaft is machined from a single piece of bar stock, as opposed to being cast or forged in the general shape of a crankshaft and then machined to finished dimensions. For a low-revving street engine, a cast crankshaft is perfectly adequate; forged cranks are stronger yet and are found in many high performance applications. Nothing, however, can beat the strength, balance and ability to tolerate high RPM of a billet crank; the grain structure of quality bar stock is far superior to that of a casting or even a forging where the metal has literally been beat into shape. Special order.