The hemispherical head design was revived in 1964. These were the first engines officially designated Hemi, a name Chrysler had trademarked. Chrysler Hemi engines of this generation displaced . Just 11,000 Hemi engines were ultimately produced for consumer sale due to their relatively high cost and the sheer size of the engine bay required to fit it in. The 426 Hemi was nicknamed the "elephant engine" at the time, a reference to its high power, heavy weight and large physical dimensions. Its deck height and bore spacing made it the biggest engine in racing at the time.