Cars Simplified: Everything Automotive Explained

Hemi Engine Design

A Hemi engine is a standard piston engine design with hemispherical heads. The design was popularized in the 1970s by Chrysler, which developed it originally. The domed area above the piston helped produce more power, but it made flat-head pistons impractical for high compression ratio engine, and the domed-head pistons designed for it were too heavy, which reduced power and would increase vibration levels.