Hemi Engines

A hemi engine refers to the way the pistons, heads and block are designed. This style of engine claims to provide a better flow of air inside the cylinder by creating more room for larger valves in turn providing more power. The chamber on a hemi is hemispherical instead of being flat like traditional engines. This shape provides more surface area on the block allowing room for the larger valves. When the engine can breath better there is less friction and more clean air / fuel mixture providing more power. However, this chamber is very tall so the pistons must be domed to provide adequate compression. While the engine provides larger valves, the new design of the piston actually interferes with the air flow. With the domed pistons it is less likely to evenly distribute the air / fuel mixture, and to adequately remove the exhaust. Lookin at the diagram below, the curved head is easy to see.