I love those hemi dodge truck commercials, but I never really new what the 'hemi' did. My guess was something in the engine that made the truck faster or added pulling power. Well I finally decided to look this one up on "How stuff works."

Short version:
- Hemi is a type of internal combustion engine.
- Hemi gets its name from its hemispherical combustion chamber
- Hemi is famous as a racing engine