What’s a Hemi and do you need one?

If you turned on the television in the early 2000’s you probably remember all of those Chrysler commercials about having a “Hemi”. And if you’re anything like the rest of us, you probably sat there wondering what the heck a hemi is and whether or not you need one.

A hemi is a type of engine. It is an internal combustion engine whose cylinder’s roofs are of hemispherical shape (hence “hemi”) as opposed to the normal flathead engine. One of the benefits of having a hemi is that the area of the combustion chamber (the part of the engine where the fuel is burned) is smaller than a flathead engine’s. With less surface area, there is less space for fuel to spread out and cool off, ultimately keeping the gas at its optimal combustion temperature and providing for better gas economy. In addition to the smaller surface area, a shape of a hemi allows for larger valve size. Larger valve’s allow for a more fluent control of air and liquid mixtures, allowing for a smoother performance.

All of this sounds really great, but do you need a hemi? Well, not necessarily. Modern technology has allowed for smaller fuel tanks, so there is less worry about fuel not burning at optimal temperature. Additionally, as it turns out, having more valves is more efficient than larger valves. Unfortunately, if more valves were put on a hemi, because of the hemi’s shape they would stick out at crazy angles that would not be efficient for an engine.