What's a Hemi?

What's a Hemi?

What's the big deal with Hemi engines?

To understand the Hemi, it's helpful to understand how engines work. There's good advice on that at the HowStuffWorks website (http://auto.howstuffworks.com/engine.htm and http://auto.howstuffworks.com/hemi.htm).

The Hemi engine was designed by Chrysler in 1951 and launched in a new line of V8 engines that year. Today, it's still the only mainstream manufacturer to use them in passenger cars.

The name was derived from the shape of the cylinder heads, which had a hemispherical design. Since then, we've seen two Hemi engine designs -- one where the combustion chamber is hemispherical, and one where the top of the cylinder head has that shape.

You can learn how a Hemi engine is different from a regular V8 engine at TheHemi.Com (http://www.thehemi.com/intro.php). There's even photos to help you out.

The hemispherical design helps improve thermal and volumetric efficiency when fuel is ignited in the engine's combustion chamber, creating more power without requiring a higher octane fuel to create more compression.

As well, the design places valves across from each other instead of side-by-side, to help improve air intake and exhaust gas flow. Spark plugs also are placed differently, angled to provide maximum ignition combustion in the chambers.

For more information, you can learn about the history of the Hemi at http://victorylibrary.com/mopar/hemi-c.htm.

Finally, you can get Chrysler's take on the explanation by visiting www.daimlerchrysler.com and searching for Hemi.