If you have read the article How Car Engines Work, you know about the valves that let the air/fuel mixture into the engine and the exhaust out of the engine. The camshaft uses lobes (called cams) that push against the valves to open them as the camshaft rotates; springs on the valves return them to their closed position. This is a critical job, and can have a great impact on an engine's performance at different speeds. On the next page of this article you can see the animation we built to really show you the difference between a performance camshaft and a standard one.

The camshaft
(click on image to see animation)

In this edition of HowStuffWorks, you will learn how the camshaft affects engine performance. We've got some great animations that show you how different engine layouts, like single overhead cam (SOHC) and double overhead cam (DOHC), really work. And then we'll go over a few of the neat ways that some cars adjust the camshaft so that it can handle different engine speeds more efficiently!