Dual Overhead Camshafts
A Dual Overhead Cam (DOHC) engine

The 2004 Lincoln LS V8 engine is a Dual Overhead Cam (DOHC) design.

Car Culture/Getty Images

The last time you went car shopping, you probably had a salesperson tell you the car you're considering had a Dual Overhead Cam engine, or you saw "DOHC" in a car's brochure. But what does that

really mean?

To get the real specifics, you should read How Car Engines Work. But, in short, engines have valves that open and close to let air in and exhaust out. A camshaft, or cam, opens and closes the vales. If you have two cams on your engine, or dual cams, the valves can be open and shut more rapidly, allowing for better performance. This type of engine design first appeared on race cars in the early 1900s, and is still one of the most popular engine designs today, appearing in lots of production cars.

Read the next page to find out how automobile racing can keep your body in shape.