Double Overhead Camshafts (DOHC ): Good old Double Overhead Camshafts! This is the stuff to separate the men from the boys.
When a mechanically minded car fanatic feels he's losing ground in an argument or discussion, and that you may know that little bit too much about cars and the way they work, he or she will surely wheel out the old reliable: camshafts.
The crème de la crème, of course, is the double overhead camshaft. Better still, they will go straight for the abbreviated version: DOHC.
So, to break the code, a DOHC engine has two camshafts in each cylinder head. One of the camshafts controls the intake valves and the other controls the exhaust valves.
The camshafts operate the valves directly from on top, thereby eliminating the need for pushrods and rocker arms. This, in turn, means there are fewer parts which, of course, means fewer things to go wrong or break.
It also means fewer parts to move before the real power reaches the wheels. This way the engine builds up RPM more quickly.
DOHC designs are typically high-performance, four-valve per cylinder engines. This type of engine has two intake valves and two exhaust valves and is considered to aid the engine to "breathe" more freely for increased performance.