Max Boost- The Evolution of the Camshaft
The purpose of the camshaft is to allow the air and fuel mixture into the combustion chamber for power to be created. They are also known as cams or bump sticks.
Camshaft
Depending on the manufacturer and engine design, most of the time you’ll find the camshafts very near to the valves. Either the valves and the camshafts are connected by devices called rocker arms or the camshafts sit on the valves. Whenever you start your engine, the camshafts spin in harmony with the rest of the engine in a sequence referred to as timing. The valves allow the air/fuel mixture into the engine and the camshafts determine how fast, how long and how deep the valves open.
The camshafts sitting on the valves
There are irregular shapes along the body of a camshaft called lobes. These lobes are responsible for pushing the valves down to allow the air/fuel mixture into the combustion area. Springs around the valve referred to as valve springs, pull the valves back up into position every time the camshaft’s rotation is completed.
A camshaft with the rockerarm arrangement
Some manufacturers use Single Over Head Cam (SOHC) arrangements, where one camshaft works for both the intake and exhaust valves. Mercedes Benz is one manufacturer that continues to use SOHC arrangements on many vehicles despite arguments for the newer Double Over Head Cams (DOHC), are more efficient. In DOHC, one camshaft works for the intake valves and another separate camshaft works for the exhaust valves.
Camshafts have a significant impact on the feel and performance of an engine; at this point we must discuss the lift and duration of the camshaft. In basic terms, the more lift your camshaft has, the deeper the valve will open allowing more air and fuel into the combustion area. The more duration your camshaft has, the longer the valve will remain open also allowing more air and fuel into the combustion area. The more air and fuel allowed into your engine means that more power will be generated. However if you have too much lift and duration, it reduces the efficiency of the engine at lower rpm, so the larger your camshaft is with regards to increases in lift and duration the rougher the engine response will be at lower engine speeds. Engines with larger than standard camshafts, often have a notably different tone when idling.
Performance Camshafts installed into a SR20DE engine
Increasing camshaft size is a very popular topic when it comes to modifications. However there are many people who want to modify their daily driven machines to generate more power, but don’t want to be subjected to the rough driving and idling at lower speeds of everyday driving. This problem was solved with the introduction of variable valve technology. This allows drivers to have their cake and eat it too. With variable valve technology, the camshaft essentially has two sets of lobes for each valve instead of one lobe, this allows for the car to ride smoothly at lower rpm and to make significantly more power at higher rpm. Providing an engine versatile enough to handle both highway driving and idling in traffic.
Max Boost!!! is a weekly column written by Dwayne Browne
For over 10 years, Dwayne Browne has gained a wealth of knowledge in engine modifications and performance enhancements, through his many project car experiences.
