A camshaft is an integral part of an engine's valve train system that controls the opening and closing of the intake and exhaust valves. It plays a crucial role in determining the engine's performance and efficiency.
The camshaft is a cylindrical shaft with a series of lobes or cams mounted on it. These lobes are specifically shaped to control the timing and duration of the valve openings. The camshaft is driven by the engine's crankshaft through a timing belt or chain, which ensures synchronized rotation.
As the camshaft rotates, the lobes come in contact with the valve lifters or followers, which are typically made of hydraulic tappets or solid lifters. The lobes push against the lifters, causing them to move up and down. The movement of the lifters, in turn, transfers to the pushrods or rocker arms, which are responsible for actuating the valves.
The shape of the lobes determines the valve timing. The lobes have different profiles, including the base circle, the cam lift, and the flank. When the lobes are not in contact with the lifters, they follow the base circle, and the valves remain closed. As the lobes rotate into contact with the lifters, they push against them, causing the valves to open. The duration and lift of the valve opening are determined by the design of the camshaft.
Once the lobes pass their maximum lift point, the valve springs take over and close the valves, as they return to their seated position. The rotation of the camshaft continues, and the process repeats for each cylinder in the engine.
Why do people upgrade their camshaft?
By altering the shape and arrangement of the lobes on the camshaft, engine designers can control various aspects of engine performance, such as power output, torque characteristics, and fuel efficiency. Camshafts can be designed for specific applications, such as high-performance engines, where the timing and lift of the valves are optimized for maximum power and efficiency.
It's worth noting that modern engines often employ variable valve timing systems (VVT) that can adjust the timing of the camshaft to optimize engine performance under different operating conditions. These systems use various mechanisms, such as hydraulic actuators or phasers, to modify the position of the camshaft relative to the crankshaft, allowing for better control over valve timing.