The camshaft is driven by the crankshaft through timing belts, gears or chains.Īn engine requires large amounts of air when operating at high speeds. The timing of the valve opening and closing, relative to the position of the crankshaft, is important.

The cams open ( lift) the valves for a certain amount of time ( duration) during each intake and exhaust cycle. Piston engines normally use valves which are driven by camshafts. An engine equipped with a variable valve timing actuation system is freed from this constraint, allowing performance to be improved over the engine operating range. Without variable valve timing or variable valve lift, the valve timing is the same for all engine speeds and conditions, therefore compromises are necessary. The timing, duration and lift of these valve events has a significant impact on engine performance. The valves within an internal combustion engine are used to control the flow of the intake and exhaust gases into and out of the combustion chamber.

Two-stroke engines use a power valve system to get similar results to VVT. Increasingly strict emissions regulations are causing many automotive manufacturers to use VVT systems. There are many ways in which this can be achieved, ranging from mechanical devices to electro-hydraulic and camless systems. It is increasingly being used in combination with variable valve lift systems. In internal combustion engines, variable valve timing ( VVT) is the process of altering the timing of a valve lift event, and is often used to improve performance, fuel economy or emissions. This engine uses continuously variable timing for the inlet valves

Variable valve timing solenoid cost