Which factor primarily affects valve lift in an engine?

The factor that primarily affects valve lift in an engine is the camshaft design. The camshaft's profile determines the shape and height of the cam lobes, which directly influences how far the valves open (lift) and how quickly they open and close (duration and timing).

Different designs—such as the size and shape of the lobes—will produce varying amounts of lift. For instance, a cam with a higher lift profile allows the valves to open further, enabling more air and fuel to enter the combustion chamber, which can enhance engine performance. Additionally, camshaft design can influence how aggressive or mild the valve movement is, directly impacting engine characteristics such as torque and horsepower at different RPM ranges.

Understanding camshaft design is crucial for tuning engines for specific performance outcomes, as it sets the parameters for valve operation throughout the engine's cycle.

The other factors, while important in the overall functioning of the engine, do not primarily dictate the amount of lift. Camshaft speed relates to the rotational speed of the engine but does not affect the lift unless the design dictates a specific lift pattern at certain speeds. Valvespring tension is essential for returning the valves to their closed position but does not control how much the valves open. Piston speed affects