The Hyperlogos

Variable Valve Timing, or VVT, is the act of changing the valve timing, or the points at which the cylinder valves in an engine open and close; it may also involve changing the duration, the amount of time a valve is open, and/or the lift, the distance which the valve rises (and thus the speed at which air enters the engine.) Various systems perform some combination of changing timing, duration, or both. VVT systems may also control lift, or the distance the valve travels. Optimally, you would be able to change all of these values arbitrarily over time, as an engine behaves very differently at high RPMs than it does at idle or while cruising. Variable Valve Timing allows you to vary your valve timing to a certain degree, achieving significantly better efficiency at all speeds.