Adjust the amount of air intake (exhaust), and the valve opening time, Angle, to make the air income quantity to achieve the best, improve combustion efficiency.

The advantage of hydraulic continuous variable VVT is fuel-efficient, the rate of power and litre is big, fast response speed, low noise, divided into continuous variable valve timing system (CVVT) and dual variable timing system of exhaust device, high-performance engines generally equipped with the system at present.