Developed by Giovanni Torazza in the late 1960s, the system used hydraulic pressure to vary the fulcrum of the cam followers (US Patent 3,641,988).
In September 1975, General Motors (GM) patented a system intended to vary valve lift.
[citation needed] In 1989, Honda released their Variable Valve Timing and Lift Electronic Control (VTEC) system.
General Motors (GM) introduced Intake Valve Lift Control (IVLC) on the third generation Ecotec engine.
Continuously commanded by engine control unit, the valve rocker arm switches between high-lift and low-lift profiles on the camshaft, actuated by an oil control valve through a two-feed stationary hydraulic lash adjuster, allowing for either 4.0 or 10.5 mm lift.
As of 2017 BMW is the only company which can implement all three Variable Valve Timing, Lift and Intake Manifold in continuous adjustment form on production car.
[6] Nissan introduced its Variable Valve Event and Lift (VVEL) in 2007 as the world's second CVVL system.
Nissan's system is more compact than BMW’s, involving fewer parts and less energy loss, and is therefore more adaptable to high-performance engines.
While conventional camshafts feature fixed rotating lobes, the cam in VVEL swings up and down; this is why it does not need a symmetric profile.
VVEL varies valve lift by the eccentric control shaft inside the rocker arm.
By rotating the eccentric control shaft, the position of rocker arm is shifted, changing the swing angle of cam.
The followers can rotate in relation to the roller member by means of internal gear threads and an electric motor attached to the end of the intermediate shaft.
In this way, Valvematic can vary valve lift by adjusting the angle of the finger followers in relation to the roller bearing member.