1. Variable Timing Control (VTC): VTC allows for the adjustment of the timing of the intake and exhaust valves opening and closing. This is achieved by using an oil-controlled mechanism to adjust the position of the camshaft relative to the crankshaft. By altering the timing of the valve events, VTC optimizes engine performance and fuel efficiency at different engine speeds.
2. Variable Valve Lift (VVL): VVL enables varying the amount of valve lift (how far the valves open) in addition to controlling valve timing. It typically utilizes rocker arms or lifters with variable profiles that change the effective cam profile depending on engine conditions. At low engine speeds, the valve lift is reduced, allowing for better fuel efficiency and smoother engine operation. As the engine speed increases, the valve lift increases to improve power and performance.
The combination of VTC and VVL in VTEC engines results in improved engine efficiency, increased power output, reduced emissions, and better fuel economy across various engine operating conditions. VTEC engines are commonly found in Honda and Acura vehicles and have been widely used since their introduction in the late 1980s.
