what is vvti

VVT-i stands for Variable Valve Timing with intelligence, which is an automobile variable valve timing technology developed by Toyota. It was introduced in 1995 with the 2JZ-GE engine found in the JZS155 Toyota Crown and Crown Majesta. VVT-i varies the timing of the intake valves by adjusting the relationship between the camshaft drive and intake camshaft, resulting in improved engine efficiency. Engine oil pressure is applied to an actuator to adjust the camshaft position. Variants of the system, including VVTL-i, Dual VVT-i, VVT-iE, VVT-iW, and Valvematic, have followed. VVTL-i is an enhanced version of VVT-i that can alter valve lift (and duration) as well as valve timing. VVT-iE is a version of Dual VVT-i that uses an electrically operated actuator to adjust and maintain intake camshaft timing, while the exhaust camshaft timing is still controlled using a hydraulic actuator. Toyota says that by optimizing valve timing based on driving conditions, VVT-i increases power, improves fuel economy, and reduces emissions.