VVT-i:- VVT-i or Variable Valve Timing with intelligence , is an automobile variable timing technology developed by Toyota . The Toyota VVT-I system replaces the Toyota VVT offered starting the age of 1991 on the 5 valve per cylinder 4A-GE Engine. The VVT system is the 2 stage hydraulically control phasing system. VVT-i, introduced on the Toyota JZ engine in 1996, varies the timing of the intake valve by adjusting the relationship between the camshaft drive (belt or chain) and intake camshaft. Engine oil pressure is applied to an actuator to adjust the camshaft position. Adjustments in the overlap time between the exhaust valve closing and intake valve opening result in improved engine efficiency. i-VTEC:- i-VTEC or ( Intelligence Variable Valve Timing and Lift Electronic Control ) is a system developed b...