The 1GZ-FE engine uses a Variable intake Valve Timing - intelligent (VVT-i) system to control intake valve opening between 47° BTDC and 13° ATDC and intake valve closing between 3° ABDC and 63° ABDC. These "camshaft add-on's" provide improvements in performance, but are not able to take advantage of all the attributes of a fully variable valve (camless) engine.
With conventional wastegated turbochargers or fixed geometry turbochargers (FGT), a turbine flow area cannot be adjusted during operation.
Knocking is abnormal combustion in which the air-fuel mixture ignites prematurely due to exposure to high temperature and pressure, creating an unwanted high-frequency noise. When the compression ratio is increased, the temperature at compression top dead center (TDC) also rises, increasing the probability of knocking.