VTEC

VTEC (Variable Valve Timing and Lift Electronic Control) is a system developed by Honda to improve the volumetric efficiency of a four-stroke internal combustion engine (i.e. improved economy). The VTEC system uses two camshaft profiles and hydraulically selects between profiles. It was invented by Honda engineer Ikuo Kajitani. It is distinctly different from standard VVT (variable valve timing) which advances the valve timing only and does not change the camshaft profile or valve lift in any way.

Context, and description

Japan levies a tax based on engine displacement, and Japanese auto manufacturers have correspondingly focused their research and development efforts toward improving the performance of their smaller engine designs through means other than displacement increases. One method for increasing performance into a static displacement includes forced induction, as with models such as the Toyota Supra and Nissan 300ZX which used turbocharger applications and the Toyota MR2 which used a supercharger for some model years. Another approach is the rotary engine used in the Mazda RX-7 and RX-8. A third option is to change the cam timing profile, of which Honda VTEC was the first successful commercial design for altering the profile in real-time.