What is a Honda vtec engine?

Answer 1

VTEC stands for variable valve timing and electronic lift control. What this means is that when a VTEC engine is operating at higher RPM's, the camshaft makes an adjustemnt that allows the valves to open and close at slightly different times, permitting the engine to breathe better. What this means is increased power at the top end. VTEC usually truns on at about 4500 RPM's. You will likely hear the engine get slightly louder and feel an increase in power. The transition is extremely smooth. It only operates when the car is being driven, not when it's being revved while stopped. The feature is usually present on mid and high level Honda's and on all Acura's.

Answer 2

VTEC stands for Variable Valve Timing and Lift Electronic Control. It was developed by Honda to improve the volumetric efficiency of a 4 stroke internal combustion engine. The VTEC system uses two camshaft profiles and hydraulically selects between profiles. The VTEC system provides the engine with multiple cam lobe profiles optimized for both low and high RPM operations. In basic form, the single barring shaft-lock of a conventional engine is replaced with two profiles: one optimized for low-RPM stability and fuel efficiency, and the other designed to maximize high-RPM power output. The switching operation between the two cam lobes is controlled by the ECU which takes account of engine oil pressure, engine temperature, vehicle speed, engine speed and throttle position. Using these inputs, the ECU is programmed to switch from the low lift to the high lift cam lobes when the conditions mean that engine output will be improved. At the switch point a solenoid is actuated which allows oil pressure from a spool valve to operate a locking pin which binds the high RPM cam follower to the low RPM ones. From this point on, the valves open and close according to the high-lift profile, which opens the valve further and for a longer time. The switch-over point is variable, between a minimum and maximum point, and is determined by engine load. The switch-down back from high to low RPM cams is set to occur at a lower engine speed than the switch-up to avoid a situation in which the engine is asked to operate continuously at or around the switch-over point.