What is VTEC?
VTEC stands for Variable Valve Timing and Electronic Lift Control, it allows Honda to specify different values when a valve is opened, and how much it is opened depending on a variety of factors. The biggest factor is RPM, in engines with static lift and duration would be restricted to a setup that would let in enough air and fuel at a low RPM would not allow enough air and fuel in at a higher RPM, greatly limiting the engine’s potential performance.
However, if the timing and duration were setup so that enough air and fuel was let in so that the engine would produce a lot of power in the higher revs, the engine would not run smoothly at low RPMs, and would not idle well.
The original VTEC first appeared on the 1989 Integra in Japan. Using a B16A engine it produced 160hp, reaching the “magical” 100 hp per liter mark. In the United States this new technology was first seen in the 1991 NSX, and soon became more available as it became integrated into cars such as the 1992 Integra GS-R.VTEC gave the engine two camshaft profiles, one for efficient smooth reliable low RPM operation, and one for power at high RPM operation. The profiles were switched based on oil pressure and engine speed. Oil pressure increases as RPMs increase, the engine uses this increased oil pressure to push a locking pin, which activates the high RPM cam profile.