July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!

VTEC System

The VTEC system changes the cam profile to correspond to the engine speed. It maximizes torque at low engine speed and output at high engine speed.
The low lift cam is used at low engine speeds, and the high lift cam is used at high engine speeds.

Fig 1: Low Speed Valve Timing And High Speed Valve Timing Signal Graph

Courtesy of AMERICAN HONDA MOTOR CO., INC.