What does the VTEC system in a Honda engine do?
If you have read How Car Engines Work, you know about the valves that let air into the engine and let exhaust out of the engine. You also know about the camshaft that controls the valves. The camshaft uses rotating lobes that push against the valves to open and close them. Check out How Camshafts Work for more information. It turns out that there is significant relationship between the way the lobes are ground on the camshaft and the way the engine performs in different rpm(rotations per minute) ranges. To understand why this is the case, imagine that we are running an engine extremely slowly — at just 10 or 20 rpm, so it takes the piston seconds to complete a cycle. It would be impossible to actually run a normal engine this slowly, but imagine that we could. We would want to grind the camshaft so that, just as the pi
