Here’s what actually happens when VTEC kicks in
Introduced on motorcycle engines, Honda has been using its VTEC variable valve lift system on cars since 1989. It was first seen in the United States in the Acura NSX in 1991, years before it was spilling forth from the mouths of youth in the heat of the ’90s tuner car craze. With all the hype around the technology, a lot people may be wondering what actually happens when VTEC is working.
The system alternates between normal and high-lift lobes on the same camshaft to optimize engine operation over a wider RPM range. Swapping camshafts isn’t that big a deal to gearheads, although it’s easier on some engines than others, but VTEC allows the engine to swap cams on the fly, at several thousand RPM, and back again. It’s virtually seamless, although the difference in engine performance is noticeable.
This Engineering Explained video shows Honda’s method of using hydraulic pressure from the engine’s oiling system to engage a cam follower and lock it into place with the follower that rides on the lower-lift cam that lifts the valves. It allows for a smooth-idling engine that has good street manners while also allowing for higher efficiency at increased engine speeds that demand more airflow.
So now you know.