What does the VTEC system do?

Every gasoline engine has valves that work with the camshaft to let air into and out of the engine. Learn how VTEC -- Variable Valve Timing and Lift Electronic Control -- allows engines to adapt their camshafts in this HowStuffWorks podcast.

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Episode Transcript

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(00:27):
I'm Marshall Brain with today's question, what does the v
tech system and a Honda engine do? Every gasoline engine
has valves that let air into the engine and let
exhaust out of the engine. A camshaft controls those valves.
The camshaft uses rotating lobes that push against the valves

(00:47):
to open and close them. It turns out that there
is a significant relationship between the way the lobes are
ground on the camshaft and the way the engine performs
at different speed. For maximum engine performance at low engine speeds,
the valves need to open and close differently than they
do at high engine speeds. If you put in a

(01:08):
good low speed camshaft, it hurts the engines performance at
high speeds, and if you put in a good high
speed camshaft, it hurts the engines performance at low speeds.
And in extreme cases, can make it very hard to
start the engine. V TECH, which stands for variable valve
Timing and Lift Electronic Control, is an electronic and mechanical

(01:32):
system in some Honda engines that allows the engine to
effectively have multiple camshafts. As the engine moves into different
RPM ranges, the engine's computer can activate alternate lobes on
the camshaft and change the cams timing. In this way,
the engine gets the best features of a low speed

(01:53):
and high speed camshaft in the same engine. Several engine
manufacturers are experimenting with system that would allow infinite variability
in valve timing. For example, imagine that each valve had
a big sole annoid on it that could open and
close the valve under computer control, rather than relying on
a camshaft. With this type of system, you would get

(02:15):
maximum engine performance at every RPM range. Something to look
forward to in the future For more on this and
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