Matthew Hunt wrote:

> In article <10474lehgvh649b@corp.supernews.com>,
> Al Smith <ecarecar@yahoo.com> wrote:
>
>
>>V-Tec gives an engine two cam shafts - a high speed and low speed cam shaft.
>>Each cam shaft is optimized for its own speed range.
>
>
> No, it gives the engine additional cam *lobes* for high engine speeds.
> There are both SOHC and DOHC varieties of VTEC, and on the DOHC variety,
> there's one shaft for the intake valves, and one for the exhaust valves,
> like a normal DOHC engine. There are low-speed and high-speed lobes on
> each camshaft.

First of all (not for Mr Hunt) - it's VTEC. All caps - no dash.

Second - it's a pretty interesting configuration. For the DOHC
configuration, there are 6 lobes (3 intake and 3 exhaust) per
cylinder. The 3 intake lobes are divided into two small low
RPM lobes, and a single high RPM lobe between the two low RPM
lobes. At lower RPMs, each valve is actuated by its own rocker
arm riding off the two outer lobes. The high-RPM lobe is used
by locking a hydraulically-actuate flap (apparently called the
"follower" by some) that both, rides off the high RPM lobe, and
locks both rocker arms together so that the valves are operated
with the more aggressive cam. The VTEC lobe is a few mm wider
at the fully open end, but the same width at the fully closed end.

The following has a decent diagram:

<http://www.quickhonda.net/howVtecWorks.htm>