"M C" <mcunix@swbell.net> wrote in message
news:106mkgcb8hdi616@corp.supernews.com...
> >
> > Your explanations are very confusing. In this post, you make it
sound as
> if
> > VTEC can change the valve timing continuously. The cam has only two
> > profiles and it switches between the two when the engine deems it
needed.
> > It rides on two for economy and rides on the third one (locking all
three
> > together) for performance. As far as I understand, a non-VTEC
engine
> can't
> > really be adjusted, the profile would have to be ground on the cam.
You
> > make it sound as if adjusting the valves will give you a different
cam
> > profile to adjust the power band.
> >
> > Also, as I understand it, the engine uses different length runners
to help
> > boost torque at low engine speeds and shorter runners to boost the
top
> end.
> > Once the engine reaches a certain speed, the runners are activated
(I
> > believe it's butterfly valves) and the short runners come into play.
> >
> > -Bruce
> >
> >
>
> I knew about VTEC for a long time but never really read about it. I
think it
> is a brilliant design for getting the best of 2 worlds of valve
timing. I do
> wonder a about the reliability issue. More parts means more stuff to
wear
> out and fail. Also, the high RPM lobe actuates double duty for the
other 2
> when it is used. I'm sure honda accounted for this with extra lube if
> needed. Also, most cars don't run at high RPM all the time. Still, I
think
> this is an awsome technology and doubtless increases preformance and
> usability. Does any other maker use similar technology?
>
>
Considering how long this technology has been in use I wonder why Honda
claims it as theirs? The Corliss valves used on old steam engines was a
mechanically controlled variable valve system that varied valve action
based on engine speed, that was in 19th century.