>"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.

Right. Only useful when driving at highway speed in first gear.