valve overlap

[Jim Yeagley]

Yes, you're right!  I should have said "a tighter or smaller lobe seperation
angle."

Thanks!

Jim Yeagley
1996 Dodge Indy Ram
See it and many others at: www.indyram.org
1975 Pontiac Grandville Brougham Conv. (in baskets)
webmaster at indyram.org
jimyeagley at stratos.net


>I'm curious (not being picky). Going by the apparent meaning of the phrase
>'lobe separation', wouldn't greater lobe separation mean less overlap?
>
>Basic is good. Basic answer please.
>
>Gwyn Reedy
>Brandon, Florida
>mailto:mgr at mgrcorp.com
>
> With a normally aspirated (unblown) engine, more valve
>> overlap, or a larger lobe seperation angle, aids mid to upper rpm hp by
>> allowing the outward flowing exhaust gasses to create a sort of vacuum in
>> the combustion chamber when the piston is around tdc and both valves are
>> open, where this vacuum starts to 'pull' the intake charge in before the
>> downward moving piston begins to draw.  At lower rpms, it creates
>> that lopey idle we all know and love, but robs low end torque.
>
>