Re: Induction length

[Simon Favre <simon@domain.elided>]

No, there is always SOME overlap. Engines designed, or set up for high RPM
usage will have more, at the expense of low end torque. I don't know of
any modern, Otto-cycle engines that have 0 overlap between the end of the 
exhaust stroke and the beginning of the intake stroke. It's only a matter of 
degrees (pun intended).

As a somewhat related Italian data point, the race cam in my Fiat 1100
Formula Junior engine has *80* degrees of overlap, 300 degrees of duration,
and 10.7 mm lift. Mind you, this is in a pushrod engine...

The Tipo 159 Alfetta deliberately used more overlap than needed just so they
could dump more Methanol into the motor for cooling. As it was, the valves
were only good for about 4 hours of run time, according to one of its
engineers.

r.m.bies wrote:

>There is another twist -- I believe that when veloce <meant> veloce, the
>intake valves and exhaust valves overlapped, so that the inertia of the
>exhaust leaving aided in drawing-in the intake charge -- for a 1300cc
>engine, the Giulietta veloce could get quite a bit of fuel through (and
>naturally trailed flame at high rpm).  Damn, what a car.

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