Re: [Amc-list] Super Long Intake Duration Cam ???

[adh@xxxxxxxxxxxxxxxxx (Sandwich Maker)]

" From: David Crooks <david.crooks@xxxxxxxxxxxx>
" 
" " From: David Crooks <david.crooks@xxxxxxxxxxxx>
" " The relationships between cam timing, duration, and rpm are reasonably
" " well understood, and the cold fact is that there is no one grind
" " that's best for both low rpm and high rpm operation.  That's the whole
" " reason that modern high performance motors are using variable timing
" " on the intake and exhaust cams.   Reduce the compromise, for the best
" " of both ranges...
"  From Andrew Hay
" i wouldn't be surprised if one wouldn't want 2-dimensional control for
" peak efficiency, both speed and throttle as inputs to valve timing.
" narrow timing would be better at less than full throttle at any rpm.
" ________________________________________________________________________
" 
" Actually you are 100% correct, and it is done that way.  In the
" case of the high end BMW's, there's no butterfly valve in the
" air intake any longer.  All throttle control is done by adjusting
" the cam timing and lift, electronically.  Do a little surfing, and
" you'll see that totally camless engines are being developed,
" to allow total and complete flexibility.

glad to know i was on the right track...	;^>

i had the idea more than 30 years ago, when i read a r&t article on
vvt as folks were then experimenting with it.  the two that caught my
eye were the ballistic cam, designed to deliberately throw the valves
into controlled float then catch them, and the axial sliding cam with
tapered lobes.  the ballistic cam is naturally rpm-controlled - the
faster the engine goes, the harder the valves are launched - and was
on an ohc engine where the followers pressed directly on the valves;
no pushrods to come adrift.  the axial cam was also on an ohc as it
happened and also rpm controlled, by a flyball governor.  i'd replace
that with a vac diaphragm, or better yet a hydraulic servo controlled
by vac and powered by oil pressure.

an axial sliding ballistic cam, with both speed and vacuum control of
valve timing, by relatively simple mechanics.  -sounds- like it'd
work...
________________________________________________________________________
Andrew Hay                                  the genius nature
internet rambler                            is to see what all have seen
adh@xxxxxxxxxxxxxxxxx                       and think what none thought
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