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

[Ken Ames <ameskg@xxxxxxxxx>]

 hydraulic servo controlled
> by vac and powered by oil pressure.

Trouble with that might be the oil pressure at a particular rpm and how it
changes with oil temperature. Could be a way around that though.

Ken 


Quoting "(Sandwich Maker)" <adh@xxxxxxxxxxxxxxxxx>:

> 
> " 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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