SNIP

> > >   I hear what you're sayin', but I really don't think so.  How much
pressure does it take to make hot oil flow through a short length of tube
(or a port in the pump) at a VERY low flow rate?  Very little.  We're
talking a few cc/min; and I'd guess even a couple of psi, would do the job
nicely.  And at 8000 ft we still have; what, about 11 psi.
> > >
> > >
> > >
> > >   As we go to higher altitudes it is probably more likely that we'd
get vapor lock upstream from the fuel pump before we stop getting oil from
the metering pump.
> > >
> > >
> > >
> > >   This is just off the top of my head, so, you know, maybe there is
something I overlooked.  The question is: what phenomenon was Atkins
observing?  He obviously had some reason for his statement.
> > >
> > >
> > >
> > >   Al
> What about the vacuum of the rotors drawing the oil into the chambers?
That happens at any altitude.
> Marc Wiese
>

You are correct, Marc.  However, while the pressure differential created by
the rotors may assist in getting the oil from the "injector" into the
combustion chamber, I am not certain that it would affect the flow of oil
from the Oil pump metering boss into the pump chamber.  The oil metering
pump being a positive_displacement pump is going to pump whatever oil flows
into its chamber.  The issue is whether the drop in ambient pressure at
altitude will cause the oil flow from the front housing boss into the pump
chamber to drop below some critical level.  If the rotor chamber lower
pressure IS "felt" throught the oil injector, its line and the pump chamber
to the pump boss then it would indeed "assist" in the oil flow and
signficicantly reduce or eliminate any "Altitude" effect.

Ed Anderson




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