Paul,
   This probably rates up there with the "Rotary Displacement" question,
   but I'm going to ask anyway.   When you swap out a certified aircraft
   engine for a Rotary, how do you run that panel full of vacuum gauges?
   I've never heard of anyone keeping their air pump on an aircraft
   conversion.  I've always had "all electric" panels in the past, so I
   never really thought about it until now.
   Don


   A few years ago smog pumps were common on car engines. Turns out they
   make great vacuum pumps for powering instruments. A bit heavy however
   but very very cheap in the junkyards.


   Paul Lamar ...No rotor no motor.


Don,
Before I decided to go all electric, I bought an Izusu diesel vacuum
pump.  It is unique in that it couples to an Izusu alternator in which
the shaft protrudes out the back side and drives the pump.  The problem
that I saw was that by the time you got the alternator spinning fast
enough to produce good amperage, you're at the upper limits of the
vacuum pump.  So, as I said, I went all electric and no smog pump was
needed.  Standard vacuum pumps are separate units and probably much more
durable.  Rick (of Blue Mountain Avionics) tried the Izusu setup and the
pump didn't last very long.  But, as I said, the Izusu pump is a
different animal than a normal smog pump.  He may have had it spinning
beyond design limits as well, but that's speculation on my part.

Mark S.
N208TX



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