Reply-To: <glcasey@gte.net>
Reply-To: lancair.list@olsusa.com
From: "Gary Casey" <glcasey@gte.net>
To: <lancair.list@olsusa.com>
Subject: Injector air bleeds
Date: Thu, 7 Feb 2002 19:17:53 -0800
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>>
<<Please excuse my ignorance, but how can air flowing around an injector
affect its fuel flow? Is the air leaking into the injector at the
fitting?? I can see how modifying the baffling would alter the
temperature of the individual cylinders, but why would the fuel flow
change? What do you mean by "high speed air"? Are you blocking off part
of the intake manifold?>>

The injectors have a non-filtered air bleed.  The idea is that the
downstream side of the metering orifice is vented to atmosphere, eliminating
fuel flow effects cause by intake manifold depression.  There is another
orifice downstream of that that uses the air flow to atomize the fuel.  Of
course, this system isn't perfect and there is some restriction to air flow
because of the coarse inlet screen they use.  Consequently, if there is more
"ram" pressure seen at the location of one injector than another the
metering orifice will see a slightly different downstream pressure, changing
the relative fuel flow.  It would seem like a good idea to put a small
deflector ahead of the #2 injector, which is the only one directly exposed
to ram air velocity.  Another approach would be to use "turbo" injectors,
which have a shroud that allows one to manifold the air bleeds together and
connect them to a filtered air source.

Gary Casey
ES project, C177RG


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