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To: flyrotary@lancaironline.net
Date: Tue, 21 Jun 2005 12:50:55 -0700
Subject: Re: [FlyRotary] EFI return fuel testing
Message-ID: <20050621.125546.2344.4.alwick@juno.com>
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From: al p wick <alwick@juno.com>

I did web queries, couldn't find anything that is friendly enough and
fuel specific.

 So I've put such testing on my list of future activities. I'd like to
experiment with all the various factors, then come up with some sort of
interactive spreadsheet that allows you to do "what if" and predicts your
safety margin. I was hoping to come up with multiple simple ways to
predict. So the guy that doesn't have pressure sensor can still get
measure of safety margin.

Would be nice if someone volunteered to do spreadsheet ...that will be
the tough part. I won't get around to it for a couple months. Too busy
right now.


-al wick
Artificial intelligence in cockpit, Cozy IV powered by stock Subaru 2.5
N9032U 200+ hours on engine/airframe from Portland, Oregon
Prop construct, Subaru install, Risk assessment, Glass panel design info:
http://www.maddyhome.com/canardpages/pages/alwick/index.html


On Tue, 21 Jun 2005 04:58:49 -0700 (PDT) George Graham <rx7ez@yahoo.com>
writes:
> 
> While running my ground testing, during the winters using auto
> fuel.  I used clear 3/8" tubing for fuel line, from my Facet
> pump up to my carburetor.
> 
> While the engine was producing power, I noticed bubbles in the
> line, on the pressure side.  Baffeled by how air could be
> leaking
> into a six psi line, I looked it over, and discovered that there
> was a slight kink in the tubing.  The bubbles were from the
> small restriction in the pressure line (come to think of it, it
> may have been a three psi pump, not six).
> 
> Anyway, the bubbles really don't bother the Carter carb, with
> a float, but, I wonder how much vapor bubbles are returned 
> from the EFI pressure regulator.  It seems likely, that with
> a 35 psi pressure drop, the vapor may be very significant.
> 
> Certainly, someone on this list must have a setup capable of
> testing the theory.  All one would need would be a clear vessel
> to return the fuel to, and perhaps suck fuel out of, with the
> remaining system intact.  Pump on, engine off would seem the
> worst case.  Cold weather auto fuel would be the most likely
> to vaporize.
> 
> Test results could contribute to safe fuel system design.
> 
> 
> 
> George Graham
> Mazda Rx7ez N4449E
> Homepage <http://bfn.org/~ca266>
> 
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