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Most of you know that vapor lock is directly caused by low pressure on the
inlet side of fuel pump. There are a number of design oversights that
will increase your risk. Among them is the inlet filter. It causes pressure
drop. As does fuel flow meter, diameter of fuel line, pump temperature, head
pressure, inadequate fuel vent, fuel type, altitude, flight attitude, fuel temp.
This is one of the few design features that truly is complicated. You can't
just follow someone else and assume you are ok. It's the fine details of your
fuel design that makes a difference. YOU CAN'T JUST RUN YOUR PLANE ON THE GROUND
AND ASSUME YOU ARE NOT AT RISK.
I use a large filter bag on one inlet. Nothing on the other inlet. The
large bag is self cleaning, has huge surface area, little pressure drop. It's
used by the auto manufacturer.
Please investigate thoroughly and resist assumptions. Your life depends on
it.
regards
-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
Kevin,
I have know idea why EFI filters cannot be used on the
low pressure side as long as they do not restrict flow. Hopefully someone will
chime in with the facts. I am planning on using EFI filters before my pumps
also. They are the same ones that Ed and others are running on the high
pressure side. They have a large 16mm in and out. AC Delco GF652. I believe
the Egg subi's are also running these filters on the low pressure
side.
Bobby
I suspect that my engine problems stem
from a design flaw, rather than a blockage. I normally never run my
engine full power, full rich, but have been while breaking in the new
rings. even leaning the engine a few notches prevents my problem, so it
never arose in the past. my auto fuel filters are on the "suck" side,
between the tanks and the selector valve. they are small, glass see-thru
mesh filters. I realize now that all the fuel passes thru a pair of like
1/8" holes from a common 1/4" passage. I also see that the facet pump,
despite pumping 15+ gals / hr with no head pressure, will only produce 1.75
lbs pressure when attached to the carb and bypassing the manual
pump.
my question - I was
told not to use a fuel injection filter on a low pressure system like
mine. I would like to keep the filters where they are rather than moving
them to the engine compartment, since they filter stuff ahead of my flow meter
and pumps. I like how they fit along the wing spar below my knees.
I had problems with the replaceable filters shedding fibers into the carb,
which is why I changed to the mesh filters. does anyone know what
I should be using?
I plan to do more
testing this weekend if my wife will let me drive her car("no, I'm not feeling
sleepy :-)" to get to the airport.
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