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Hi
Ed;
I'm sending the details of this online as Charlie had asked previously as
well and the benefit of others.
The boost pumps are
Facet 40108 which pump up to the Hi-press EFI pumps which if I remember
correctly are Ford. Basically they are the same as the ones Tracy sells. The
cooler is 3"x3"x3/4" and I made it myself due to an inability to find anything
off-the-shelf. The fuel regulator is an SX performance 15404 and is located on
the cool side of the firewall. All of the fuel line located in the engine
compartment is Parker Hi-Temp push-lok hose. I used hose for it's low thermal
conductivity. The fuel rail is steel rather than aluminium again for it's lower
thermal conductivity. I located the fuel regulator downstream of the fuel cooler
to ensure that the fuel remains pressurized and therefore less likely to
vaporize before the cooler as the liquid fuel will reject more heat than
vaporized fuel.
During T/O & landing, I have at least one boost pump on, but in
cruise I only have a single Hi-press EFI pump on. This system has worked near
perfect for 30 hours of flight. I've noticed that due to my leading edges(tanks)
being painted dark blue, my fuel temps will often be in the high 90's when I
arrive at the airport late in the (sunny) day, during run-up and taxi it
will often reach 110F+, but as soon as I get airborne the fuel temp will begin
to fall. I did have a little problem with the aluminium feed lines between the
boost pumps and the FW where they were in close proximity to the SS muffler
housing. On extended climbs up to 10K the muffler housing became too damn hot
from radiant heat under high power. I lowered the muffler within this housing 1"
and installed an .020 AL heat shield inside the housing, then put an extra piece
of firewall insulation on top of the housing between the fuel lines. Before this
I had one instance where I had a fuel pressure surge due to vapour, but
switching on a single boost pump eliminated it entirely, then a couple of
minutes running at reduced power and I was able to switch off the boost pump.
Since I shielded the muffler housing, I've had no fuel issues at
all.
This isn't a true returnless system as found in late model vehicles as
that would require a high pressure pump with regulator built into each tank, but
it is as close as I could come and so far has been working
great.
What I found very surprising was that air in the system seems to pose no
problem at all. I installed optical fuel sensors Located in "T"s just down
stream of the selector valves and upstream of the boost pump. When I run a tank
dry, the sensor will detect air in the line and flash a big orange light on the
panel. I then have about 20 seconds at cruise power of fuel left before the
engine dies. I can switch tanks before this and the engine never skips a beat,
which surprises me as that air has to pass through the injectors to escape, but
it seems to have absolutely no effect on the engine. Even if I let it die before
I switch the valve, ensuring that the fuel rail is completely full of air, it
still starts immediately when I switch tanks with boost pump on. (proven by
extensive ground test as well as at 10K+) This allows me to completely drain my
auxiliary tanks before switching.
In a related issue. When I originally installed my muffler I cut off the
pipe ~1/2" inside of the exit hole from the housing in a crude attempt at some
possible augmentation. I never really believed that it made much difference,
however when I lowered the muffler 1", the tailpipe was now sticking out 1/2"
from the hole and on the very next flight I was seeing ~15F higher temps on both
coolant and oil. I then cut 1" off the pipe and temps went back down! So I
decided that if I actually made an effort to build a proper ejector I might see
substantial results. Well I built one that is still somewhat crude but was easy
to make and is light, but I haven't seen any noticeable effect yet. I'll try to
do some further work in this area. What I really need to do is make a water
manometer board and do some pressure testing in various locations with &
without augmentation. Sounds like allot of work... I think I'll just enjoy
flying for awhile yet :-)
Todd Bartrim (Still no Kid... might have to go in
& get him!)
RV9Endurance
13B Turbo Rotary
C-FSTB
"The world will always have a place for those that bring hard work and
determination to the things they do."
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