The Murphy Builders Site

I recall from past Soob reading some concerns about vapor lock by returning
warm fuel to the header, as opposed to the main tanks (giving it distance and
volume to cool). What's your take on that Ken? Also, when you said that on
further consideration you might just use after-market external pumps, do you
mean that and no header?
-Ben

On 12/31/2005 5:08 AM, klehman@albedo.net wrote to rebel-builders:

That still requires active fuel management though which is still a
frequent cause of "incidents".

If you can find a place to put it, I really like the use of a header
tank with fuel returning to it. No management required and no concern
about injesting air when low on fuel!

I also like returnless EFI which has been on a number of cars such as
the Neon for about 10 years now. Such systems seem more common every
year and don't seem to have any hot start issues. Not sure but I think
the 40 ish psi rail pressure is enough to prevent fuel boiling when the
engine is shutdown.

Ken

One had the stock Sub fuel pumps mounted in the bottom of
the wing tanks, on removeable plates - worked great ! The
return line came up to the roof, with a valve to direct return
flow to left or right tank, to aid in load balancing. Ideally,
the return line is not at the top of the tank, so the fuel
doesn't fall, picking up air & static .... One nice thing
about this is there were no fuel valves needed - just turn on
the pump on the tank you wanted to feed from ! ;-)

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I'd keep the header tank but guys have run headers as small as a liter
(quart) and even put them forward of the firewall with a little heat
shielding without problems. I would run an upsloping vent line back to a
tank or the tank crossvent with any header regardless of size or
location. I don't agree with everything on the SDS efi site but I
believe he documents such an installation there and still uses it. Think
he made the tank out of a 3 or 4" section of aluminum tube. A vertical
oriented tank might even allow some thermosyphoning back to the main
tanks after shutdown, as will any rising vapour bubbles. A small header
is much easier to locate and with external pumps it's light enough that
it is easy to mount securely.

To be honest I don't recall anyone having vapour problems who used a
header. The Eg...... boys had problems when they tried to use a little
cooler on the return and recycle the fuel without a header but I'm sure
I'm not the only one who cautioned against flying that way...

Ken

bransom@dcsol.com wrote:

I recall from past Soob reading some concerns about vapor lock by returning
warm fuel to the header, as opposed to the main tanks (giving it distance and
volume to cool). What's your take on that Ken? Also, when you said that on
further consideration you might just use after-market external pumps, do you
mean that and no header?
-Ben

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