Author: "John Tierney" <tierneyj3@...> Time: Mon Nov 28, 2005 10:24 pm PST Link
I'm finishing up my fuel tanks and want to keep some options open regarding
engines. I understand that some engines, such as the Egg.- Subaru, need to
have a fuel return line incorporated in the tank. Do other fuel injection
systems also require a return line? Would it be needed for two tanks or
only one?
Before I seal up the tank access panel I want to make sure I won't need to
make any future modifications.
John Tierney
Salem, WI
[Non-text portions of this message have been removed]
Author: Simon Paul <scpaul@...> Time: Tue Nov 29, 2005 8:11 am PST Link
What I understood from a local A&P mechanic is that most, if not all,
injected engined need a fuel return line to both tanks. Since I haven't
decided on an engine yet, I made return lines to both tanks, a piece of cake
with the tanks still open and a nightmare if you ever need to retrofit. The
extra parts are easily available from aircraftspruce or any other aviation
parts supplier.
Simon
PH-SCP (reserved)
Wings
----- Original Message -----
From: John Tierney
To: RV7and7A@yahoogroups.com
Sent: Tuesday, November 29, 2005 3:43 AM
Subject: [RV7Yahoo] Fuel Tank Fuel Return Line
I'm finishing up my fuel tanks and want to keep some options open
regarding
engines. I understand that some engines, such as the Egg.- Subaru, need
to
have a fuel return line incorporated in the tank. Do other fuel injection
systems also require a return line? Would it be needed for two tanks or
only one?
Before I seal up the tank access panel I want to make sure I won't need to
make any future modifications.
John Tierney
Salem, WI
[Non-text portions of this message have been removed]
Van's Air Force - World Wide Wing
www.vansaircraft.net
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[Non-text portions of this message have been removed]
Author: Mickey Coggins <mc@...> Time: Tue Nov 29, 2005 8:11 am PST Link
> I'm finishing up my fuel tanks and want to keep some options open regarding
> engines. I understand that some engines, such as the Egg.- Subaru, need to
> have a fuel return line incorporated in the tank. Do other fuel injection
> systems also require a return line? Would it be needed for two tanks or
> only one?
If you choose to install the Eggenfellner engine, then you
will need the return line in each tank. It's really not
a lot of work. You may just want to not seal the tanks
access covers now, just move on to the fuselage, and
finish the tanks later.
Some other FI systems require return lines, but I'm
not aware of any others that require it to go to the
tank.
Here's how I did it, in case you'd like to see a slightly
different method than Eggenfellner recommends.
http://www.rv8.ch/article.php?story=20040704204434728
--
Mickey Coggins
http://www.rv8.ch/
#82007 finishing
Author: "Darwin N. Barrie" <ktlkrn@...> Time: Tue Nov 29, 2005 8:11 am PST Link
The new ECI fuel injection system (won't be out for a while) needs a return
line. Run it to the last bay and keep it high in the tank. If you don't need
it you can plug it off. Robbie Attaway of ECI is installing the new fuel
system on his 6 now. Much harder to install a return line later!!!
Darwin N. Barrie
Chandler AZ
----- Original Message -----
From: "John Tierney" <tierneyj3@...>
To: <RV7and7A@yahoogroups.com>
Sent: Monday, November 28, 2005 8:43 PM
Subject: [RV7Yahoo] Fuel Tank Fuel Return Line
> I'm finishing up my fuel tanks and want to keep some options open
> regarding
> engines. I understand that some engines, such as the Egg.- Subaru, need
> to
> have a fuel return line incorporated in the tank. Do other fuel injection
> systems also require a return line? Would it be needed for two tanks or
> only one?
> Before I seal up the tank access panel I want to make sure I won't need to
> make any future modifications.
> John Tierney
>
> Salem, WI
> [Non-text portions of this message have been removed]
> Van's Air Force - World Wide Wing
> www.vansaircraft.net
> Yahoo! Groups Links
Author: "Hans Teijgeler" <hans@...> Time: Wed Nov 30, 2005 7:24 am PST Link
(I accidentally sent this to John only while it was meant to go to
the list, so here's again - a day late)
John,
Most automotive fuel injection engines indeed need a fuel return
line.
Eggenfellner sends the fuel back to both fuel tanks, using a double
fuel selector by Andair. ($$$$)
There are some problems with this setup though:
Contrary to carburetted engines, there is NO fuel buffer whatsoever.
So if you unport the fuel pickup for more than half a second, your
engine will stop.
Furthermore, air will not always bleed too well from this sytem, so
odds are that you'll have a hard time restarting the engine. In
effect, you'll need to keep several gallons of fuel in the tanks just
to be sure. In essence, this fuel is dead weight (which does NOT
equal VFR reserve!!)
Finally, the high pressure fuel pumps used by an EFI system are lousy
in the fuel sucking department and need a very high supply of fuel
(40 GPH minimum for one pump, 65 GPH for two). This raises the odds
for vapor lock considerably (especially with automotive fuel).
A much better setup would be to make a single two-gallon header tank,
which you can locate behind the seats somewhere (balancing the
heavier engine, so you can keep the two batteries forward of the
firewall and keep the high amp wiring to a minimum). Feed the header
tank with a low pressure facet pump from either wing tank (switched
on and off by a fuel level switch in the header tank). Then place the
EFI fuel pumps either inside the header tank (automotive style) or
right below it. In this case, you don't need any fuel return lines to
your main tanks. Plus you can put the fuel filters in the header tank
feed lines, so that you don't have to have any filters between the
header tank and the fuel pumps, reducing the odds for vapor lock
issues.
Basically, this is how NSI solved the problem, although they mount
the header tank forward of the firewall (which to me is a no-go item.
I don't want several gallons of fuel in an area that has a higher
fire risk). Plus it is heavy enough there as it is without 2 gallons
of fuel
Some Eggenfellner customers have followed the header tank approach
(behind the seats) and report good results.
My advise to you would be not to bother with fuel return lines and
plan for a header tank. The weight penalty of this is in fact nill,
keeping in mind the requirement for enough fuel in the main tanks if
you draw from it directly and the reduced need for thick gauge wires
to the batteries which are no longer needed in the aft fuselage.
You'll save cost in that you no longer need one of these expensive
Andair fuel selectors. Two switches to power the low pressure
transfer pumps is all you'll need for fuel management.
Just my 2 cents...
Hans
(NSI Subaru in a Jodel)
--- In RV7and7A@yahoogroups.com, "John Tierney" <tierneyj3@t...>
wrote:
>
> I'm finishing up my fuel tanks and want to keep some options open
regarding
> engines. I understand that some engines, such as the Egg.- Subaru,
need to
> have a fuel return line incorporated in the tank. Do other fuel
injection
> systems also require a return line? Would it be needed for two
tanks or
> only one?
> Before I seal up the tank access panel I want to make sure I won't
need to
> make any future modifications.
> John Tierney
>
> Salem, WI
> [Non-text portions of this message have been removed]