Frans,
Your concern was the first thing I worked on with Jason.
The fuel comes in and is under pressure through the manifold then to the
regulator just like a car. Any air passes through so quickly as it is
the path of least resistance out of the manifold that it is not a
problem unless the tank runs dry...and you don't have another full tank.
That's another problem. For those of you worried about switching
tanks, install a header tank as used to be a common thing. As fuel
injection matured and dumb things like putting the regulator at the pump
was changed, air in the system became less of a problem as witnessed
with our current fuel injected cars and trucks. Once one side runs dry
just like in a diesel truck with two tanks, the pump reprime is quick
and the air bubbles pass quick. A couple of sputters and your off.
Just don't get into that problem on final...Of course that is a pilot
problem. The Riley Rocket Cessna 310 used two fuel injected
Continentals and we would run until the first hickup and scramble to
switch from the aux tanks. If you weren't quick, you were single engine
for about 10 seconds. The fuel pressure was the key. Set the warning
system, (which we didn't have) to alert you of a drop of fuel pressure
---From the manifold and switch tanks. Also, I have learned from the car
guys that you put the filters aft of the pumps to lower the suction
problems.
If you insist on running a tank dry. Do this:
Install a fuel pump on each tank that is low pressure high flow.
Install optional shutoff valves in a header tank to keep the pumps from
running constantly.
Install an overflow on the header with one way check valve back to the
main tank.
Put a pair of high pressure fuel pumps in series with shutoff valves
---From the header tank with inverted pickup in case of turbulence.
Install a header low fuel warning system to alert of impending fuel
exhaustion to warn of tank changing.
Install the SDS system as designed with the regulator after the
injectors with the return back to the header.
See off road racers set ups it is virtually the same.
It just takes time.
Bud
----- Original Message -----
From: Frans Veldman<mailto:frans@paardnatuurlijk.nl>
To: europa-list@matronics.com<mailto:europa-list@matronics.com>
Sent: Wednesday, May 13, 2009 4:27 PM
Subject: Re: Europa-List: 914 Fuel Injected Update & Opinion
<frans@paardnatuurlijk.nl<mailto:frans@paardnatuurlijk.nl>>
Curtis Jaussi wrote:
> Lots of good questions. I can address some of them. Jason is well
aware of
> the problem of potential air in the fuel and has designed the fuel
flow
> through the system and back to the tank so that any air should be
pumped on
> through quite quickly. This part makes sense to me.
Yes, but it is still possible that some air will make it into the
injectors. And then? Furthermore, it doesn't has to be air, it can
also
be vaporized fuel. Although any engine hates that, a fuel injected
engine especially hates it. With the tight and warm Europa cowling,
and
high altitude capability, and the use of Mogas, I think some fuel
vapor
can hardly be avoided.
Also, this system will make it impossible to run a tank dry, before
switching to the reserve side. So, this poses the problem that one has
to decide at what level to switch over. 5 Liters at least remaining
seems to be the minimum to me, and one should not forget to switch
over
in time. (if the reminder is in the form of a sputtering engine, like
it
normally is, it is probably to late for the fuel injection system).
With
5 liters, one has about 10 minutes left (considering the fact that the
very last liter will probably have so much air in it that it will be
unusable anyway). This will cut the usable amount of fuel
considerably.
Any fuel savings due to the fuel injection is offset by the fact that
you can't risk to run the main side of the tank dry, so effectively
you
can't increase the endurance.
> As for redundency, it
> is totally redundant with two complete systems: two fuel pumps, two
sets of
> injectors, two sets of sensors,separate electrical systems, etc.
Only one
> system is in operation at one time and you manually switch from one
to the
> other if needed.
Ok, sounds good.
I think that Jason will probably draw more customers if he puts all
this
kind of information on his website. I could do with less pictures.
Some more information about an upgrade kit for existing 914's would be
great as well.
--
Frans Veldman
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avigator?Europa-List>
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on>
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