It's certainly true that the regulators can get confused by pressure
variations caused by other "regulators", though from the list it looks like
most of the pumps we're using in race cars are centrifugal vs. diaphragm
which removes one regulator from the inventory. That's one reason why
large-bore fuel lines are nice, or some flexible sections, since they tend
to smooth out the pulses. A long time ago I "invented" the use of mercury
manometers to synch carbs on multiple cylinder motorcycle engince. My first
prototype used stiff clear plastic for the connector lines and the mercury
pulsed too much to get a good reading. Switching to surgical rubber tubing
solved the problem.
I certainly wouldn't add a recirc line to these systems--one more thing to
fail and potentially cause a nasty fire. Modern cars use recirc systems
mostly to avoid percolation--vapor lock. The suction side of a fuel
injection pump has to have fuel under pressure and no bubbles or it quits
working and won't reprime. Most fuel systems have an in-tank pump to move
the fuel to the pressure pump. some have only that. My Radical has an
in-fuel cell pump that's very trouble free.
Interesting discussion, but I don't think anyone's going to change stuff as
a result--except maybe some bigger fuel filters and check valves in twin
pump systems.
-----Original Message-----
From: owner-fot@autox.team.net
To: fot@autox.team.net
Sent: 2/26/2004 7:08 AM
Subject: Re: Fuel system information - Spitfiresuz's Summary
I had a really interesting discussion with the head engineer at
Aeromotive,
a manufacturer of fuel system components, including pressure regulators.
I
was talking with him because I have had to replace five or six of those
little chrome jobs, and several of us have had failures with Holleys,
although only after a couple of years. By the way (parenthetically) I
have
watched the fuel pressure gauge as a car has been run up on the chassis
dyno - not recommended by the surgeon general -- and found that a system
with a Holley pump and regulator set at 6 psi drops to 2 psi at 6000
rpm,
for whatever that is worth.
Anyway, I have not been able to find a better regulator. The Aeromotive
guy
explained that all these regulators work the same way -- they have a
diaphragm, a spring, and a screw to adjust pressure on the spring. He
pointed out that in the deadhead system that we use, there are three
regulators -- the float valve in the carb, the pressure regulator, and
the
regulator in the pump. With all these going on and off at various and
unpredictable times, it is a wonder that we get the good results that we
do. Just imagine what's happening if two or three of these go open or
shut
at the same time.
Modern systems use a return system -- that is, a line to the regulator
and
a return line to the cell. The fuel is always flowing through the
regulator
and you set the pressure on the regulator -- his rationalle was that
this
reduces the number of regulators in the circuit and promotes more
controllable flow.
I'm not ready to run another line and put another fitting in the top of
my
fuel cell just yet, feeling that this is overkill. But, at the same
time, I
haven't come up with anything better that will eliminate the puzzling
failure of Holley regulators after a couple of years. I guess I'll just
go
on replacing my Holley every two years. I wonder what the Holley folks
would say about all this.
At 09:31 AM 2/26/04 -0500, elliottd wrote:
>And let us know which preference you are going to use.
>
>Don Elliott
>
>----- Original Message -----
>From: <spitfiresuz@141.com>
>To: <group44tr7@aol.com>; <spitfiresuz@141.com>; <fot@autox.team.net>
>Sent: Thursday, February 26, 2004 8:50 AM
>Subject: Re: Fuel system information - Spitfiresuz's Summary
>
>
> > Thanks for the idea - I will check it out tonight and post results.
(I
> > don't think there was any real consensus, so I didn't look into it
>earlier,
> > but I will certainly make sure.)
> >
> > Thanks!
> > Susan :)
> >
> >
> > Original Message:
> > -----------------
> > From: Group44TR7@aol.com
> > Date: Thu, 26 Feb 2004 08:42:02 EST
> > To: spitfiresuz@141.com, fot@autox.team.net
> > Subject: Re: Fuel system information - Spitfiresuz's Summary
> >
> >
> >
> > Thanks for posting the results.
> >
> > However, inquiring minds want to also know if the higher
performing
> > drivers like Babcock, Drews, Jackson, Mordy, Snook, and Steve (sorry
if I
> > missed
> > anyone) have any similiarity in their selection of fuel systems for
their
> > racecars.
> >
> > What the rest of us are doing might be an indication of what
not to
> > do.
> >
> > Cary
> >
> >
> >
> > --------------------------------------------------------------------
> > mail2web - Check your email from the web at
> > http://mail2web.com/ .
uncle jack
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