Date: Sun, 20 May 2012 08:31:12 -0700
Reply-To: neil n <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: neil n <musomuso@GMAIL.COM>
Subject: Re: Use Air Cooled Fuel Pressure Regulator on WBX?
In-Reply-To: <4fb89c95.87c0e00a.1db7.66cb@mx.google.com>
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Cool. Thanks David.
My gut told me that there might be some issue with both return lines
pushing fuel into one inlet. But as you suggest, I could measure pressure.
Thanks for explaining.
A brass " T " isn't available at my FLAPS, but it does exist of course and
is what I would've used.
The FPR bracket is easy to bend but maybe only to 45º maximum. Hose routing
to accommodate the single inlet type FPR might be difficult. e.g. I found
that even "just" moving fuel rail hoses to top of intake, and feed/return
hoses over to driver side of firewall presents a challenge. (where will it
chaff, wires nearby etc.) A single inlet FPR, with FPR bracket bent to
max., at best, (in my minds eye) would still put the return hoses at an
awkward angle. The feed hoses to new " T " would need to be curved thus
routing them over parts.
So theoretically possible but hose routing might make the idea moot? I
don't feel like spending more money on a test part but could mock something
up I guess.
Neil.
On Sun, May 20, 2012 at 12:26 AM, David Beierl <dbeierl@attglobal.net>wrote:
> At 02:10 AM 5/20/2012, neil n wrote:
>
>> A " T " would be required at inlet, there would be 2 more hose clamps than
>> with the WBX part, positioning it might be a problem, but other than that,
>> will the part work correctly?
>>
>
> I haven't done it, Neil, but I don't see any likely issues. The AFC fuel
> pump delivery rate is the same, injection pressures same, the venting rate
> back to the tank should be the same or less. The AFC system appears to
> feed at one end of the system and vent at the other; the later ones feed at
> both ends and vent in the middle (or to say another way, feed the two sides
> of the engine in parallel) which gives both sides the same inlet fuel
> temperature. Doing it that way it becomes more convenient to have two
> input nipples on the regulator. The only possible (not likely) issue I see
> with using a tee is turbulence/noise/restriction where the two flows are
> constricted, meet, and abruptly turn 90 degrees at the tee instead of
> feeding into the less constricted turning point inside the regulator.
> Since the fuel pump is a positive-displacement type with excess capacity
> it's not going to cause *it* a problem, and I find it hard to believe it
> would constrict flow enough to cause a problem with pressure regulation.
> If you're anal you could test this by installing a tee in place of the
> existing regulator and measuring pressure at the test tee (not the one you
> installed) while running the pump with a jumper. If you wanted to be even
> more persnickety you could then measure the same pressure downstream
> (toward the tank) of the new tee and subtract it from the other reading to
> get the true max pressure drop across the tee itself at max flow
> conditions. We're talking about half a liter per minute flow rates here
> at 35 psi net pressure drop in the system and gasoline's not very viscous,
> so I really don't see a problem. The tee would have to be fuel and
> temperature safe at pressure, of course, and if the return line somehow got
> pinched it might see over 100 psi. A metal tee would take care of any
> worries there.
>
> Yours,
> David
>
--
Neil n
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