Just put the tops of the carbs with the floats dangling into a quart can and
run the pump for a given length of time.....you'll know exactly and quick
without a lot of conversation.
----- Original Message -----
From: "William G Rosenbach" <wgrosenbach@juno.com>
To: <mjb@autox.team.net>
Cc: <fot@autox.team.net>
Sent: Tuesday, October 30, 2001 11:54 PM
Subject: Re: Weber Jets
> The pump may be rated for a given flow rate but it should be checked as
> fitted to see how it actually delivers through however many feet of what
> diameter hose, filter, regulator, needle valve, and the like. Check it
> with a nearly empty tank in case the max flow is dependant on head
> pressure. Their might be a bit of a loss from acceleration G forces too.
>
> A few years back, a friend of mine was running a Formula B car on the
> track we had setup on part of the old Stapleton Airport. There were some
> long straights that allowed for long periods of full throttle. The Lotus
> Twin-Cam was fitted with 2 X 45 DCOE's fed by a Facet pump that was rated
> to supply more that the engine should ever be able to consume. Still
> trying to get the jetting ideal, there was an oxygen sensor fitted in the
> exhaust system to monitor the air / fuel ratio by interpreting the
> readout from a digital multi-meter. He discovered that near the end of
> the longest straight the engine lost power and the mixture was going very
> lean. Closer observation of the meter showed that the engine was leaning
> out for the last 1/4 of the straight. The problem was traced to the pump
> not being able to keep the fuel bowls filled for that length of time.
> None of the other tracks permitted the wide open throttle time so the
> severity of the problem might not have been discovered.
>
> Just 'cause it says it pumps X/Hr doesn't mean that's what is getting
> there.
>
> 110 gallons per hour is almost 4 oz per second, if it all gets there it
> should be more than enough, you'd hope! Just as long as there is enough
> there when it's needed.
>
> Bill
> 70 GT-6+
>
> On Tue, 30 Oct 2001 18:12:45 -0700 (MST) Mark J Bradakis
> <mjb@autox.team.net> writes:
> > What kind of volume are we talking about?
> >
> >
> > My Killer Spit, with an internally stock 1500 motor and two 40
> > DCOEs, uses
> > about 4 gallons per hour. It is pretty unlikely you'll be able to
> > find an
> > automotive fuel pump that won't be able to handle that sort of flow.
> > The
> > little Facet electric pump delivers about 12 to 15 gallons per hour,
> > and it
> > is one of the smaller capacity pumps on the market.
> >
> > My guess is that a full race two liter motor might have a capacity
> > for 10
> > to 12 gallons per hour. Hmm, I know there's a rule of thumb
> > relating gallons
> > per hour with horsepower. As I recall, top fuel dragsters have some
> > rather
> > interesting fuel flow requirements, with plumbing that looks more
> > like dryer
> > vent hose than fuel line - they don't need it for long, they just
> > need it all
> > at once!
> >
> > mjb.
>
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