Date: Sun, 25 Nov 2007 09:21:19 -0800
Reply-To: neil N <musomuso@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: neil N <musomuso@GMAIL.COM>
Subject: Re: Calculate fuel consumption when idling?
In-Reply-To: <4749A2ED.20405@gmail.com>
Content-Type: text/plain; charset=ISO-8859-1
Hey Mike.
I never took auto shop either. And lookit me know! Using a compression
tester! Rippin parts vans to pieces!
Woohoo!
And didn't you replace your water pump recently?
Neil.
On 11/25/07, Michael Elliott <camping.elliott@gmail.com> wrote:
>
> I somehow suspect you're messing with me here. But I'll bite: the ECU
> works to keep the O2 sensor happy, which means that the mixture is close
> to stoichiometric, meaning roughly 1:15 fuel to air mass ratio; and the
> duty cycle needed to accomplish this is irrelevant. The bottom line is
> that for every gram of air, we use one-fifteenth that in fuel. Roughly. If
> I even have a clue. I never took auto shop. Those were the tough guys,
> tattooed, smoking cigarettes behind the building, greasy fingernails.
> Liked to beat up on little guys like me.
>
> --
> Mike "Rocket J Squirrel" Elliott
> 71 Type 2: the Wonderbus
> 84 Westfalia: Mellow Yellow ("The Electrical Banana")
> 74 Utility Trailer. Ladybug Trailer, Inc., San Juan Capistrano
> KG6RCR
>
>
>
> On 11/25/2007 8:19 AM John Bange wrote:
>
> > I don't think you've spent quite enough time on this. You need to tell
> > us what the duty cycle of the injectors is at idle now.
> >
> >
> > Each piston will still suck in 475 cc of air/fuel per intake cycle.
> But
> > instead of the air being at normal atmospheric pressure, it sucks on
> the
> > intake manifold/plenum, which is at around 11'' Hg of vacuum, or
> > 11'' Hg
> > less than the outside air pressure (Bentley's does not come right
> > out and
> > say that 11'' Hg is the normal vacuum inside the plenum but it can
> be
> > inferred from from several of their measurement procedures). Mean
> sea
> > level pressure is about 30'' Hg, so the plenum contains 19'' Hg of
> > pressure, which is about the same as being at 12,000 feet elevation
> > according to the online Density Altitude Calculator at
> > http://wahiduddin.net/calc/calc_da.htm -- if I'm using it right.
> 70F,
> > 30''Hg altimeter setting, 40F dew point.
> >
> > Under these conditions, air density is 62% of sea level air. So my
> > Junior
> > Engineer's cocktail napkin result of 1.6 gallons per hour of fuel
> > consumption when idling (below) needs to be reduced to 1 gallon per
> > hour.
> >
> >
> > --
> > John Bange
> > '90 Vanagon - "Geldsauger"
>
--
Neil Nicholson. 1981 Air Cooled Westfalia -
"Jaco" (Bustorius) http://web.mac.com/tubaneil
Engine swap beginings: http://musomuso.googlepages.com/home
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