Date: Sat, 1 Apr 2006 20:39:52 -0800
Reply-To: Jake de Villiers <crescentbeachguitar@GMAIL.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Jake de Villiers <crescentbeachguitar@GMAIL.COM>
Subject: Re: MPG
In-Reply-To: <000101c655d7$fca61430$6400a8c0@masterpc>
Content-Type: text/plain; charset=ISO-8859-1
We amused ourselves on the long second gear climbs on our way to Targhee a
few years ago by making that series of calculations Dennis. We went over
several 7000' + passes and if I remember correctly ( the numbers are in the
Owner's Manual) we were down to 53 hp at the top. Sure felt like less! We
took VW at their word and used 82 as the starting point.
On 4/1/06, Dennis Haynes <dhaynes@optonline.net> wrote:
>
> This is a long shot. Better fuel economy at high altitude may be due to
> the fact that you are already on top of the hills and spend more time
> going down. Also, the thinner air provides less wind resistance for the
> vehicle to travel through requiring less power. As for the effect on
> engine efficiency, the O2 sensor does not just measure the amount of O2
> in the exhaust. It actually measures the difference in O2 in the exhaust
> and outside. The goal is a controlled reduction of O2. The reduced air
> charge at altitude lowers the dynamic compression, thus both power and
> efficiency suffer. Each 1,000 feet is a 3% loss.
>
> Dennis
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf
> Of Robert Keezer
> Sent: Saturday, April 01, 2006 3:10 PM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: MPG
>
> Maggie,
>
> At high elevation there is less oxygen so a fuel
> injected engine will compensate with less fuel =
> better mileage perhaps but less power .
> Like in high desert,relatively level, not going
> up mountain grades which demands more fuel.
>
> Most mpg mileage improvement depends on driving
> habits and conditions.
>
> Getting lower MPG at low elevation in the summer
> couls mean a bad sensor , spark plug/wires/cap
> rotor issue as there is more oxygen .
>
> Or you are driving at higher speeds , in wind,
> with increased weight, windows open (more drag),
> roof rack (drag), etc.
>
> In a carbureted engine, an engine runs rich over
> 4,000 feet. I went to Lake Tahoe and stayed there
> a month years ago and my Bug chugged black smoke,
> idled rough and had no power.
>
> I had to change the carburetor main jet to a
> smaller size to decrease the fuel and lean it out
> .
>
> The fuel injected engine does this automatically
> . The oxygen sensor talks to the engine computer
> and tells it how much oxygen is exiting the
> exhaust.
>
> At higher elevation there is less oxygen, so the
> computer will order shorter or less-fuel
> injection times to compensate, as the engine
> computer is programmed to keep the air/fuel ratio
> at a perfect 14:1 under all loads and driving
> conditions, including altitude.
>
> Robert
>
> 1982 Westfalia Golf 2.0
>
>
>
>
>
>
>
>
>
> --- Maggie Dew <wildebus@GMAIL.COM> wrote:
>
> > Regarding mpg issues, there are other factors
> > that affect my mpg. One is
> > that when I'm at higher elevations during the
> > summer, I get between 20-22
> > mpg, and when I'm in the flatlands during
> > winter I get 16-19 mpg. I assume
> > it's an issue of available oxygen. Out here on
> > the plains, the winds can be
> > devastating and my mileage goes way down
> > battling the frequent headwinds.
> >
> > Another interesting thing I have noticed is
> > that when I try to compare my
> > speedometer to the speed on my GPS, I don't
> > always get the same readings.
> > Sometimes when the speedometer reads "60", the
> > GPS will say "63", other
> > times "65". I have 15" wheels. It's difficult
> > to say what my exact mileage
> > or mpg is, but I don't think it matters much
> > what actual numbers you get -
> > as someone said, only in comparison to your own
> > vehicle. So if my own
> > observations tell me I'm losing mpg in similar
> > circumstances, then I start
> > checking to see what's up.
> >
> > Maggie
> > '85 Subaru-Westy "Anne Bonney"
> >
>
>
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--
Jake
1984 Vanagon GL
1986 Westy Weekender "Dixie"
www.crescentbeachguitar.com
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