[AT] Fwd: Re: Test

[Stephen Offiler]

There's a lot of interesting variables that affect fuel economy.  When you
start talking about some real elevation (example, the Mile High City) there
are a couple significant factors in play that most people don't realize.

One is the density of the air.  It's "thinner" at elevation.  This
translates directly into lower aerodynamic drag.  It takes less HP,
therefore less fuel, to move the vehicle at a given speed.

The second factor is pretty obsure but quite signficant.  This is a
characteristic of engines called the Brake Specific Fuel Consumption.

https://en.wikipedia.org/wiki/Brake_specific_fuel_consumption

On engines with a throttled air intake (all gasoline engines in other
words) you get better BSFC values, meaning higher efficiency, when you run
with less intake restriction - wider throttle openings, in other words.
And at elevation, in that thinner air, you need a wider throttle opening to
make the same power relative to sea level.


SO



On Thu, Dec 10, 2015 at 10:24 AM, Dennis Johnson <moscowengnr at outlook.com>
wrote:

> Charlie,
>
> I have noticed similar tendencies. Living in Houston area (just above sea
> level) and driving to Oklahoma, Kansas, or Colorado the elevation change
> does make a difference.
> Both of my vehicles with the mileage indicator displayed there BEST milage
> when leaving Colorado.
>
> Dennis
>
>
> Sent from my iPad
>
> > On Dec 10, 2015, at 9:16 AM, charlie hill <charliehill at embarqmail.com>
> wrote:
> >
> > Well David, if we believe what we learned in physics it should work out
> to
> > be the amount of fuel required to lift the vehicle that many feet as if
> it
> > were
> > going straight up.  But it sure does seem strange that with all the ups
> and
> > downs
> > of a trip there would be a consistently noticeable difference.
> >
> > Charlie
> >
> > -----Original Message-----
> > From: David Bruce
> > Sent: Thursday, December 10, 2015 8:48 AM
> > To: Antique tractor email discussion group
> > Subject: Re: [AT] Fwd: Re: Test
> >
> > Charlie,
> >
> > I find the same when I drive from here (near ATIS Central) to Columbia,
> > SC where my daughter and family live. Going to Columbia I get a couple
> > tenths better gas mileage than when I return. The difference in
> > elevation is from 850 feet to (if I remember correctly) 500 or so.
> > As you know the elevation here can change rather abruptly although not
> > like the NC high mountains.
> >
> > David
> > NW NC
> >
> >> On 12/10/2015 7:34 AM, charlie hill wrote:
> >> I'll buy that Ralph.  Back in the 80's when Lynn and I would go
> >> to see her parents in Hagerstown Md we drove her Dodge Colt.
> >> The elevation here is near sea level as we have discussed and
> >> I guess it's a bit less than 1000' in Hagerstown.   Back then I would
> >> dutifully check the gas mileage on the Colt going and coming.
> >> It always got a couple of tenths better mpg coming back to NC than it
> >> did going up hill to Hagerstown.
> >>
> >> Charlie
> >>
> >> -----Original Message-----
> >> From: Ralph Goff
> >> Sent: Wednesday, December 09, 2015 11:46 PM
> >> To: Antique tractor email discussion group
> >> Subject: Re: [AT] Fwd: Re: Test
> >>
> >>> On 12/9/2015 10:15 PM, charlie hill wrote:
> >>> Ralph, that's 120 feet fall in 52,800 feet of run.
> >>> That's about 2/10 percent grade.  A locomotive will run on
> >>> 3 percent grade!
> >>>
> >>> Charlie
> >> That 120 foot fall was real handy for hauling grain to town. Grossing
> >> 30,000
> >> pounds with only 180 hp I learned to really appreciate the advantage of
> a
> >> mostly downhill run to town.
> >>
> >> Ralph in Sask.
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