Date: Thu, 28 Oct 1999 20:32:55 -0700
Reply-To: Davidson <wdavidson@THEGRID.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Davidson <wdavidson@THEGRID.NET>
Subject: Re: Mileage at altitude - responses/experiences requested
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Not to mention that most mileage at altitude has two components....
Uphill and Downhill...
It is a no brainer that if you measure your mileage on a downhill stretch
you are going to get high gas mileage. And of course the reverse is true for
uphill.
Now if you have about an equal amount of up hill and down hill you might
expect that the negative effect of gravity on your gas mileage going up hill
would be balanced by the positive effect of gravity on your gas mileage
going down hill. But that is not the case. I expect you will get low gas
mileage figures even if the amount of uphill and down hill is equal... not
only because with less oxygen at altitude you will be running rich, but also
because the gains in downhill mileage will not totally make up for the lost
gas mileage going up hill... that's because you have to use your brakes
going down hill to keep your speed under control.
Bill
90 Westy Syncro
Lake Tahoe
-----Original Message-----
From: John Rodgers <inua@SCOTT.NET>
To: vanagon@GERRY.VANAGON.COM <vanagon@GERRY.VANAGON.COM>
Date: Thursday, October 28, 1999 8:18 PM
Subject: Re: Mileage at altitude - responses/experiences requested
>Ken, that would be correct.
>
>At altitude that air density becomes less and less in relation to the
amount of
>fuel going through the engine, so fuel air mixture goes to the rich side,
you
>get incomplete combustion and a loss of power is the consequence. There may
be
>some automatic mixture adjustment built into the F/I but it is probably
small
>and the limits are reached very quickly if its there at all.
>
>As you may well know, fuel injectiojn systems and some of the big
carburetors
>on piston type Aircraft powerplants have auto-mixture controls, and smaller
>aircraft have manual mixture controls that can be operated from the
cockpit.
>Never saw an automotive vehicle so equipped.
>
>John Rodgers
>
>KENWILFY@AOL.COM wrote:
>
>> I don't know about better mileage but I experienced power loss and rich
>> running going over the Sierra Nevadas a couple summers ago. I think it
was
>> 12,000 ft or maybe a bit more.
>>
>> Ken Wilford
>> http://www.vanagain.com
>> John 3:16
>> Office (856)-765-1583
>> Shop (856)-327-0027
>> Fax (856)-327-2242
>
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