Date: Sun, 2 Apr 2006 17:32:14 +0200
Reply-To: Joy Hecht <jhecht@ALUM.MIT.EDU>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Joy Hecht <jhecht@ALUM.MIT.EDU>
Subject: Re: MPG
In-Reply-To: <001101c65665$78f02ed0$6e00a8c0@owner998c7c609>
Content-Type: text/plain; charset="US-ASCII"
My van definitely has less power at higher elevations, especially before
she's warmed up.
So do I. Even once I'm warmed up.
Do you think the lower air density would make enough difference to balance
out having less O2?
If I go biking at high elevation, like the time I took off on the road along
the south rim of the Grand Canyon, I had to push less air resistance and I
had less O2. The lack of O2 had MUCH more effect on my performance than the
lowered air resistance. In fact, I had to give up and put my bike on the
bus to get back, because I don't think I could have ridden it. The fact
that it had started snowing hard, of course, gave me a perfect excuse so I
didn't have to feel totally wimpy - but clearly lack of O2 was more of an
issue.
On the other hand, a van goes faster and has more wind resistance from its
shape, so maybe the thinner air makes more difference to it than to me on a
bike?
Joy
****************************************************************
Joy Hecht
and Matilda, 1989 Burgundy Vanagon
For musings about life and the vanadventures:
http://www.joyhecht.net
****************************************************************:::-----Orig
inal Message-----
:::From: Vanagon Mailing List [mailto:vanagon@GERRY.VANAGON.COM] On Behalf
:::Of George Thorburn
:::Sent: Sunday, April 02, 2006 4:55 PM
:::To: vanagon@GERRY.VANAGON.COM
:::Subject: Re: MPG
:::
:::Robert wrote,
:::
:::>>At high elevation there is less oxygen so a fuel
:::>>injected engine will compensate with less fuel
:::>>better mileage perhaps but less power.
:::
:::At higher elevations there is also less air to push. The best our '85
:::Westfalia has ever run was two falls ago when we were driving across
:::Montana on I90 and I94 from around the continental divide toward Billings
:::and Glendive. The weather was cool and there was not much wind. I was
:::driving at about 110 kph (4000 rpm) but the van kept creeping up toward
:::120 kph (4400 rpm) I did not check the gas mileage for this particular
:::section but it was no worse than normal. My point is that the van wanted
:::to go faster than normal and seemed to have more power than normal. (It
:::seemed like we had a nice tail wind but we did not.) The only difference
:::I could see was the higher elevation. Higher elevation equals less air
:::density, equals less air resistance for the van to push. As Robert noted
:::the FI system keeps the oxygen to fuel ratio constant at higher
:::elevations.
:::
:::Has anyone else noticed their van running better at higher elevations?
:::
:::George,
:::
:::'85 Westfalia