Date:         Thu, 11 Jul 2002 15:42:01 +0100
Reply-To:     Clive Smith <clive.harman-smith@NTLWORLD.COM>
Sender:       Vanagon Mailing List <vanagon@gerry.vanagon.com>
From:         Clive Smith <clive.harman-smith@NTLWORLD.COM>
Subject:      Re: drag vs power altitude analysis? Was: water pump advice /
              Murphy's law
Content-Type: text/plain; charset="iso-8859-1"

'...I did notice better gas mileage above 4000 feet. ' - presumably when
running level without hill work; its very difficult to get accurate economy
figures that compare 'like with like' over less than 1000 miles or so -
unless you've an instrument calibrated fuel system. If you are sure, then
this will be thinner air > less resistance, colder temps (slightly upsetting
the former point) > lower inlet temps > better adiabatic compression index
(higher pressure difference between inlet closure and firing for a given
compression ratio (very marginal unless running wickedly hot before).
Is there a general concensus that mpg is better at higher altitudes? - I
doubt  due to hilly nature of terrain. Almost impossible to determine unless
cruising. Another effect might be that the engine is less likely to be
throttled at higher alts, due performance more marginal.

Anyone do a drag vs power/mpg
altitude/density analysis?

It could be done for one particular model config, but there are a lot of
other variables too e.g. static temperatures, tyre pressures, rolling
losses, transmissions and ratios etc etc etc etc. Even then, it would really
only be possible with either VW's engine curves (anyone seen such a thing,
against density and inlet temperature) or masses of empirical data.
If we're talking general trends, I might look into it if enough are
interested.

Clive Smith
'88 Syncro Transporter

----- Original Message -----
From: "Mark Watts" <MVAone@AOL.COM>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Thursday, July 11, 2002 12:55 AM
Subject: drag vs power altitude analysis? Was: water pump advice / Murphy's
law


> Thanks (and to all those who offered their help!),
>
> That is where I got my second pump from as the one I got from carquest was
> BAD!!! Firestone was very gracious about getting us out of there and
picking
> up the other pump. They did charge us for two installs but it wasn't their
> fault. Carquest said they will pay for the install on the bad pump. We'll
> see.
>
> Trip evaluation:
>
> Vinny ran great to Grand Lake through Rocky Mountain National Park
although
> third was used most of the way up and second often above ten thou.  I did
> notice better gas mileage above 4000 feet. Anyone do a drag vs power/mpg
> altitude/density analysis?
>
> thanks,
> Mark and Kelley
> Looking at Grand Lake!
>
>
> >>Rod wrote:
>
> We and our '87 Westy live in Des Moines and always get our work done @=20=
> Jerry's Bug Shoppe=2E  Is that the shop you're referring to or are you
> talking=20=
> about the overpriced place in West Des Moines (What place in West Des
> Moines=20=
> isn't overpriced????)?  Tori & Corey have always been straight forward
> with=20=
> us and do good work=2E =20=
> They also have a back lot full of late 70's and early 80's vans for
parts=2E
> =20=
> They may have what you need=2E  Their number is (515) 282 7940=2E  Their
> almost=20=
> directly east of you on 2nd avenue=2E  Let me know if you'd like anymore
> Des=20=
> Moines info