Date: Thu, 9 Aug 2001 09:28:52 -0700
Reply-To: "Pedersen, Michael" <MRPEDERS@PACIFICA-PAPERS.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: "Pedersen, Michael" <MRPEDERS@PACIFICA-PAPERS.COM>
Subject: FW: On Fuel Economy - Some Teutonic Observations
Content-Type: text/plain; charset="iso-8859-1"
-----Original Message-----
From: Pedersen, Michael
Sent: Thursday, August 09, 2001 9:28 AM
To: 'FrankGRUN@AOL.COM'
Subject: RE: On Fuel Economy - Some Teutonic Observations
Now Frank, does this really surprise you? As an engineering technologist, I
"get" to read countless engineering reports stating the obvious in many more
words. I think the key to your ATZ reports is that they are submitted to
the German Gov....a mandatory report stating what is already known. Heck, I
got a lot of stuff here on my desk that might interest you, some I even
wrote... bigger pumps pump more water than smaller pumps, burning salty hog
fuel is bad for a boiler, incorrectly tensioned belts eat bearings,
electronic cathodic protection really does work (hee, hee), energy efficient
motors cost less to run... A non-Teutonic observation I have made...my westy
mileage sucks.
This being said, please keep your astute and witty observations coming.
Often, they are the highlight of my e-mail inbox...
> -----Original Message-----
> From: Frank Grunthaner [mailto:FrankGRUN@AOL.COM]
> Sent: Thursday, August 09, 2001 1:16 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: On Fuel Economy - Some Teutonic Observations
>
>
> I was just scanning through some of my Automobiltechnische
> Zeitschrift (ATZ)
> paper copies and came upon the engineering study done by Audi
> engineers in
> the development of the 2.3 liter 5 cylinder gasoline engine
> for the 1987 Audi
> 100. I thought I would share two very interesting data sets
> with the list. At
> issue are the very detailed fuel consumption maps done for
> and submitted to
> the German Government for fuel consumption certification.
>
> Now measuring fuel consumption of and engine on an engine
> dyno is difficult
> enough, valid numbers for a moving vehicle are particularly
> challenging
> (euphemism). Along with the many driveline, road surface and
> ambient issues,
> the car profile, drag coefficient, frontal surface area,
> etc., etc conspire
> against meaningful numbers. So the factory engineers took lots of
> measurements with two variables constant (car and road test cycle).
>
> The first key result is a plot of urban fuel consumption (DIN
> cycle) vs. curb
> weight. There 108 data points, all for the 1987 Audi 100 with
> 10 valve,
> naturally aspirated with catalytic converter and 5 speed
> manual transmission.
> The data shows a linear relationship for curb weights of 750
> kg to 1600 kg.
> The fuel economy went from 8 l/100 km (750 kg) to 16 l/100 km
> (1600 kg).
> Linear. Linear! Twice the mass, half the fuel economy. So
> urban cycle fuel
> economy of Joe Blow's Westy vs. Sara Etheria's Westy will
> depend linearly on
> their respective masses!
>
> Second data set. Part throttle (read cruise) fuel consumption
> numbers for the
> Audi 100 in fifth gear. Up to 60 km/h data shows a near
> constant 6 l/100 km.
> from 60 to 200 km/h the fuel consumption rises exponentially
> to 23.5 l/100 km
> at 200 km/h. So at 70 mph vs 55, the consumption has
> increased by 30 % for 80
> vs 55, the increase is 80 %. This number is a strong function
> of frontal
> surface area, so the difference for the vanagon will be even more. So
> comparing Hubert Schmuk in his fully loaded Westfalia with
> three kids, wife,
> 2 dogs and all the necessary accouterments averaging 80 miles
> per hour on his
> gasoline and water powered 2.1 WBXer probably really gets
> half the mileage
> that Lenny MilqueToast got on his Westfalia carrying wife,
> Perrier Water and
> lots of open space for souvenirs running at 55 mph.
>
> Frank Grunthaner
>
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