Date: Wed, 21 Apr 1999 22:41:46 -0400
Reply-To: Bulley <gmbulley@BULLEY-HEWLETT.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Bulley <gmbulley@BULLEY-HEWLETT.COM>
Subject: Re: gasoline and diesel
Javier-
There is a BIG difference between gasoline, and diesel. I am not a
petrochemical scientist, but I have seen pictures of them, and it isn't
pretty.
Gasoline is a volatile fuel-in common English, that means that it doesn't
take much to make it catch fire. That's why arsonists like it. Diesel is
slow to light, you litterally have to hold a li match directly to it, and
whisper a mystical incantation to get Diesel to catch fire.
From my (limited) understanding, gasoline isn't really a very efficient
combustible, just (somewhat) plentiful, and we have a bunch of machines
that already run on it, so why not keep making them, right? The Law of
Inertia.
Gasoline boils at a low temperature, and evaporates quickly at regular
ambient temperature, creating flammable fumes. The engines that burn
gasoline typically have spark plugs and ignition systems to ignite the
fuel/air mixture, after it has been compressed to a measly100-200 psi.
"Diesel" fuel is actually an oil, Fuel oil #2. It is chemically the same as
home heating oil, and the oil that drives heavy machinery (Caterpillar,
etc.) It is not anywhere near as volatile as gasoline, doesn't evaporate
very well (if at all), any isn't as prone to "flash" fires, like gasoline.
It has much higher "thermal capacity" (I think I have the term correct),
meaning there are far greater btu's in a gallon of Diesel, than in a gallon
of gasoline.
The combustion process in a Diesel motor is far different as well. The
design of a deisel motor uses the heat of compression to ignite a fuel. The
idea originated from Dr. Diesel's motor that would burn coal dust. Many
"diesel" motors today burn mixed fuels, including natural gas, methane, and
vegetable oil.
In most "Diesel" motors, there is no throttle plate, so a full charge of
air is sucked into the cylinder with every stroke. That air is highly
compressed, in the range of 800-1,000 psi; this make the air VERY hot. At
just the correct instant in the stroke, a special fuel pump injects a
precisely metered, fine mist of fuel into a special compartment adjacent to
the combustion space. Only in the newest Diesel motors (TDI) is the fuel
injected directly into the combustion chamber. The diesel fuel burns
efficiently, and transfers more of its Btu's into locomotion, and less into
heat than gasoline engines.
You can put (some) gas into a diesel motor, but only put diesel into the
gas tank of a car you do not love. It won't run on it.
You can learn more about Diesel's and other mechanical devices in my
upcoming book, "All I Need to Know About Volkswagens I Learned on the
Vanagon List" Bantam Books, $22.00.
G. Matthew Bulley
Bulley-Hewlett & Associates
www.bulley-hewlett.com
Cary, NC USA
888.468.4880 tollfree
-----Original Message-----
From: Javier Saenz [SMTP:gordita70@HOTMAIL.COM]
Sent: Wednesday, April 21, 1999 4:27 PM
To: vanagon@GERRY.VANAGON.COM
Subject: gasoline and diesel
<< File: ATT00001.html >> << File: ATT00002.gif >> Hola,
What is the difference between gasoloine and diesel? If I put
diesel into my tank will it get better miles? I have owned my
vanagon since new ('81) and have never had any troubles. With
$2/gallon gasoline it would be nice to use diesel intead.
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