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Path: utzoo!utcs!mnetor!clewis
From: clewis@mnetor.UUCP (Chris Lewis)
Newsgroups: net.auto
Subject: Re: Gasoline composition.
Message-ID: <2183@mnetor.UUCP>
Date: Mon, 16-Sep-85 10:49:36 EDT
Article-I.D.: mnetor.2183
Posted: Mon Sep 16 10:49:36 1985
Date-Received: Mon, 16-Sep-85 12:20:09 EDT
References: <479@olivee.UUCP>
Reply-To: clewis@mnetor.UUCP (Chris Lewis)
Distribution: net
Organization: Computer X (CANADA) Ltd., Toronto, Ontario, Canada
Lines: 74
Summary: 

In article <479@olivee.UUCP> gnome@olivee.UUCP (Gary Traveis) writes:
>(*)
>
>I'm trying to find a source of information on the chemical
>make-up of standard auto gasoline.
>
>What is it's general composition?

Gasoline is hardly a "pure" substance.  Fresh out of a fractionating
tower it contains traces of almost all of the hydrocarbons there
were in the original crude.  However, they try to avoid the shorter
ones (say CH4 up to C5H12) and the longer ones (say C10H22 and upwards).
The former because it makes the fuel too volatile (dangerous - though 
you do need some volatility to be able to start), and the latter 
because it makes the fuel too "sticky" (not-quite-burned hydrocarbons 
causing various engine deposits).  Plus, all of the various hydrocarbons
exist in all of their isomers too.  Octane ratings compare a gasoline
"average" mixture with pure C8H18.  It's too expensive to create a "pure"
gasoline.

I used to work in a refinery lab.  We had to perform distillations
on the stuff to determine boiling curves, these curves were used to
determine the "base" grade of the gasoline.  You'd be amazed at what goes
into gasoline.  "Light gas" (mixed with "heavy gas" in various
concentrations to make different grades) was so volatile that
it would boil off in your hand.

There are also various traces of things like mercaptans (eg: H2S),
and in leaded gas, tetra-ethyl lead.

>What other mixtures burn the same, except without the crap
>that causes varnish build-up in the carb?

Probably any "sharp-cutoff" gas (eg: only Octane and nothing else).

>What can be used as a substitute?
Just about any "light" pure burnable:

	Propane
	Natural Gas (mostly Methane)
	Alcohol/Gas mixtures (Gasohol)
	Hydrogen
	Butane (though it might freeze in low temperatures)
	Alcohol
	Alcohol and Nitromethane (racing cars and model airplane engines)
	Benzene/Heptane/Septane/ whatever (some of these are quite
	   dangerous (eg: Benzene is a carcinogen))

Propane is quite popular, LNG, Gasohol and Hydrogen stations do exist,
but are relatively rare.  The others are probably too expensive for
ordinary driving.

All a substitute fuel needs is:
	- a relatively high vapor pressure so that a flammable mixture 
	  gets to the spark plugs,
	- a relatively non-poisonous exhaust
	- relatively cheap.

>	How about LP and Propane conversion?

What about 'em?  Other than the fuel tank and replacement of the fuel
injector system they are pretty much the same.  Obviously the engine
needs retuning.

>	(what can happen to high rev engines running them?)

Probably nothing as long as the oil distribution system is adequate.
Ordinary gasolines provide a small amount of lubrication on their own
(because of the bigger hydrocarbons), so the oil distribution system
is probably slightly more critical.
-- 
Chris Lewis,
UUCP: {allegra, linus, ihnp4}!utzoo!mnetor!clewis
BELL: (416)-475-8980 ext. 321


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