Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Posting-Version: version B 2.10.1 6/24/83; site zehntel.UUCP
Path: utzoo!watmath!clyde!floyd!vax135!houxz!houxm!ihnp4!zehntel!zinfandel!joe
From: joe@zinfandel.UUCP
Newsgroups: net.auto
Subject: Re: Octane ratings, 1973 vs 1984 - (nf)
Message-ID: <1541@zehntel.UUCP>
Date: Tue, 19-Jun-84 04:21:17 EDT
Article-I.D.: zehntel.1541
Posted: Tue Jun 19 04:21:17 1984
Date-Received: Thu, 21-Jun-84 07:13:07 EDT
Sender: root@zehntel.UUCP
Organization: Zehntel Inc., Walnut Creek, CA
Lines: 23

#R:qubix:-119300:zinfandel:3200067:000:979
zinfandel!joe    Jun 14 08:44:00 1984


	Hi. What I know on the subject is that the motor method is
the older of the two systems, and is still used. It involves a standard
single cylinder engine run just hard enough to make the fuel tested
detonate. This level of engine output is compared to the performance
of pure octane, a relatively good performer. For exact percentages
they find the percentage of octane in a mix of octane and pentane 
( a very willing knocker ) that performs as well as the tested fuel.
Fuels of other composition can perform better than pure octane so
"150% octane" gas is possible.
	The other method "rational method" is a sophisticated
chemically based formula for calculating the knocking potential, again
as compared to pure octane.
As the variables involved in knocking are many these are both guides but
not absolute predictors. In practice they are consistant however, and
usually don't vary for the same fuel by more than one or two points.

			Joe "I HEART MY DOG'S HEAD" Weinstein