Couldn't resist, something I finally know a little about. "Octane" as
used in rating the anti-knock properties of "motor fuel" is based not on
n-octane, an 8 carbon straight chain hydrocarbon, but 2,2,4
trimethylpentane or iso-octane. A fuel that is 100% 2,2,4
trimethylpentane (TMP) has an octane rating of 100, a fuel that is 100%
n-heptane has an octane rating of 0. Consequently a fuel that is 90% TMP
and 10% n-heptane has an octane rating of 90, and a fuel with an
equivalent anti-knock ability is rated 90. Fuels with octane ratings over
100 are based on a projection of some sort. Some aviation and racing
fuels have "octane ratings" in the 120 range, which I believe are
technically referred to as anti-knock ratings.
Larry Elliott, '92, 3.9, 4x4, 5 sp'd, LE
On Tue, 1 Oct 1996, James Babcock wrote:
> Yes. Actually 'octane' is a type of hydrocarbon molecule. Others are
> butane, hexane, and heptane. I don't know each one's exact chemical formula,
> but the names correlate to the number of carbon atoms in the molecule.
>
> 100% pure octane has an octane rating of 100. An octane rating
> of 89 is equivalent to a mixture containing 89% octane. Pretty
> straightforward I guess. I'm sure some of you remember
> octane ratings of 103 or 104 when leaded premium was available.
> Does anyone know how the values over 100 were determined?
>
> -Jim.
> 87 V6 4x4
>
> > Was lead actually used as an octane booster or was it used to lubricate the
> > valves and keep them from overheating? Dave
> >
> > At 06:48 AM 10/1/96 -0500, Dave Clement-LDC009 wrote:
> > >Lead used to be used as an octane increasing additive in gasoline. It is not
> > >used anymore mainly because it will ruin a catylitic convertor. If you use
> > >after market octane boosters make sure that they do not have lead in them.
> > >
> > >Dave Clement
> > >89 4x4 LE
> --
> James A. Babcock, Software Engineer email: james.a.babcock@adn.alcatel.com
> Alcatel Data Networks WWW: http://www.adn.alcatel.com
> Ashburn, Virginia personal web page: http://www.dogwood.com/~jbabcock
> Give blood -- it's a great feeling!!!
>
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