I am not a chemical engineer, but my understanding is that the amount of
energy in a gallon of gas is the same no matter what the octane.  Higher
octane gas simply burns more slowly.  This is required in higher compression
engines where the gas without octane enhancers would start burning all by
itself before the spark simply from the existing heat and compression.  This
is preignition, knocking, or pinging.

If someone out there has a more accurate description, or if I'm dead wrong
here, please let me know (as I know you will!).

Karl Wolz
----- Original Message -----
From: "Wagner, James W., , SAF/AQPS" <WagnerJW@PENTAGON.AF.MIL>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Friday, February 25, 2000 8:11 AM
Subject: Re: While we are onthe topic....

> Actually, the reverse is true based on an energy analysis.  Higher octane
> gases are made to burn slowly by using additives, thus for a given volume,
> there is less energy. This isn't very noticeable with my Vanagon (I guess
> because it gets poor mileage to begin with and has electronic fuel
> injection), but on my motorcycle, the difference is between about 59mpg
for
> 93 octane versus 67mpg for regular 87 octane gas.
>
> James Wagner
>
>
> > -----Original Message-----
> > From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com]On Behalf
> > Of Joel Walker
> > Sent: Friday, February 25, 2000 12:36 AM
> > To: vanagon@GERRY.VANAGON.COM
> > Subject: Re: While we are onthe topic....
> >
> >
> > > Do we notice a increase in fuel economy when we use higher
> > octane fuel?
> > > A power increase? Any increase? well besides cost obviously.
> > > I use 92 octane 76 fuel consistently, for me it makes a
> > difference, the
> > engine makes more power, smoother too.
>