The archives are full of discussion on fuel octane vs performance.
I will accept correction on any statement I make below.
All fuels of all grades are blended for the specific environment that
they are delivered to.
Fuels sold in major smog prone cities have additives that are not blended
into fuels sold forty miles from the big cities.
These *country fuels* will produce more power and better overall
performance than the *city blends*.
I've also experienced better fuel economy running the *country fuels*.
In addition I've heard a wide variety of reasons that vehicles perform
poorly at high altitudes (in addition to lower compression). Some of
these are:
Partially clogged Catalytic Converters, Ignition degraded from long term
use, Spark coils partially failing at high Rpms, Poorly adjusted AFMs,
Improper Timing, Clogged Injectors, Poorly adjusted valves and failing
fuel pumps and pressure regulators.
If you have a high mileage engine it can be the sole reason for poor
performance.
This link will take you to an altitude vs compression chart.
http://williamwareagency.com/forsale/stanvan/altitude.htm
In recent discussions on windage trays it has been speculated that a
properly built and installed windage tray can give you 5 to 10 additional
horsepower and lower engine temperatures (another subject for later
discussions)

Stan Wilder

On Thu, 11 Jul 2002 23:53:48 -0400 Kim Brennan <KimBrennan@AOL.COM>
writes:
> In a message dated Thu, 11 Jul 2002 11:52:22 AM Eastern Standard
> Time, "Richard A. Jones" <Jones@colorado.edu> writes:
>
> >I'm enjoying the story of your trip, but our gas in Colorado isn't
> >garbage.  The
> >octane is reduced because of the altitude, since the oxygen is
> reduced.
> >I won't
> >comment on our level of civilization.  ;-)
>
> So many have said...but for a transient (such as myself) who is
> intending to be at low altitude within a tankful....
>
> Ah well. Another updated in a moment.
>

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