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Posted by * on January 3, 2007, 8:50 am
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clare at snyder.on.ca wrote in article
>
> >
> >
> >>
> >>
> >> * wrote:
> >>
> >> > > HLS@nospam.nix wrote:
> >> > > > > >
> >> > > > > > Dont worry about calculating anything. Octane rating has no
> >direct
> >> > > > > > relationship to gas mileage.
> >> > > > > > Antiknock properties are the key.
> >> > > > > >
> >> > > > > and just what do you think Octane rating a measure of?
> >> > > >
> >> > > > The octane rating is, just as I said, a number related to
antiknock
> >> > > > properties.
> >> > >
> >> > > And good anti-knock properties ( higher octane ) allow the
ignition
> >to be
> >> > > advanced which *may* improve engine efficiency. It pretty much
> >invariably
> >> > > improves performance.
> >> > >
> >> > > Graham
> >> >
> >> >
> >> > In the scenario you describe, the improved performance would come
from
> >> > physically advancing the timing - NOT from the fuel switch alone.
> >> >
> >> > You could probably see a similar increase by just advancing the
timing
> >and
> >> > NOT switching fuels - but the engine might suffer.
> >> >
> >> > The simple act of pumping $10 worth of "high test" into the tank of
a
> >car
> >> > that doesn't require it, really does nothing but improve the bottom
> >line at
> >> > corporate headquarters.
> >>
> >> I don't understand your point.
> >>
> >> You can't just advance the timing willy nilly. In any case the ECU
should
> >> control it and any advantage will be gained automatically.
> >>
> >
> >I was thinking pre-computerized ignitions.
> >
> >So, the ECU has been programmed to advance the timing within safe limits
of
> >regular fuel....no more.
> >
> >How do YOU get it to exceed those limits?
> >
> >
> Depends on the ECU. Some can be "chipped" for more advance.Some OBD2
> boxes can be "reflashed" Some that still have a distributor can have
> the timing physically advanced. On some you can adjust the cam sensor
> to provide more advance. On most, it's pretty well "cast in stone"
>
Which, of course, is modifying the car - NOT gaining better mileage by
simply adding high octane gasoline...
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