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Re: fleecing of automobile owners



Dan wrote:
> 
> On Sat, May 01, 1999 at 04:24:37AM -0700, Mike wrote:
> > Does anyone really know what octane is?  I did a exhausted study on
> >  content and quality of gas. You are probably going to be blown away by
> > what I have found! Octane is shit!!! Octane is nothing more than an inhi
> > bitor to keep gas from exploding as violently and straight gas.
> > Thereforewhen you use higher octane you get less explosion resulting in
> > less burn and as a result you get less HP not more...
> 
> You did not take something into consideration. Compression ratio. By
> changing the CR, either by altering the combustion chamber volume or by
> addition of a super/turbo charger, you are increasing the thermodynamic
> efficiency of the combustion process. To do this, you need to use a fuel
> that can resist preignition, a higher octane fuel. The HP gained by a
> more efficient combustion more than offsets the HP lost to a higher
> octane.
> 
> Running high octane in a regular 8:1 CR engine is nothing but a waste of
> money, but high octane in an 11:1 engine, like in my 16v, is necessary to
> extract the maximum horsepower.
> 
> Dan

Maybe, maybe, but remember things in the world are different than
published data from the lab. (Referring to what a given company pushes
on the public vs what they report in the stock holder's pamphlet.) I use
Chevron myself, were I live I have tried a bunch of stuff and most of
those stations have a good quality of gas. Point I'm getting to is that
my car is not a High compression engine but I get better mileage with my
stock advance and spirited driving than with 87 0r 89 octane.

The difference in price between the grades amounts to about $1 a tankful
and the savings in mileage is at least a gallon or more, depending on
conditions. So, for my non-scientific butt dyno way of measuring I'm
doing the best for me. And If I ever get the gumption up I'll tweak the
advance a bit to see where the edge of the envelope is. 

TBerk
the refuter (it was my turn.)

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