Re: [DML] Re: catalytic converter question

[Pete Berveiler <zamphyr2000@xxxxxxxxx>]

Increased Octane Ratings decrease predetonation and
increase the detonation temperature in the combustion
chamber by adding longer-chain hydrocarbons and other
"additives" (such as historically Lead and currently
Methyl Tertiary Butyl Ether) that are less
compressive, thus resistant to early detonation and/or
diesel detonation when the combustion chamber is
hotter.

The reason that increased octane rating results in
lower emissions (it does...) is that the higher
temperature spark necessary to detonate the fuel/air
mixture causes a hotter explosion, thus increasing
both power in the stroke of the engine, and fewer
partially-combusted particles (Volatile component of
emissions)...

Low R+M/2 rating gas has more light hydrocarbons than
high R+M/2 rating gas, thus requiring less energy to
break the molecular bond and intitiate the combustion
sequence in the chamber.  In addition, low rated gas
has fewer carbon bonds, thus less potential energy.  

Fuels such as JP-8 (jet propultion fuel used in
fighter aircraft) have incredible potential energy, as
they have very high octane molecule %, requiring a
hotter ignition source (not a problem in jet engines)
and thus a higher efficency...

Pete


--- David Teitelbaum <jtrealty@xxxxxxxxxxx> wrote:
> I understand exactly what you are saying about the
> way the octane
> rating is calculated. It has been my experience that
> going up with the
> octane helps pass emissions testing. It also seems
> to help with fuel
> efficiency but not enough to justify the increase in
> price. I cannot
> give you a scientific reason for it. My guess is
> that the additives
> used to increase the octane make the fuel burn more
> completly. I
> notice I get better gas mileage on a tank of higher
> octane than lower
> octane. I do not say you need to use 91 octane on a
> regular basis but
> it has been my observation that it does lower HC if
> you go with the
> higher octane. These are my observations and
> opinions and everyone is
> allowed to agree or disagree. I say try it, it can't
> hurt. If you
> don't notice any diffference than at least you know
> you are not
> missing anything. Generally if you do fail emmisions
> testing changing
> the octane of the gas you use won't cut it. At least
> it should be
> fresh. If you still fail then you HAVE to find and
> fix the problem.
> David Teitelbaum
> vin 10757
> 
> 
> 
> --- In dmcnews@xxxxxxxxxxxxxxx, "Tom" <tomcio@xxxx>
> wrote:
> > Hello all
> > 
> > This question is IMPORTANT for all DeLorean owners
> even though it is
> > directed to David Teitelbaum.
> > 
> > ----- Original Message ----- 
> > From: "David Teitelbaum" <jtrealty@xxxx>
> > 
> > 
> 
> 
> 
> 
> 
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