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Re: [ST] Octane



Ok Bob you have just got my interest.
 
In our sphere of use I was under the impression that the higher the octane the bigger the bang so the faster we go, BUT only in an engine designed and tuned to be run on such fuel. There is no advantage in the average family car, for instance.
 
E.g. If I run regular unleaded (about 86 - 89 octane in Oz) in my bike there is a noticable drop in performance. If I run premium unleaded, anywhere from 92 - 98 octane depending on the vendor, there is a very noticable pick up in performance.
 
Another interesting fact - A few years back Shell introduced a premium unleaded fuel and branded it "Optimax". If its run in a carburetted bike it will foul the plugs within a about one thousand kilometres. Fuel injected bikes will run on it no problems. No one has been able to find out why and Shell threw their hands in the air and gave up. I guess as a group we dont buy enough of it. Their official recommendation is not to run it in carburreted bikes.
 
Perhaps there is someone on this list that knows more about such things.
 
Brett
Sydney
 
-----Original Message-----
From: Bob Floyd <monobldg@xxxxxxxxxxx>
To: ST@xxxxxxxxxxxxxx
Sent: Wed, 15 Jun 2005 09:06:35 -0700
Subject: [ST] Octane


Alright. I have to vent, and if need be, re-educated.

>From time to time I have seen reference made to "premium", "high octane",
"the good stuff" etc, in connection with pump gas. In some form or other,
this is virtually always in the context, or in some form of, getting the
best performance from your ride. 

This makes ZERO sense to me! I'm no rocket scientist, but I do know that
octane is, in fact, a combustion RETARDER. It is used in race and other high
performance bikes specifically because of that. Higher octane levels allow
tuners to raise compression, set timing right to the edge, and all sorts of
other trick stuff while avoiding the resultant potential byproduct of
pre-ignition. 

Therefore, if you're riding a bike with the normal types of tunes, that is
to say, one that has as much stress on reliability as performance,
pre-ignition is not likely a problem. If you don't experience "pinging"
(pre-ignition) then there is NO PROBLEM running regular gas! In fact, you
may actually be cutting performance. This is because regular should actually
be considered the hotter gas, if you will. If you experience lag when you
barely open the throttle, it could be because you're running premium when
regular would actually work better.

I think the oil companies get enough of our money without throwing it away
on octane. I'd rather spend my pennies on cooler clothes so I can at least
LOOK fast.

Okay, if I'm wrong, educate me.

Bob Floyd
01 RS
65 BMW R50
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