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Unread 10-08-2006, 07:32 PM   #1
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Default Higher Octane = More power ?!?

This is a huge mythe that many people fall victim to. I hear tons of people saying " ya i buy 93 because it gives me a little more power". This is not true, and ill explain why.

Octane is an additive that helps control volitility. Very low octane gas, such as 20-30 octane gasoline, is almost explosive. Octane is added to lower its flash point, and to help control its burning inside the engine so it burns slightly slower, and doesnt act like a rapid explosion. Octane ratings for cars engines is helped determined by compression ratios of the engine. Low compression engines can run just fine on lower octane fuels. Higher compression cannot run on low octane fuels because when gasses, or anything for that matter becomes compressed it heats up. this heating is enough that in a high compression engine low octane fuels will just prematurely ignite, causing the combustion to happen before the piston is at top dead center (TDC). This is referred to as premature ignition. So higher compression engines, which are typically higher output/higher performance engines, require higher octane fuel as to prevent premature ignition.

Putting high octane fuel in an engine that doesnt require it, does nothing more than burn like low octane fuel in the engine. But putting low octane fuel in a higher compression engine, will as i said above, cause premature ignition.

The ONLY way one can get more power from higher octane fuel, is if this person has wrongly put low octane fuel in the automobile that requires high octane, and suddenly put high octane in, and noticed what the engine can really do. Modern cars have computer controlled engine management, which can sense this premature ignition, and retard ignition timing to compensate for it, but you suffer greatly by a huge performance loss if the computer has to do this...
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Unread 10-09-2006, 03:01 PM   #2
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You do indeed suffer a huge performance loss when you put the wrong fuel in and the computer has to compensate. A friend of mine had a 1995 Acura Integra GSR and in the manual it said the car could run on 85 octane but it would lose over 20 hp. Needless to say he bought premium. So remeber always give it premium if it needs it.

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Unread 10-09-2006, 05:16 PM   #3
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Whoa, 85? I know that "regular" in most places is 87. Premium can be 91 or 93, which I think is overkill for a GSR.
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Unread 10-10-2006, 01:07 AM   #4
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85.5 is regular in Montana. 91 is premium here which is what a GSR needs to run at its best.

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Unread 10-10-2006, 04:15 PM   #5
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Ya i have never seen 85 octane before... 87 is regualr here, 89 mid, and 93 premo.
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Unread 10-10-2006, 07:12 PM   #6
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85.5, 88, and 91 in Montana. I actually didn't know that it was different in other states. I lived in California for a year when I was 12 and the octanes might have been different but I didn't take notice if they were.

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