View Single Post
Old 06-01-2009, 11:25 PM
GeneFiorot GeneFiorot is offline
Join Date: Feb 2009
Location: Punta Gorda Florida
Posts: 170
Default Re: Bad Occ Chopper Made

Matt167 you are exactly correct! Low Octane gas will ignite sooner with less control causing pinging and pre ignition and detonation. Now high octane gas is needed to prevent those conditions in High compression engines especially with high advance curves. In order to avoid those conditions it stands to reason that High Octane gas has to be actually less explosive all things being equal in fact actually more controlled. The analogy to 80% and 90% alcohol has nothing to do with octane and proves nothing. As far as oxygen in the gas I assume that means the mixture created by the carb or the injector. It is the maximum amount of mixture allowed to enter the cylinder by the intake system and allowable compression ratio without pre ignition, or detonation that results in the power produced. Higher Octane allows for that higher parameter.
You might want to read this before you accuse anyone of talking ****

In most of the U.S., regular gas has an octane rating of 87, midgrade gas is 89, and premium is 91 or 92. (Octane ratings are lower in the mountain west due to the effects of thin air on internal combustion.) Contrary to widespread belief, the octane rating doesn't indicate how much power the fuel delivers; all grades of gasoline contain roughly the same amount of heat energy. Rather, a higher octane rating means the fuel is less likely to cause your engine to knock or ping. Knock, also known as detonation, occurs when part of the fuel-air mixture in one or more of your car's cylinders ignites spontaneously due to compression, independent of the combustion initiated by the spark plug. (The ideal gas law tells us that a gas heats up when compressed.) Instead of a controlled burn, you get what amounts to an explosion--not a good thing for your engine. To avoid this, high-octane gas is formulated to burn slower than regular, making it less likely to ignite without benefit of spark.