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What number of octane do you guys run in your racing fourwheelers, and why???
 

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I run 91. That is the highest pump gas available hear. This is written about cars but it is the same concept...

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.
 

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You don't need anything higher than 91/92 unless you have a high compression piston
 

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We have a pump here that has 110 leaded. It's purple. I ran it a (mixed with 91) couple times in my 400ex. It smells great coming out the other end. lol Other than that I just run 91. My 400ex is all stock engine.
 

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I run 104 octane when we go out on all day rides I get better milage and the quad performs so much better. I also run a mix of 93 and 104.
 
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