you're exactly right. higher octane burns SLOWER, thus preventing hot combustion chamber tempatures from igniting the gasoline BEFORE the sparkplug sparks (this is called detonation). with detonation, you've got rapidly expanding gases in two or more chambers that are on opposite sides of the crank. something has to give, and it's probably going to be a rod or a piston/piston ring. anyone that's run a turbo engine knows this, and that's why most turbos run 93 octane (or higher), because of the higher charge tempatures of the air mixing with the gas. most modern sport bikes have very high compressions which causes the air to become hot (higher pressure = hotter, lower pressure = cooler). so many sport bikes (like mine) suggest 93 octane to prevent problems with detonation.

so if your bike manufacturer recommends a specific octane, NEVER go below it.

and another common misconception, lower octane fuel actually can create more horsepower due to it's quicker combustion. that's why the rider mentioned uses a lower octane on the drag strip. but if you can control the charge tempatures and have things tuned to prevent detonation, it's not a bad idea.

 

93 because I'm not running 87 with 11.6:1 compression regardless of what the owner's manual says Besides the gas mileage is excellent so it's only a few bucks more/month at the most.

 

another turbo owner that knows about compression and charge temp

 

89 because its what it says, i've run 93 and thew bike felt sluggish compared to normal. My rx7 i always ran the cheapest i could find(rotary no detonation problem) And i ran it in the IT series of SCCA.

 

Negative ghost rider, like moldy said it burns slower. The reason some people may feel an increase in pick up and others don't is because some bike probably detected a knock and retarded the ignition enough to get rid of it (making pick up sluggish). Older bikes without all the fancy smhancy stuff may not be able to retard the ignition based on knock. < ?

And the reason you get more hp or whatever you end up with with higher octane is because the motor can advance the timing more.

 

Your engine might.

 

damn, I feel like a cheapass. Wouldnt' the bike run differently?

 

93, because that's what the little sticker on the tank says

 

listen to your bike, it's probably smarter than you

 

I use 93 when I'm running on the street. I use it because I have high compression and I'm mapped for it. I run Sunoco 112 octane on the track with a different map because it gives me a bit more HP, (with high compression), the bike runs cooler, and a little smoother throttle response. (Could be the map though LOL)

Turbo bikes can use low octane fuels because they usually run lower compression then stock so they can pump more boost into the motor.

The lower the octane fuel the hotter it burns and the more HP you get. Higher octane fuel burns cooler and more efficiently, but gives less HP.

On another note: what mostly matters is how your bike is mapped and how it's built as to what fuel gives you the best performance.