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jonnythan wrote: First: I don't think there's an easy way to answer that question, as it depends highly on the engine, intercooling performance, etc.

Second.. what an odd way of going about it. It sounds to me like you want to use high-octane fuel in your bike, and you're curious about how the engine needs to be tuned in order to use high-octane fuel. What seems more logical to me would be to ask how to get a certain level of performance increase out of your engine, and, if that involves increasing engine compression ratios for more HP, what octane rating must be used to achieve the desired performance. The way you're going about this makes it sound like you care way more about having the "110 octane" to throw around than actual performance.

well i am curious about how much difference it makes.

but like i said... i can't afford it. and it is a waste, unless you are racing.

if it will work on my bike, i'll try it once just to see how it is... but it's not something i'll use regularly unless i become a club racer.

VermilionX wrote:if it will work on my bike, i'll try it once just to see how it is...

Your engine will run with it in. I hear it will smell different

If your bike isn't pinging on the fuel you're currently using, then filling up with 110 will actually do your engine harm and cause a loss of power. Your bike lacks the necessary sensors (O2 sensor, knock sensor, etc.) to "know" when a high octane fuel is being used so it can advance the timing to take advantage of it. By running 110 with your bike as-is, you will end up fouling the plugs and covering the inside of your cylinders with carbon build-up. Compression ratio is but one of many factors that determine which octane rating to use. Higher octane fuel does not contain more potential energy (not significantly more, anyway), it simply resists pre-detonation in an engine that was built to produce more power.

ZooTech wrote:If your bike isn't pinging on the fuel you're currently using, then filling up with 110 will actually do your engine harm and cause a loss of power. Your bike lacks the necessary sensors (O2 sensor, knock sensor, etc.) to "know" when a high octane fuel is being used so it can advance the timing to take advantage of it. By running 110 with your bike as-is, you will end up fouling the plugs and covering the inside of your cylinders with carbon build-up. Compression ratio is but one of many factors that determine which octane rating to use. Higher octane fuel does not contain more potential energy (not significantly more, anyway), it simply resists pre-detonation in an engine that was built to produce more power.

thanks zoo.

ZooTech wrote:Higher octane fuel does not contain more potential energy (not significantly more, anyway), it simply resists pre-detonation in an engine that was built to produce more power.

Higher octane gas actually has less energy per molecule than lower octane gas.

I've seen HP ganes on 600cc bikes with minor mods and tuned for regular gas. the only way to tell if it's really better is to put it on the dyno with the race gas. Then again you also get bikes that give more HP on low octane. You can have 2 of the same bikes side by side and they can both run higher HP on different octane gas. The smell is definately great! If you want to look at some good race gas try MR9, I'm pretty sure it's 110 octane.

Skier wrote:

ZooTech wrote:Higher octane fuel does not contain more potential energy (not significantly more, anyway), it simply resists pre-detonation in an engine that was built to produce more power.

Higher octane gas actually has less energy per molecule than lower octane gas.

I honestly don't know either way, but I assumed since there are more octane chains (eight carbon atoms in a chain) in premium that it would have more potential energy.

ZooTech wrote:

Skier wrote:

ZooTech wrote:Higher octane fuel does not contain more potential energy (not significantly more, anyway), it simply resists pre-detonation in an engine that was built to produce more power.

Higher octane gas actually has less energy per molecule than lower octane gas.

I honestly don't know either way, but I assumed since there are more octane chains (eight carbon atoms in a chain) in premium that it would have more potential energy.

I was informed due to how the molecule is arranged you can't get as much energy out of it as a differently arranged molecule. However you can fix that by stuffing in more of the "less-powerful" molecules in there through forced induction since they are resistant to predetonation.

Less energy per unit but you can cram in more units safely so you come out ahead in the power game (but not in efficiency!).

To wander off the beaten path of this thread a little...if you are looking for a little more oomph out of your fuel:

You can buy a gallon of nitromethane (about $25 where racing fuel is sold) and add 2.5 to 3 ounces per gallon of gas in your tank. This will give you slightly more kick than when running pump gas without going through a lot of tuning hassles. It does this because of the extra oxygen molecules in the formulation. Make sure you mix it well and use it soon after you put it in your tank as it will settle out after about a week and make for a little erratic running for a short while.

A friend I ride with does this in his V-Max all the time. Why he does this is beyond me as neither of us rides hard enough to need it. He just swears that is what he wants to do (in a curmudgeonly manner of speaking) so I tell him to spend his money and have his fun. I have ridden his bike with and without the mixture and you can tell a difference by "the seat of the pants" method, but it takes a little bit of enthusiastic riding to come to this conclusion.

As far as it goes with my bikes...I run the grade recommended by the maker. Gas is expensive enough as it is without buying a more expensive grade that you don't need.

Nitromethane is a reasonable additive for running a carbed engine at higher than jetted altitudes because it provides more complete combustion when running rich mixtures. Not worth the $$$ though.