Fuel Octane Measurement

No easy way. Online octane anaylzers are expensive, complicated, and delicate. too much so for use in a commercial automobile. Of what use would this information be, anyway? The better bit of information, I think, would be "Is the fuel of sufficient octane for the operating conditions". Insufficient octane allows preignition and damage to the engine under various conditions. Modern electronic systems monitor for the occurance of preigniton and attempt to compensate by varying the fuel ratio and / or the ignition timing. These systems are capable of compensating for almost all conditions within their market location of available octane availability and the designed capability of the engine-vehicle combination. If you are operating outside of these paramaters you are either abusing the vehicle or you need to consider where you are buying your fuel.

No, but if you want to be sure use 1cc of fuel grade hydrogen peroxide per gallon of regular gas and you have a "certain" 95+octane.

This isn't exactly on track with this discussion, but seemed as good a place as any to mention it.

My brother used to race dirt bikes, and was also an interprovincial mechanic (Canada) and he told me that they would put a couple of moth balls in the tank (naptha), and fill with regular gasoline, and the moth balls would raise the octane (lower the flame volatility) and make a better racing fuel.

I tried this in my car, but I had the feeling that it clogged my fuel injectors...

Chris

That's very handy information, but where would one go to purchase fuel grade hydrogen peroxide?

Gasoline is a complex fuel.

Just use the knock sensor as a guide line. The better the grade fuel for your combination the less knock will be seen. I have found Shell and Union 76 pump 93 octane to work better than others in my own car. Least amount of knock and ignition retard under light and heavy throttle.

Yup, moth balls really DO work - but they also eat valves!

Yep mothballs work, and eat valves, thats why you use castor oil as a top lubricant. The smell is distinctive and will likely earn you a fuel check in competition, but it is an old, old, dirt track racing trick.