How long does it take to burn different grades of gasoline?

How long does it take to burn different grades of gasoline?
That is a very great question and very difficult to answer without further clarification.
The power in gasoline is measured in octane. The higher the octane the higher the explosive power and in most applications, the less needed to get the same desired power.
When one adds Alcohol and other lower octane type additives it reduces the volatility and reduces the mileage per gallon. The new alternate fuels from corn and soybeans is not a friend of gas mileage. It only brings higher revenue to farmers & Oil companies and causes PRETEND change over higher prices to be charged by oil companies. Do you really believe the oil refinery cleans out a tank and starts the new mixture every spring when the Memorial Holiday comes and they can spike the price of gasoline to steal Billions of dollars profit? Do you empty you car gas tank and clean it out for the "Spring gas"? of course not! It is more political to sell corn than really reducing pollution and actually can do more harm to the environment than cleaning it as so advertised. A Chevrolet Suburban which can burn alternative fuel will travel aprox 300 miles on a full tank of Alternative fuel opposed to 500 miles on 87 octane gasoline. You put more hydrocarbons into the air using more fuel to travel less miles paying oil companies more or the same per gallon getting less miles. So, how long does it take to burn it? Wow! How long does it take to drive 300 miles on a tank or 500 miles on a tank? So you see, it's hard to answer in that manner. Hope it helped. Fullait