90% BOIL POINT

It is important for racers to look at the 90 percent boil point. The higher the 90 percent temperature, the more difficult is to vaporize and combust the gasoline. When it is more difficult to vaporize and combust the gasoline, unburned gasoline passes the exhaust pipe and results in a loss of horsepower.

When gasoline burns out the exhaust pipe, the jetting is drastically wrong or end boiling points are too high. It also interferes with the proper exhausting out the combustion chamber by introducing reverse shock waves.

With regards to the top-end distillation point you need to be careful on higher end of the distillation characteristics, more so than the lower end. When the 90 percent is in the 260-275 degree range, which is about as high as you want to go. Above that, the gas can’t vapor quickly enough to burn and produce more power.

Racing gas can also have a tail on it. That means the final boiling point is too high. The last 10 percent of fuel is getting harder to vaporize.