There are certain people who believe that you MUST vaporize the fuel because of what someone wrote, and thinks it is THE factor in distribution (its not) and that you can never get the fuel too finely atomized and then vaporized too soon.
"Unfortunately proper vaporization doesn't occur in most engines. The issue of vaporization is not fixable by any other means other than managing the energy input to the fuel prior to ignition. Firstly lets distinguish vaporization and atomization. Vaporization is liquid turning into gas, atomization is essential to achieve that in a short time period. I mentioned managing the energy input, the atomization achieved is essential to maximizing the energy input during the intake system and the energy exchange within the cylinder on intake and compression. The whole process of combustion relies upon vaporization.
Petrol or gasoline is a complex mixture of hundreds of different types of Hydrocarbons and some other chemicals in minor concentrations. The Hydrocarbons are the ones of interest. With pump grade sold for the street use unleaded fuels the boiling point of these Hydrocarbons varies from approx 110F to 430F depending on brands etc. Racing fuels boil from 120’s F to 220-260’s F as a general average across brands. Some brands are way different to this but most are similar. By observing some of the difference between street fuels and race fuels you can see that the race fuels are easier to vaporize, they boil completely away into gas at lower temperatures than street fuels. This is a desirable feature for maximum combustion efficiency. You can obtain the various distillation fractions for racing fuels from the manufacture’s websites. A distillation fraction of 10% at say 120F means that 10% of the mass of the fuel will be converted into a gas at the temperature of 120 degrees F. If the temperature to achieve 10% is higher, then that means that the particular fuel requires more energy to gas up the lightest HC’s of its makeup. The other side to this is considering a fuel that has a 90% distillation temperature of 350F and a second fuel with a 90% distillation temp of 230F. The first fuel is not going to be easy to convert the heavy HC’s into a gas for burning whereas the second fuel will be. The first thing to realize from all this is that different fuels achieve different vaporization % at the end of the process.
Unleaded street fuels are very hard to gas completely so why do people expect their hotrod engine with a short compression stroke because of the valve timing to have enough compression energy etc to vaporize unleadedstreet fuel?
