A method of operating an internal combustion engine comprises the steps of (a) pressurizing a liquid fuel to a pressure above 150 psig; (b) heating the liquid fuel to a temperature above 500° F. to produce a heated liquid fuel; (c) suddenly reducing the pressure of the heated liquid fuel sufficiently to vaporize the heated liquid fuel to form a vaporized hot fuel; (d) combining the vaporized hot fuel with oxygen to form a vaporized hot fuel/oxygen mixture; (e) introducing the vaporized hot fuel/oxygen mixture into the internal combustion engine; and (f) combusting the vaporized hot fuel/oxygen mixture within the internal combustion engine.