Direct injection of gasoline in engines with spark ignition is starting to become more widespread as it is generally more efficient especially at low load conditions. DI creates a stratified charge situation depending on the method of DI by injecting the gasoline at a particular spot on the top of the piston which makes the fuel and air swirl just prior to detonation. With DI gasoline can be injected into a cylinder more than once during the stroke again adding power after the detonation has started.
Di (Direct Injection) is complicated and requires a computer to manage correctly taking many inputs such as oxygen content, pressure, temperature, RPM’s and power required, the gas pedal.
Since Gasoline engines generally provide about 25% of the power produced when gasoline is burned that means that 3/4’s of it is wasted in the radiator. DI can improve that to over 30%.
Eventually when we get rid of the valve train with opposed piston designs we will get near 40%. When we learn to make high temperature ceramic parts we will be able to get over 50%. Think of that, if a car today gets 35MPG it would get 70. Talk about being energy independent. . .
Gasoline technology has a long way to go and will be around for a long time.