Gasoline engine (Gasoline Engine) is an engine that uses gasoline as fuel to convert internal energy into kinetic energy. Since gas viscosity is small, fast evaporation, can use gasoline injection system of gasoline will be injected into the cylinder, compressed to a certain temperature and pressure, ignited by the spark plug, the gas expansion. Gasoline engine is characterized by high speed, simple structure, light weight, low cost, stable operation, easy maintenance. Gasoline engines are widely used in cars, especially on small cars.