An apparatus and method for increasing the ratio of air to fuel of engine is disclosed. The method comprises the steps of providing air to fuel injection mechanism by fan; adjusting the speed of fan by the voltage generated by the generator a car so that the corresponding air from the fan is based on the depression of the accelerator of the car; thereby the air to fuel ratio of engine is increased and the engine provides the best efficiency. The device is characterized in that the front side of the housing is a hollow storage cylinder and a passage is provided to the housing, and a fan is mounted at the passage, and the fan is controlled by a controller based on the speed of rotation of the engine and the storage cylinder is mounted with a filter.