Variable fuel delivery system and method

The present invention generally relates to, for example, fuel delivery in internal combustion engines. An improved fuel injector is disclosed. In one embodiment of the invention, the fuel injector includes a first fluid input for receiving a first fluid; a second fluid input for receiving a second fluid; and a drop ejector configured to discretely eject fluid in a digital manner, wherein the drop ejector is further configured to receive the first and second fluids and to eject discrete droplets of the first fluid and discrete droplets of the second fluid. In another embodiment of the invention, the fuel injector includes a drop ejector configured to discretely eject fluid in a digital manner, wherein the drop ejector includes a first set of firing chambers and a second set of firing chambers, wherein each firing chamber of the first set has a first volume, and wherein each firing chamber of the second set has a second volume.