A fuel injector adapter for providing nitrous oxide to an internal combustion engine is disclosed. The nozzle has a central fuel injector passage that terminates at a first outlet end. Fuel from a fuel injector may be passed through the central fuel injector passage. The nozzle also has an inner annular passage. The inner annular passage terminates at a second outlet end. The nozzle also has an outer annular passage arranged circumferentially around the inner annular passage that terminates at a third outlet end. One or both of the inner and outer annular passages is adapted to pass nitrous oxide through it. The nozzle is adapted to fit between a fuel injector and an engine without substantial modification to the engine.
