The present invention provides methods and apparatus for premixing fuel and oxidant for combustion. The methods and apparatus may include a two stage vortex, each stage accommodating different flow rate ranges. The vortex pulverizes fuel and optimally mixes the fuel with an oxidant prior to introduction into a combustion chamber. The premixing results in more complete combustion and, consequently, fuel efficiency may be increased and pollution may be decreased. The present invention also enables introduction of fuel and oxidant to an engine without creating any shockwaves in engine cylinders, which may otherwise occur with current fuel injection systems.