Abstract: A device for improving combustion efficiency comprises one or more magnets for negatively charging fluid fed through a fluid passageway to a combustion chamber of a combustion apparatus. The device includes a housing containing a permanent magnet assembly having at least one magnet positioned adjacent the fluid passageway. The magnet is arranged with its north pole closer to the fluid passageway than its south pole, and preferably with its north pole between the fluid passageway and the south pole. The device improves fuel efficiency, increases power production, reduces carbon build-up on engine parts and reduces pollutants in exhaust emissions.