Abstract: An apparatus for improving fuel economy and abating exhaust gas pollution for four cycle, reciprocating piston, internal combustion engines or rotary engines, including a water reservoir, a heat exchanger for converting water from the water reservoir to steam, a conduit for conveying steam to a water trap in which steam from the heat exchanger is separated from liquids in the steam, a conduit for conveying steam from the water trap to the carburetor, a mixing chamber attached to the carburetor for mixing the steam with fuel, and a heat exchanger for heating fuel prior to the entry of fuel into the mixing chamber.