Abstract: A multi-fuel gasifier system for internal combustion engines comprising a hollow casing having heat conducting plates therein in thermal contact with a heat exchange duct passing through the casing through which hot exhaust gas passes from the exhaust manifold to the exhaust pipe, a gasifying chamber substantially centrally located within the casing and surrounded by the heat conducting plates and defined by inner wall portions of the plates. An inlet in the casing wall communicates with one end of the chamber and the outlet of the carburetor. An outlet through the casing wall communicates with the other end of the chamber and the intake manifold of the engine. Adjacent the inlet end of the chamber is a first perforated vaporization cap through which fuel-air mixture from the carburetor passes and thereafter contacts a second conically shaped vaporization cap which deflects and sprays the fuel mixture into the vaporization chamber.