Abstract: The apparatus includes tubular heating elements positioned in carburetor air-fuel paths. Each element has a flow passage therethrough connected to input and exhaust conduits which together define a path for flow of exhaust gases from the engine exhaust manifold to the atmosphere. The inlet flow path and the outlet flow path have flow constricting zones having predetermined areas. These flow constricting zones, as well as the size and configuration of the elements making up the flow path are so proportioned to the size of the engine as to obtain optimum performance with respect to economy and torque or horsepower output. The tubular elements are supported in a plate between the carburetor and the intake manifold in a manner such as to heat the fuel to an optimum extent while minimizing heating of the air of the air-fuel mixture.

Abstract: Methods and apparatus for improving fuel vaporization in internal combustion engines in which a high temperature fluid, preferably the engine exhaust gas, is supplied to flow through an internal passage of heater means disposed in the air-fuel flow path of the engine to heat an external surface of the heater means and to radiate an optimum amount of heat into the fuel for vaporization of the fuel. The flow of the high temperature fluid is controlled to maintain the heat radiating surface of the heater means at a certain temperature which is preferably decreased as ambient temperature is increased.

Abstract: Electric heating means for fuel vaporization in internal combustion engines to improve the efficiency, performance and starting thereof, an optimum amount of electrical power being supplied to the heating means during operation of the engine. An important feature relates to the use of heating units mounted in an intake manifold preferably with there being one heating unit for each engine cylinder, mounted adjacent the intake valve. In an engine having fuel injection, a heating unit is mounted on the downstream side of each fuel injector. Another important feature relates to the provision of means controlled by ambient temperature sensing means for automatically adjusting the optimum amount of electrical power supplied to electric heating and vaporizing means.