A rather narrow range of exhaust composition must be maintained if a flame-type afterburner is to be used. Assuming such a range of composition, flame-type afterburners are possible. Combustion can be self-sustaining and continuous only with the addition of supplementary fuel or sensible heat. Minimum use of supplementary fuel can be achieved through the use of a heat exchanger which takes advantage of the temperature of combustion to preheat the gas entering the reaction. Both recuperative and regenerative heat exchangers in several different forms were used. The configuration of the afterburner varied according to the type of heat exchanger used and the location of the afterburner with respect to the engine. The location of the afterburner was a prime consideration because of the effect of location on gas temperature entering the unit and the importance of temperature on the reaction. The regenerative type afterburner lowered emissions to values well below those specified in the California Standard. The penalties in performance and economy, while noticeable, were not unreasonable. Very substantial additional development work must be done on materials and mechanical design before these units can be considered commercial.The theoretical considerations and relationships for a high temperature flame reaction and the results of research performed by Thompson Ramo Wooldridge Inc. and Chrysler Corporation on flame-type afterburners are discussed. Data are presented showing the relationships between the various parameters affecting the reaction and the effect of these relationships on heat exchanger design. The various phases of the work and the several afterburner designs are described. Data on the performance evaluation of regenerative afterburners located near the engine and in the muffler position are presented. The data cover the effectiveness of the afterburners and the effects on vehicle performance.