This paper demonstrates the methods used to design an automobile engine cooling system. Basic terminology associated with the cooling system is defined. Topics covered include the radiator, fan, and coolant. The radiator is described in detail. The advantages of aluminum over copper/brass radiators are discussed, as well as the numerous tube, fin, and core designs of automobile radiators. Finally, experimental methods used in radiator and cooling fan selection are discussed. The experimental methods include dynamometer testing and the development of radiator/fan pressure drop vs. volumetric flow rate curves. Experimental data for radiator/fan curves of a typical racing car cooling system are presented. In addition, analytical techniques used to determine the maximum cooling capacity of radiators used for the Comell University Formula SAE Racing Car Team 1996 are described.