This paper assesses the effect of material thermal properties on the performance and manufacture of brazed radiators made of aluminum and of copper/brass. Analysis is presented to show that copper/brass cores can be closely weight competitive with brazed aluminum. This is because the higher thermal conductivity of copper allows use of thinner fins. The thinner fins result in approximately 38% lower air pressure drop for the same frontal area and performance. If the cu/br design is designed for the same air pressure drop as the aluminum core, one may obtain frontal area reductions as large as 16%. Analysis of the effect of the different core materials and material thickness on the core heating time is presented. It is concluded that the thick header controls the core pre-heat time. Further, it is estimated that the required pre-heat time for cu/br and aluminum cores would be approximately equal. Because the specific heat of copper (or brass) is 42% that of aluminum, the preheat thermal energy for a cu/br core having the same weight as an aluminum core would be 42%.