As part of a continuing program to improve performance of copper and brass radiators and thus obtain improved material utilization, heat transfer performance of a standard cross-flow automobile radiator and stresses existing during operation were measured under normal operating conditions and at various other temperatures and pressures. It is well known that heat transfer performance of a radiator can be improved by raising the operating temperature and, thereby, the saturation temperature. Therefore, if the operating pressure and temperature can be raised while holding stresses within allowable limits by improved design with little or no increase in cost, a smaller, lighter and less expensive radiator should result.The standard radiator performance was evaluated using brittle coat testing, strain gages located at a number of points on the surface, and thermocouples at many points on the radiator surface. Measurements were made under various air flow, air temperature, coolant flow, coolant temperature, and pressure conditions.Knowledge gained from the data obtained in the series of tests was applied to the design and construction of a new radiator intended for use on a prototype automobile. The new radiator has cylindrical tanks and a single deep tube row. Preliminary results show that peak stresses in the new radiator are reduced by a factor of about 6 compared to the standard radiator. Thus, the new radiator can be operated at 22 psig while stresses in the standard radiator exceeded the yield point at this operating pressure. The new design will permit operation at far higher pressure levels with substantially hydrostatic conditions in the radiator.Production processes used on the new radiator can be economically applied to mass production of radiators for automotive application and also permit simple, in-field repair.