Experiments were performed with a 5:1 scale model of a portion of a typical louvered-fin heat-exchanger core in a controlled turbulence wind tunnel to determine whether full-scale heat-exchanger characteristics could be obtained from large-scale data. The air-pressure drop and heat-transfer rate of the model core were measured and compared with the full-scale data in terms of drag coefficient and Nusselt number as a function of Reynolds number based on the face velocity. These data showed a close correlation between the model and full-scale cores. It is concluded that the airflow phenomena are similar for the full-scale and model cores.In addition to the pressure drop and heat-transfer measurements, distributions of airspeed and air temperature at selected locations in the wake were taken with hot wire and thermocouple probes. These distributions provided a detailed description of local airflow phenomena in the core.