A number of things contribute to cooling efficiency, e.g.; fluid capacity, fin design, material, etc. Zionsville Autosport's Alloy Radiator has a core thickness of 43 mm. The surface area of ZA's E31 850csi Alloy Raditaor is 376 square inches - the same as a stock radiator. Additionally, we use a high efficiency core similar to a stock radiator. High efficiency cores have more fins per inch, more tubes per core and more cooling capacity. Each row has a single, large tube. The flat side of the tube is in direct contact with the fins which transfers heat from the tube walls to the fins. Since the rounded ends of the tube are not in direct contact with the fin, this portion of the tube does not aid in secondary cooling. The more tubes per row, the more rounded ends, and the less direct contact there is between the tubes and the fins. ZA uses a single tube for better heat dissipation. Cooling improvement also comes from larger radiant surfaces on the tanks. The alloy tanks themselves have a high level of thermal conductivity which helps to dissipate heat into air instead of back into the engine. In addition, the tanks on ZA's Alloy Radiator are larger than the tanks on a stock radiator. This results in a 65% increase in coolant capacity.