A copper radiator core can be made more efficient by changing the tube spacing and fin count. As I stated earlier the radiators that were made from the 1950�s to the 1970�s generally used �� wide tubes placed on 9/16� centers from each other. If you counted the fins you might get as few as 6 or 8 fins per inch (FPI). If the tubes are placed closer together and the fins are packed in tighter a denser core is created that throws off much more heat. A high efficiency core can have tubes on 7/16�, 3/8� or even 5/16� centers and fin counts increased to 12 to 14 FPI. That may not seem like a big deal but the surface area is greatly increased. As an example; a 26� wide radiator core with tubes on 9/16� centers has about 45 tubes from side to side. A high efficiency core of the same width has 57 tubes from side to side. Combined with all the additional fins between the tubes this provides approximately 25% to 30% better cooling than the OEM radiator had. A three row high efficiency core will cool about the same as a regular four row without taking away another 5/8� of fan clearance.