So what did U.S. Radiator learn?  First and foremost, they discovered that where the radiator is concerned core design and NOT material had the greatest effect on temperature drop.  While all radiator cores might look the same they perform differently based on tube spacing and fins per inch.  Heat transfer points where temperature is actually allowed to leave the radiator are where the fin is bonded to the tube.  The more transfer points, the greater the temperature drop. A 60’s core for example had a 1/2” tube spacing (ie, 1/2” fin between the tubes) and by going from a two row radiator to a four row core design they were able to double the heat transfer points which resulted in a 15-20% increase in temperature drop without changing the other variables (air flow, coolant flow).  In the 80's the Japanese came out with a core design in response to the need to down size, which has become the standard, and was efficient enough to allow the re-introduction of aluminum (a less efficient heat transfer material) at the O.E. level.  By changing the tube spacing to 3/8", a design referred to as High Efficiency in the industry, more tubes or water passages and fins were allowed across the face of a core with a specific width in inches.  The design was simple enough but proved to be very efficient in that more heat transfer points created greater temperature drop inlet to outlet. At this point the move to aluminum construction was purely financial in that raw materials are purchased “by the pound” and a finished aluminum radiator weighs about 25% of a copper/brass unit (dollars per pound being almost equal at that time) and resulted in huge savings to the O.E.’s .  This is why we’ve seen most copper/brass manufacturers either switch to aluminum or fold up their tents permanently.  It is important to note that this decision was based solely on financial savings and should not be confused with more efficient.

You can get  either aluminum or  copper / brass radiators at