This may be oversimplified but here goes; amps x volts = watts. 1 hp = 746 wats. electric fan =1.28 hp according to the earlieir test. 65 amps @13.65 volts = 887.25 divided by 746 = 1.189 hp so their tests ar accurate or they couldn't get an accurate test at that low a hp measurement so they just did the math like I did. If another fan takes 20 times the energy to run even at 50% efficincy it still has to be moving ten times the air as an electric fan. Also a good system uses the extra volume of the radiator to maintain a buffer of cooler liquid to allow for periods of more heat/less cooling like long hills and stop lights. If your system isn't keeping your average temp. comfortable then you have no reserve for those hot moments.