With a B18C1 running through a '92 CX 150k mile single core radiator, I could overheat it doing a lot of high speed (85-90) continuous driving on a 90-100 degree days. I also removed the plastic cover from the A/C side so thinking back, 90% of the air probably just went right past the radiator. I upgraded to a fluidyne radiator and never worried about it again.