I run a seven blade flex fan 17 in dia with stock shroud on a 26 inch
3 core stock brass type radiator .
with a 160 t-stat the eng would run to cool for school , never even got to 180 unless very warm out side . the eng has aprox 600 hp.
had to switch to 195 t stat to correct some air fuel distributon issiues and car still runs 195 on hyway will creep to 210 if sitting in trafic to long but still ok .
I have a friend with a all alumnum 850hp hemi that runs stock seven blade fan with the viscus thermo clutch and keeps cool and says that he has tried every fan out there and none can beat the factory seven blade pulls about 4000 cfm so he says . try to find electric fans that will fit on a 26 in radiator and pull like that ! very dificult !