The guy that says a fan on a power stroke is pulling 25HP is either not a cooling fan engineer or forgot to move a decimal place. If he is including the water pump the number is probably still not correct but closer.
I am not a cooling system engineer, but am a Professional Mechanical Engineer and understand thermodynamics as well as pump and fan systems. I was reporting what I read from a person who worked in the automotive industry as a cooling system engineer. The PowerStroke fan is a multi-blade affair about 18 inches in diameter and I have no doubt that it would draw 25 HP (note there's no decimal point there purposely) at highway speeds with the fan clutch engaged. The water pump load is minuscule in comparison. The fan would be running in excess of 2000 RPM. I have specified electric fans running at 1800 RPM with 25 HP electric motors and they're pretty big, and definitely wouldn't fit between the radiator and engine on a SuperDuty truck or any other similar or smaller vehicle.
If that big diesel fan costs 25 hp to drive it, it will cost 25 horsepower to drive the alternator powering and equal electric fan as well, nothing is free in physics.
Very true. There's no such thing as a free lunch.
That's not to say that an electric fan wouldn't work, but it depends on your application. Many modern cars have electric fans (with shroud) A 3.8L Buick I had used an electric fan (it had two fans, IIRC). I also know a guy who ran an electric fan on his PowerStroke that was highly modified (He ran 15's in the 1/4 mile) and was his daily driver. Of course, up here we rarely see 75 F, so he didn't have any cooling issues. If he did that in Barstow, CA it might be a different story.
