Do i really need an engine fan? Not electric ones, but the one that runs off of the engine. I have seen a lot of cars on here without them, does it make the car run hotter? Does it free up any power?

 

you must have either electric or clutch fan because otherwise you'r car will overheat and destroy itself.

 

Does the electric fan really save much horsepower over the clutch fan? Does anyone have any real numbers?

 

I've seen numbers quoted y various "reputable" sources, up to 15 HP. That seems a bit much to me though. I know it's alot; a typical clutch-fan vehicle will gain 2-300 RPM in fast idle at a cold startup, when the clutch decouples.

It would be pretty easy to measure; all you need is back-to-back dyno runs without the fan. Just take off the 4 nuts, remove the clutch & fan, put the nuts back; leave the belt there, the WP & alt working, etc.

 

An electric fan isn't always running. When its not running, its not drawing any power, so its not using up any horsepower thought the alternator. When its running it will draw power through the alternator, which puts a load on the engine, using power.

Basically, an electric fan will only use power when its running. The electric fan should only be running when the engine is getting a little hot, so thats the only time it should suck up any horsepower.

 

Isn't that what the clutch is for as well? How much power is the mech. fan draw when the clutch is slipping? The clutch probably engages at a lower temp then the electric fan.