electric cooling fan

[Jon581]

i have seen them in rwd cars/trucks
and i am not trying to start an arguement with anyone just curious why some car's come like that and some don't.

 

[OilPatch197]

Mechanical fans, at that exact point where the fan rpm and airflow matches the vehicle speed...yes they're fine. but that depends on engine rpm, gear, speed, etc. the other 95% of the time, they are still dragging. The arguement is the additional inertia to accelerate/decelerate the fan, not the cruising drag. At very high speed and engine rpm, they do still do something.

 

[fastpakr]

Yes, they do exist in those applications occasionally, frequently for fitment issues. Again, nobody is saying that electric fans are bad/don't work/don't exist in rwd applications. They're just unnecessary in most cases and don't provide the significant advantages that some people think they do. There are times to use them, but in most cases the mechanical fan works just as well.

 

[fastpakr]

Mechanical fans, at that exact point where the fan rpm and airflow matches the vehicle speed...yes they're fine. but that depends on engine rpm, gear, speed, etc. the other 95% of the time, they are still dragging. The arguement is the additional inertia to accelerate/decelerate the fan, not the cruising drag. At very high speed and engine rpm, they do still do something while ridding some weight on the water pump bearing, in my experience the water pump's life will about double.

Where is this mythical exact point? You seem to have blinded yourself to the concept that they are thermally clutched. In nearly all cases, they are just as efficient as electric fans because the engine is only powering them when they are needed. At low engine speed they can be fully locked if the water temperature requires it, and at high engine speed they can be unlocked if not required. The 'exact point' doesn't exist. It's in your head. What additional inertia are you referring to? If your point is that they are already spinning, then that argument only comes back in your face because the inertia is working for them. If your point is that they need to be spun up, then your argument that the fan clutch is causing them to be powered by the motor has fallen through. You can't have it both ways. Each type of fan puts drag on the engine. One directly through the belt, the other indirectly through the belt->alternator->electric motor.

Somehow you have forgotten the laws of physics.