Here's a stupid gee whiz question I was just wondering if anyone knew the answer to for no particular reason...

We always compare cooling capacity of electric fans in terms of CFMs, and I understand that. So does anyone know what a stock, mechanical, clutch fan is rated at around idle??

I guess what got me thinking about this was you always see electric fans not recommended for trucks over a certain gross weight or severe towing capacities and I've often wondered why??

 

I dont think i have ever seen documented CFM ratings on the stock fan setup.

I personally know a single 3000cfm fan is more then enough to stay cool at idle without AC on a single row radiator.

 

its around 4000cfm

 

At around idle?

 

Galaxy,

I'm not sure what the CFM of a clutch fan is, but I can assure you my elec. fans pull more than enough. By the way, take a look under the hood of full size GM trucks and you might be surprised at what's hanging on their radiators.

 

You can't rate a belt driven fan unless the speed of opertion is specified.
An electric fan is usually a single speed, dual or variable so you can't do any compare to a belt driven for absolute airflow unless some measuring standard is used.
Some of the parameters used to arrive at CFM ratings for any given application is based on how large the motor is in terms of BTU heat generation, what size radiator must be used to lose that heat, how much airflow at a stand still will be needed to make heat loss exceed the engine heat production to prevent overheating with A/C etc. So it's not a task you can do without equipment and knowledge.
Best that can be done is trust the mfger has done the testing and rates the fan according to HP , engine size etc then you still don't really know where you are except for trial and error for the application's worst set of conditions of use.