I measured the current draw of the stock fan - the inrush current peaks my 20A linear power supply (peak current duration is pretty short, but the data logger of the power supply picked it up, next I'll put it on the scope).
I don't have all the currents available to share at the moment, but I tested at 9V, 12V, 13.5V, and 14.4V (14V) The original harness limits the voltage at the fan - best option is to wire a relay and a fused feed off the battery. There is a noticeable improvement in fan speed - judging from the change in sound. I didn't measure the RPM, my tachometer can't be found at the moment!! I installed a relay on my car, and the fan has never sounded healthier! (albeit, it is LOUDDDDD!!)
Ideally the voltage at the fan is 14V (ideally the voltage is this high at the fan, unfortunately it's far less with the stock harness - I've measured as low as 10V with the alternator putting out 13.5V at idle) - one fan with application static pressure using a 17 tube 3-core rad measures 15.3A with the power supply set at 14.4V! - It is pulling a LOT of air. My next step is to try and measure air flow in CFM. At 13V, the current dropped to 13.66. Lower voltage, the current draw is less - but so is the amount of air its pulling. Lowering the supply voltage "sounds" very different.
I imagine the stock fan pulls a lot of air and does a good job of keeping the car cool in traffic - but it is annoyingly LOUD! In my opinion, best choice of fans is BLDC (brushless DC) - but they're pricey (Spal offers them) but they'd be the most efficient.
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Stock late model fan is just over 2 kg = 4.409 lbs - earlier units had a plastic shroud/frame.
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