Originally Posted by
HenryJ
While the stock clutch fan may exceed the CFM available from an electric at higher engine speeds, electric fans really shine at lower speeds.
I am unable to get a consistent rating for either the stock or electrics in my case. The stock fan pulls in excess of 4000 cfm. The dual electric fans 3800 cfm. At idles speeds they pull as much as the stock fan does in the higher rpms. It does cool much better than stock. The AC works better, the engine stays cooler.
Anytime you add a load to the electrical system you should also consider the systems affected. My vehicle has a CS130D alternator that is rated at 100 amps. As with the cfm rating for fans, that is maximum, not idle speed where I need that power. At idle speeds it would produce just over 50 amps. The 14 amp load I added is over 20% of that capacity. With all the accessories on it was more than was available and there was a voltage drop. Voltage drop for the fans means lower speeds and less air.
Another problem from over taxing the alternator is the heat that is generated and the associated decrease in lifespan. Neither are desirable.
Airflow is not the only part of the puzzle. In my case the reservoir of coolant and the surface area of the radiator were insufficient for a hotter climate. I increased the radiator size and capacity. Next the stock temperature range was just too close to the edge of hot. I installed a lower temperature theromostat. Now you must match the engagement point for the clutch fan. The stock clutch fan engages way too late in my opinion. There were no lower temperature clutches available, and eliminating it is not a good idea to maintain performance and mileage. Electrics are easily adjustable.
Maintaining fan speed and voltage by adding a bigger alternator was the last piece. It has been working well for me.
Pros, and Cons.
The stock fan is pretty hard to beat. It moves lots of air. It is simple. The clutch is performance friendly and really does a good job. It is simple and virtually break proof. The stock mechanical fan is a very good set-up.
It is not adjustable. It may not pull enough air at low engine speeds. It can be very loud when the clutch is locked.
Electrics are nice. Faster warm ups. In the wintertime they rarely turn on around here. Adjustability. Better airflow for the AC when idling. Manual override. They are not turning all the time requiring engine horsepower. There may be some performance and mileage increases. (the stock clutch fan does a good job, increases may be minimal at best)
Would I do it again? Yes. If a lower temperature clutch had been available would I have done that? Perhaps, but the benefits of the electrics would likely have drawn me that direction eventually.
Each application is different. Install it right and consider all the things it will effect. Do it right using properly sized fan, wire , fuses, relays, thermostatic controls, etc.
The majority of vehicles on the road are using electric fans. They are dependable and durable. They do have a place in an offroad vehicle.
Electric Cooling Fans
Part Number:67017Weight:14.3 lbs.
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