The Truth About Electric Fans

[Cadillacmak]

I keep seeing posts on electric fans and there appears to be a lot of mystery behind them. So here are the facts and some comments to help you decide if you really want them or not.
Watch this -

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30hp to drive a fan isn't 30hp gone, they used 30hp to move air. That is the way fans work, if a fan is designed to be 30hp, that is a rating at a certain RPM, at a certain temp, with a certain humidity. And it will move 30hp of air. But... your truck driving down the road will not use 30hp to move that air unless you blank off the grill. The air is already moving across the fan forced in from the grill via the horse power it takes to move your vehicle through the air. So if you have 25hp of air coming through your grill and you have a 30hp fan, your engine will use 5hp from the front of the motor to power the cooling. But you are still using 30hp because 25hp is deliver to your back tires to smash that air through your grill. No matter what, it takes energy to move everything, including air, and we are moving it with HP.
Moving on to electric fans. If the 30hp fan in the video is to be replaced with an electric fan, this is the wattage we need to get the same fan. 22,380watt fan, thats right! hp x 746 / volt x %efficiency.
So now it depends on when you need that cooling and where the fan is getting its air. If your over heating at idle in your big block 70's Vette, the electric fan will make your life better. If you have a very aerodynamic front end (to save HP) an electric pusher fan might help disturb the air that is trying to go around your vehicle because its closer. But if you are overheating pulling your trailer down the highway at 80mph, well I found you a fan https://www.indiamart.com/proddetail/30hp-industrial-axial-fan-2850043568655.html

I am not against electric fans, I have them I my 75 F250 for crawling uphill in 4low.

 

[TonyM]

Love me some e-fans.

 

[Cadillacmak]

My 75 F250 will overheat on the highway on a hot day if I try to drive over 65mph because I have 4.10 gears and no overdrive. This is not a problem because I do 60 (Alaska roads are terrible) and we have very few hot days. Half of the year we are trying to prevent cooling by covering our grill or putting cardboard if front of the radiator. So electric fans are ideal for this truck.

 

[99xcss4]

imho booth mechanical and e fans have their own place some e fans are better then other e fans some times you need to leave well enough alone just do the most fan blades and most hd clutch you can get what I will say about e fans though is you a good electrical system for them high output alternator big 3 and good battery or batteries and here is the thing are you really gaining or saving power and torque you are not spinning a fan and clutch any more but you are still spinning a water pump the energy not being used by the fan and clutch is now being used by the alternator you could swap to a electric water pump so you would then only have to turn your alternator and power steering pump and you may save some energy but again are you really saving any thing because your alternator will be doing even more work to keep up with the electric water pump to me it seems like a wash they both have a place and it comes down to what you are trying to do and the will pick what one you go with it is a great video though

 

[L31MaxExpress]

I will keep my clutch fan. I had already been climbing a grade for a couple of miles at that point. I had an ~8,000 lbs tandem axle enclosed trailer behind me.

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[L31MaxExpress]

When I was in Colorado, climbing mountain passes in my Pathfinder with snow on the ground, the fan clutch was engaging at 60+ MPH on many of the climbs. Forward motion of the vehicle alone is often not enough to keep it cool.

 

[Cadillacmak]

I will keep my clutch fan. I had already been climbing a grade for a couple of miles at that point. I had an ~8,000 lbs tandem axle enclosed trailer behind me.

And the reason you want to keep your clutch fan, is that you need to move lots of air. And that takes lots of HP.

 

[L31MaxExpress]

And the reason you want to keep your clutch fan, is that you need to move lots of air. And that takes lots of HP.

Exactly and by controlling when the fan runs it helps minimize that power loss. At WOT the PCM controlled fan clutch is mostly disabled until 210F. I have the fan setup to mostly freewheel until the engine hits 210F or additional cooling is needed across the condenser or transmission cooler.

 

[Cadillacmak]

When I was in Colorado, climbing mountain passes in my Pathfinder with snow on the ground, the fan clutch was engaging at 60+ MPH on many of the climbs. Forward motion of the vehicle alone is often not enough to keep it cool.

We have some steep grades here and when pulling a camper out to go fishing in the 97 Suburban, I would only want the mechanical fan.

 

[AuroraGirl]

Exactly and by controlling when the fan runs it helps minimize that power loss. At WOT the PCM controlled fan clutch is mostly disabled until 210F. I have the fan setup to mostly freewheel until the engine hits 210F or additional cooling is needed across the condenser or transmission cooler.

your fan clutch is pwm? or is it just a fan clutch which is otherwise mechanical that the PCM can choose to disengage?