ELectric Fans on a Cummins ?

Well you answered your own question. If you drive mostly empty, your fan should never really engage except really hot weather maybe. I can count on my hands how any times the fan has kicked on in my 07 unless I was towing or hauling something substantial. And my radiator fins are all smashed in thanks to my kids a few years ago!
Installing electric fans seems like a waste of time and $ for very little to no gain in a normal daily driver vehicle.

Not a contradiction, not sure I have all the facts correct- if the OEM fan uses 25 hP to move 10,000 CFM and the Flexatlite can move that on 1 hp then it would seem a worthwhile effort.

THat may only be theoretical because there are problems fitting enough fans in the space available to get that volume.

But the performance guys love elctric fans and on the cummins forum many claim to move pretty big loads. But everyone agrees that to get the max out of the truck (13,800 in my case) the OEM clutch fan is still the winner.

I'm not setting out across the rockies with htis rig and I'm not planning to spend $600

The offroad guys, who LOVE elctric fans have evolved some great stuff with fans from certain year Taurus's. Ford put massive fans in those cars so they could put the engine really close to the radiator for more interior space.

So i may build this for less than $100 and monitor my temps with a digital OBD reader.

So if all those numbers (your and mine) are correct then it would certainly benefit to convert to electric fans.

Not really. Read Scotts post above mine and you will see why.

Just for more clarification. A modern mechanical fan is an on demand system. Need little cooling? It uses very, very little power. Need a lot of cooling? It will eat a lot of power and do it's job where an electrical fan can't even come close to doing the job the mechanical fan can.

Will an electrical fan work for you? I can't answer that and neither can you. Sometimes it will work, and sometimes it won't. It will all come down to conditions.

hertfordnc wrote:

Turtle n Peeps wrote:
A mechanical fan will draw about 25 to 30 HP in full lock up mode. Ever see the size of a 25 to 30 HP 100% duty cycle electric motor?

It was not my intent to debate the merits of the electric cooling fan but.....

It does not matter how much the OEM fan draws, the question is how much air does it move and how close can the amount of movement can you get with an electric fan.

I understand the clutch fan moves 10,000 CFM

According to Flexalite their fans move 5000 CFM with 30 amps -

30 amps only equals .5 HP

So if all those numbers (your and mine) are correct then it would certainly benefit to convert to electric fans.

But my interest and my personal situation is different from a lot of people. I only plan to tow about half what the truck is capable of and only a a few times a year. I want to try for the best MPG when running empty because this is my ddaily driver

No offense intended but you're contradicting yourself as the amount of air flow from the compared fans is ALL that matters. If you cant get the necessary CFM out of the electric fans then who cares how much HP your saving because you'll be overheating in summer heat and towing. But if you only plan on towing half the CGVWR then you may be just fine.

Yeah it is definitly not a simple add-on. Takes a thorough understanding of all the factors. Most people buy this much truck to tow a 15,000 lb fiver. My previous TV was a an Expedition and it was adequate. So i'm researching how to make this truck best meet my needs. Empty MPG is one factor as I plan to drive it all the time.

Where i live is relatively flat.

I like the idea that hte AC will be cooler when I'm parked with electric fans (if i don't screw up the wiring)

If you search on the diesel forums you'll find opinions all over the place but always resulting in a cant be done if you plan on towing. There was one person I remember saying that he tried an electric fan on his Dodge Cummins and found he couldnt even drive on the freeway in Arizona heat without overheating.

Also, something to remember is that if the electric fan system isnt properly installed then the A/C compressor will be harmed when the A/C or defrost is on.

Turtle n Peeps wrote:
A mechanical fan will draw about 25 to 30 HP in full lock up mode. Ever see the size of a 25 to 30 HP 100% duty cycle electric motor?

It was not my intent to debate the merits of the electric cooling fan but.....

It does not matter how much the OEM fan draws, the question is how much air does it move and how close can the amount of movement can you get with an electric fan.

I understand the clutch fan moves 10,000 CFM

According to Flexalite their fans move 5000 CFM with 30 amps -

30 amps only equals .5 HP

So if all those numbers (your and mine) are correct then it would certainly benefit to convert to electric fans.

But my interest and my personal situation is different from a lot of people. I only plan to tow about half what the truck is capable of and only a a few times a year. I want to try for the best MPG when running empty because this is my ddaily driver

hertfordnc wrote:
For $600 or so FLex a lite makes a fan kit for the CUmmins 5.9

Anybody using it?
I'm not.


is there a noticable MPG gain running empty?
There has been reports of people that use them pick up a slight amount of mileage (and I do mean "slight".)

Does it work well enough to cool the truck when loaded?

In what conditions? In 32 degree weather? Sure, it will work great. In 90 degree weather with a big load on it? No way.


Bottom line. A mechanical fan will draw about 25 to 30 HP in full lock up mode. Ever see the size of a 25 to 30 HP 100% duty cycle electric motor?

If you have a race truck; it will work. If you haul groceries around; it will work (maybe). If you tow in the US in the summer months; nope, not going to work very good most of the time and sometimes it won't work at all.

Maybe a simple exercise in engineering might help understand the issues...

12volts x 28amps = 336 watts...that is what the OP referenced as the 28 amp electric fan and guessing what he is looking at

I HP = 746 watts

My 7.4L big block needs +15 HP FOR THE UPGRADED severe duty fan clutch

15 x 746 = 11,340 watts / 12 volts = 945 amps to do the same work and that is just for the electric fan motor. How about the AC, wipers, windows, headlamps (100 watt each), AC/heater fan (dash & rear), rear window heater, stereo, ETC...ETC...how big does my alternator need to be?

Now must say the severe duty fan clutch is nothing like the standard clutch...it ROARS and see stuff off on both sides being blown when sitting still

Simple math and plug in whatever HP you wish your fan clutch to need...

There are other attributes...

Like blade efficiency....air foil, dia, RPM, even ducting

Of course losses....like the losses in converting serpentine (RPM) to electrical (12VDC), then losses in converting back to RPMs

Not to say won't work...OEMs are going more and more to electric fans....but....not for large ICEs towing HEAVY with several tons hooked up to their tail...going up an incline for how long !?!?

I've seen the Dodge unit on the bench. It's nice to look at. The Flexilite people were great to talk with. I'm not that happy with the factory 06'+ Dodge electronic fan clutch system. The older non computer controlled factory system was better IMO.