Mechanical fan vs. electric conversion....real numbers to compare

[snicklas]

I think that may work.

There are some vehicles out there that have a setup from the factory that way.

I had a 2000 Dodge Durango with the 360 V-8 and rear air. It had the normal mechanical fan mounted to the waterpump, and down in front on the very bottom of the radiator/condenser was a small electric pusher that was wired in with the A/C. When the A/C was on, the electric would run. If you were working it hard, the mechanical would kick in. That truck would freeze you no matter the temp or speed. The only coolers that fan blew through were the condenser and the radiator. The transmission cooler was mounted above the level of that fan..........

I would say try and keep it out of the way of the big fan, and you should be ok.......

 

[jaluhn83]

I have an aux electric fan on mine mainly because it came with the intercooler kit. Seems like it should work decently at least to help with AC. Doubt it will have much effect on the main fan, but more air is always nice.

Just remember that a large portion of your cooling comes from air flow simply from the airflow from driving, so anything that blocks that significantly is bad. Plain fan shouldn't cause much, but one with a large shroud would be unadvised.

 

[Greg5OH]

yup my lexus ls400 has a pusher fan to help keep the AC cold. Also has a large mechanical fan. I have only once heard hte electric fan stay on for a brief period. Then again, the cooling system is designed around the fact the pusher fan poses a small restriction in the airflow.
Having said that, Im sure it wont be an issue having a pusher fan.
Right now I have the massive 6.0 intercooler covering my fad, I was grossing 10k today doing 75 mph temp only touched 200 once. EGT was 850. Dont think my mechanical fan even started to lock up yet.
I will be adding the AC condenser though. Truck stays cool...but im not!

 

[cpdenton]

I thought about wiring in a pusher sinc I have this nic controller for fans. I just don't know where I would put it. The intercooler takes up a lot of real estate up there.

I will say that me air conditioner blows much colder at idle now....the dccontrols controller has a provision for the fan to kick on at 50 percent power when the compressor is kicked in. It worked, but not really efficient I guess. Mechanical fan seems to make it blow about 5 degrees cooler.

 

[franklin2]

Just remember that a large portion of your cooling comes from air flow simply from the airflow from driving, so anything that blocks that significantly is bad. Plain fan shouldn't cause much, but one with a large shroud would be unadvised.

This is what I want to comment on, and what seems to be brought out by the numbers in the first post; With all that frontal area we have, and he is doing 70mph, theoretically you would not need a fan. But it's obvious from his numbers at 70. and my experience also, that you do need the fan, even at 70 mph. I can't figure it out, it's not like we have small grilles that won't let the air in.

And you also have to be careful, it's a well known fact that lots of junk in the airflow path like aux fans will tend to block the airflow some, so think about it before you add some. With a mechanical fan that pulls so much air, and a little dinky fan that in comparison pulls very little air, it may be going backwards if the little fan blocks some of the air going through.

 

[cpdenton]

It was interesting to me how much cooler it ran at 70 mph. The front of my truck is pretty wide open. I have the power stroke style bumper cutouts for more airflow too. I have an intercooler, followed by the ac condenser, then the radiator.

I would have thought the effect from any fan would have been minimal at interstate speeds. Perhaps the shroud from the electric fans was blocking some of it?

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[jaluhn83]

I've noticed a difference between a functioning fan clutch and shot at speed as well, but not too much - something like 185-190 vs 195-200 IIRC. Apparently it helps enough to be noticeable. Not an electric fan issue since my experience was on exactly the same rig w/o any electric fan.

 

[fsmyth]

Just goes to show you that a mechanical fan is never fully disengaged with numbers like that. I've heard reports of some semi fans requiring 50+ horsepower to turn, and being able to move 30,000 cfm. Seems crazy high, but I definitely feel a dip in power when mine kicks in.

Any electric fan setup I've seen usually states it's not meant for towing.

Highly doubt it. We used 25 hp for 8' chiller fans, and that was for conservative industrial.
More like 5-10 hp. for trucks.
<als>

 

[theguruat12]

I believe Robert (RLDSL) installed electric pushers in front of his radiator, and the mechanical fan still on the water pump.

In my truck at least, I'm not sure that the upgrade is worth the hassle just for better A/C at idle. Mine is good enough even at idle that I really don't think I'd do an upgrade. Some other cars though, yes.

 

[Turbo OM617]

The only real benefit to an electric fan is engine responsiveness. For trucks, especially semis, that doesn't matter.

 

[jaluhn83]

Disagree, the main reason you see them in cars is that it allows the fan and engine to be independently located - ie transverse mounted engines. Also allows better control and thus a small increase in fuel economy. That being said, the fuel economy change is much more noticeable in a small high efficiency engine than a truck.

 

[Black dawg]

This is what I want to comment on, and what seems to be brought out by the numbers in the first post; With all that frontal area we have, and he is doing 70mph, theoretically you would not need a fan. But it's obvious from his numbers at 70. and my experience also, that you do need the fan, even at 70 mph. I can't figure it out, it's not like we have small grilles that won't let the air in.

And you also have to be careful, it's a well known fact that lots of junk in the airflow path like aux fans will tend to block the airflow some, so think about it before you add some. With a mechanical fan that pulls so much air, and a little dinky fan that in comparison pulls very little air, it may be going backwards if the little fan blocks some of the air going through.

Back when my truck did NO towing in the winter, I would remove the clutch and fan, in hopes for a little better mpg. It was interesting in the spring how much warmer it would run rolling down the highway with/without the fan.

Another thing I have recently noticed is that not all of the idi fan blades are the same. I was parting a 6.9 truck, and noticed that the blade looked more aggressive than the one on my 7.3 truck. The blade that was on my 7.3 truck made so little noise, that it was hard to tell if the clutch was ever locking up. With the blade off of that 6.9 truck installed on my clutch, there is NO missing when the clutch engages. And I do believe that it is moving lots more air, because my overheating issues have been greatly reduced.

 

[snicklas]

Disagree, the main reason you see them in cars is that it allows the fan and engine to be independently located - ie transverse mounted engines. Also allows better control and thus a small increase in fuel economy. That being said, the fuel economy change is much more noticeable in a small high efficiency engine than a truck.

I also think electric fan is also partially for emissions and greater engine temperature control, more on gassers and some with the A/C. My 2000 P71, with a 4.6 Conventional Mount (RWD) Engine and my Dad's 2012 F-150 with a 5.0 4WD both have electric fans mounted to the radiator. There is no fan mounted to the water pump on either engine. There is actually a ton of space between the engine and the radiator. These fans seem to run much more that I remember the fans running on our older mechanical fanned V-8 Gassers. They also run at a low speed when the A/C is running, to help keep air moving through the condenser. That being said, gasser normally do not produce as much heat as a hard working diesel. On the newer diesel pickups, my 03 and even the 15 6.7's still use a mechanical engine driven fan. Now they have and electric controlled clutch, just like the big truck with air or electrical controlled fans. In the space constraints, I think for a diesel, the engine driven fan is the better choice for enough air movement.

I know on my P71, once it is at normal operating temp, no matter the outside ambient temp, or the load on the engine.... the coolant temp stays fairly constant....... I understand there is more at play in that than just the fun..... but the fan does cycle to help achieve this.

 

[FarmerFrank]

Back when my truck did NO towing in the winter, I would remove the clutch and fan, in hopes for a little better mpg. It was interesting in the spring how much warmer it would run rolling down the highway with/without the fan.

Another thing I have recently noticed is that not all of the idi fan blades are the same. I was parting a 6.9 truck, and noticed that the blade looked more aggressive than the one on my 7.3 truck. The blade that was on my 7.3 truck made so little noise, that it was hard to tell if the clutch was ever locking up. With the blade off of that 6.9 truck installed on my clutch, there is NO missing when the clutch engages. And I do believe that it is moving lots more air, because my overheating issues have been greatly reduced.

Hmmmmm I'm going to have to dig up a 6.9 fan and try it on my truck. Should have one. As soon as I hit a hill with a trailer I watch my temp gauge soar. Usually I'm down to first gear, half throttle and the gauge will bump 240 trying to pull the mountain to get home. Multiple clutches, rads, and other things tried with no prevail.

 

[FORDF250HDXLT]

Hmmmmm I'm going to have to dig up a 6.9 fan and try it on my truck. Should have one. As soon as I hit a hill with a trailer I watch my temp gauge soar. Usually I'm down to first gear, half throttle and the gauge will bump 240 trying to pull the mountain to get home. Multiple clutches, rads, and other things tried with no prevail.

shoot your oil pan with a temp gun.