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Discussion Starter · #1 ·
How many are using electric fans on the radiator?
If so, did you notice better temp regulations?
Did you notice any useable power increase street or trail?
Thanks
 

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i had electric fans and removed them. They didn't move enough air to keep it cooled. i went back to a over sized radiator, fan, and heavy duty fan clutch
 

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thermostat controls the temp, not the fan.
an electric fan will cause the alternator to work more negating any gains from removing the mechanical fan.

electric fans work great in areas where you cant get a square radiator, but our jeeps run great with the oem cooling system
 

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How many are using electric fans on the radiator?
I run electric fan(s) on some of my vehicles but not all. I have run an electric fan on a former TJ, but I haven't yet gotten around to converting my current Jeep to an electric setup.

If so, did you notice better temp regulations?
Jed pointed out that it is the thermostat's job to regulate engine temperature (ie, the thermostat determines the engine's minimum operating temperature), and he is exactly corrrect. However, I believe what you're really asking is if any of us have seen the electric fan do a better job at keeping the engine temp from climbing above the thermostat's set point. In general, most will tell you no. If anybody swapped from a mechanical fan to an electric fan and saw their engine's operating temp go down as a result, I'd say there was a problem with the mechanical fan setup (such as a bad clutch).

Did you notice any useable power increase street or trail?
Converting to an electric setup will reduce parasitic losses, which then results in increased engine power output as well as improved economy. However, this doesn't mean you should start racing Corvettes for their pink slips, nor can you start teasing Geo Metros for being gas hogs. ;)

an electric fan will cause the alternator to work more negating any gains from removing the mechanical fan.
The second half of this statement is entirely, completely, exactly incorrect. Yes, running an electric fan will require greater output from the alternator. However, independent measuring--controlled, repeatable, back-to-back dyno testing--has shown the increased alternator drag from no electric fan to a running electric fan costs an engine only about 1 HP or less. Even the single most efficient clutch fan I've ever seen tested robbed the engine of 8 HP, though most clutch fans typically consume 10-20 HP. The end result? Dumping your clutch fan for an electric setup will net you a significant drop in parasitic losses, and thus an increase in power and efficiency.

Just make sure you choose an electric fan that flows enough air to keep your operating temp in check. ;)
 

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Discussion Starter · #5 ·
If anybody swapped from a mechanical fan to an electric fan and saw their engine's operating temp go down as a result, I'd say there was a problem with the mechanical fan setup (such as a bad clutch).



Converting to an electric setup will reduce parasitic losses, which then results in increased engine power output as well as improved economy.



Just make sure you choose an electric fan that flows enough air to keep your operating temp in check. ;)
I do understand cooling, and know the function of the thermostat - as stated. Never expected lower temp was concerned with the electric system creating enough air flow for adequate heat exchange, so when the thermostat opens cooling is achieved to the setpoint whether 165*, 180*, etc.
Also understand the realities of TRUE HP gain or loss and 8 is a lot.
So information JEEP - TJ specific is what I'm after and what you answered.

I'm a Member of the 150+ Club on Four and 2 Wheels - never had an Eco Machine.

Thanks for your Helpful response.
 

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I ran a Taurus fan for a while when I lived in Los Angeles. No real difference in temps, or performance - just a different sound coming from under the hood. Oh, and the sound of a fan running after turning off the Jeep.

I think the majority opinion here would be that you would get no performance gain. Power saved by not directly spinning the fan is offset by the increased load on the alternator.

YMMV.
 

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How many are using electric fans on the radiator?
If so, did you notice better temp regulations?
Did you notice any useable power increase street or trail?
Thanks
Don't do it. First, there is no such thing as a free lunch, energy wise. You won't pick up power by converting to an electric fan simple because the load that disappears from the serpentine belt just gets transferred over to the alternator which becomes harder to turn whenever the electrical fan is pulling power from it.

Second, I've yet to see a fan that could be mounted to the TJ's radiator that moved as much air as the OE fan does. The TJ's OE cooling system is actually superb as designed, converting to an electric fan would be a downgrade.

When the radiator is functioning as designed, the correct 195 degree thermostat is installed, and the fan clutch is working as designed, the stock cooling system will keep the engine cool on the hottest of days. It has more cooling capacity in reserve than many would understand.

I wheel at least half the time in the desert and in 21 years of wheeling TJs, my engine only overheated once from the thermostat sticking shut. And that wasn't even in a hot area, a stuck thermostat can make any engine overheat.'

Not to mention the bunch of times I've had to help Jeep owners whose engines overheated from something in their aftermarket electric fan system no longer working.
 

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Let's also remember that what a clutch fan pulls on a dyno has absolutely no bearing on real world conditions....

A vehicle sitting stationary running at WOT creats a LOT of heat and the fan clutch stays locked up....
Put the same behicle on the highway cruising 60 mph at 1/4 throttle and thw fan clutch likely won't even engage.

Yes the mech fan CAN take a bunch if power BUT only when it needs to.

While we're at it remember that if it did actually take 8 hp at 5500 rpm it would be taking closer to 3 at 2400 again only IF the engine were working hard enough to produce enough heat to kick it in.
 

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I agree the stock style fan works fine.
Power use, electrics only work when needed, some will shut off above certain speeds, belt drive with a clutch are always turning, but slips at higher RPM so pulls less air/power. That's good on the highway or road, but crawling in low range can lead to over heating. A flex fan is the better option (over a clutch) I think, it works as well as either at low rpm, but still pulls good air at higher RPM.

To me the biggest advantage to an electric fan is that normally you don't need a separate shroud, it's built in and is slimmer than the belt drive style. That can make some maintenance and repairs a lot easier and quicker.
 

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I think the majority opinion here would be ... Power saved by not directly spinning the fan is offset by the increased load on the alternator.
Hey, the majority of humans could agree that the Earth is flat... but such a 'majority opinion' doesn't make their incorrect belief any more correct.

You won't pick up power by converting to an electric fan simple because the load that disappears from the serpentine belt just gets transferred over to the alternator which becomes harder to turn whenever the electrical fan is pulling power from it.
Jerry, you are well-known for offering sage advice on a great variety of Jeep topics, and I have tremendous respect for you because of it. However, this is one instance where you are incorrect. Your claim sounds logical on paper... but repeated, instrumented, scientific testing proves otherwise. Every. Time. Back-to-back dyno testing with an 'unloaded' alternator compared to the same setup but with the alternator powering an electric fan shows a measured power loss of less than 1 horsepower. Maybe it is because alternators are so efficient at making electricity; perhaps the plastic (electric) fans weigh less and thus don't require as much power to turn; maybe there are other factors as well. All I know is, it has been proven again and again that alternator-driven electric fans create much less power loss from an engine compared to a mechanical fan.

When the radiator is functioning as designed, the correct 195 degree thermostat is installed, and the fan clutch is working as designed, the stock cooling system will keep the engine cool on the hottest of days. It has more cooling capacity in reserve than many would understand.
I completely agree with this entire statement.

Not to mention the bunch of times I've had to help Jeep owners whose engines overheated from something in their aftermarket electric fan system no longer working.
On the other side of the coin, I have seen overheated engines on the trail where fan clutches have died. I have also seen mechanical fans get thrown into the radiator, chopping through the core and causing cooling system mayhem. Mechanical fans are no less prone to trail failure than electric ones.

Let's also remember that what a clutch fan pulls on a dyno has absolutely no bearing on real world conditions....

A vehicle sitting stationary running at WOT creats a LOT of heat and the fan clutch stays locked up....
Put the same behicle on the highway cruising 60 mph at 1/4 throttle and thw fan clutch likely won't even engage.

Yes the mech fan CAN take a bunch if power BUT only when it needs to.
Then how do you explain measured power losses (yes, on a dyno) from a mechanical fan that is sitting entirely exposed to free air? In other words, not in a hot engine bay, not behind a hot radiator, but just spinning freely in ambient air? Even when the clutch is not engaged, spinning a mechanical fan still robs significantly more engine power than an alternator powering an electric fan does.
 

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On a Dyno the fan is pulling static air through it
On the interstate the fan is being pushed through the air at speed which actually helps to turn it

I don't build my Jeep to run on a dyno I build my Jeep to run on the road and on the trails

Again Dyno testing has no bearing on real world results. If you want to know what it will do in the real world you have to test it in the real world
 

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Hey, the majority of humans could agree that the Earth is flat... but such a 'majority opinion' doesn't make their incorrect belief any more correct.
I used the word OPINION purposefully. I may not agree with the assertion, but I thought I would warn you of the impending opinion responses.

Frankly, having actually done the conversion, and subsequently returned to stock, I don't think there was enough gain in either cooling- or horse- power to make it worthwhile. It only really adds a new layer of complexity, and there is no value in complexity.
 

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agree with Jerry on this one...there simply is no free lunch. Moving a given amount of air will take a given amount of power/energy, regardless of where it comes from.

To actually increase cooling capacity by switching from the clutch-based fan to an electric one, you would probably need to install a fan that would make your lights dim and your stereo lose its settings when it kicked on...
 

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As for the 'dyno test' proving no 'energy' benefit, there is a massive difference in air flow between moving at 60mph and sitting stationary on a dyno. Real world power consumption will always be different than idealized dyno conditions.
 
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