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Old 04-16-2014, 09:50 AM   #1
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electric fan conversion

i have a 2006 wrangler with a 4.0 L six. I was just wondering if it would be a smart idea to convert to an electric fan. If so what are good fan kits to buy? it also has a K&N intake on it. Any feed back on the fan kit would be much aprreciated

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Old 04-16-2014, 09:56 AM   #2
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No, it's not a good idea to convert to an electric fan. For the most part, it would take a huge electric fan to even come close to the CFM the engine driven fan pulls. The ONLY valid reason to convert to an electric fan is if you're doing deep water crossings where you want to be able to shut the fan off.

I would also get rid of that K&N. First, it's not improving performance since the OE air intake is not restricting your engine's air flow. SOME air intakes are restrictive but the TJ's is not, it can easily flow more air than the engine can consume. Next and more importantly, the K&N is about the worst air filter out there for actually filtering the air. It lets in far more dirt than you'd guess, enough so that I got rid of my K&N many years ago. The added dirt may not be a huge issue for cars that never see dirt roads but it's bad news for a Jeep that gets driven off road where dust gets kicked up.

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Old 04-16-2014, 11:15 AM   #3
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Jerry is correct. Electic fans gain you nothing in the short and long run. Those charts for those cold air devices reflect best case runs and you would never feel the difference, not for the price anyway. About all you'll do is impress the magazine readers.
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Old 04-16-2014, 06:31 PM   #4
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Mine works great and was easy to install. I can't recall the brand. I wired it to a dash switch for water crossing shut off and it works well too. I'm not sure why you mention the intake as it's unrelated to the rest of your post.
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Old 04-17-2014, 08:16 AM   #5
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Listen to Jerry. He has a lot of experience! If you wont listen to him, then listen to me.

I put one in (Flex-a-lite). $200 for no significant benefit whatsoever. I thought maybe I would get a few more horsepower, but even if it's 7HP, you cant tell it. It works, but it was not a wise investment.
Another concern with HP benefit discussion is that the electric fan when running will draw more current, which causes the alternator have more of a load. More load, less HP.

So, go find something else to spend your money on. Or better yet, go somewhere and GO WHEELING! (yes, I'm yelling at the computer monitor)
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Old 04-17-2014, 11:53 PM   #6
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I am cursed with the 2.5L engine and automatic transmission. In my case I did notice a slight increase in power. Now, it can ALMOST get out of its' own way.
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Old 04-18-2014, 12:11 AM   #7
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i am cursed with the 2.5l engine and automatic transmission. In my case i did notice a slight increase in power. Now, it can almost get out of its' own way.
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Old 04-18-2014, 12:17 AM   #8
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I love my k&n can feel a drag if I throw in a paper filter but I have a snorkel. Plus it's paid for itself. It's 14 years old. My engine runs like new at 137,000 miles 14 years k & n filter. ya that's reality. Not a chart. I can make a chart if ya want. electric fans I agree are stupid.
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Old 04-18-2014, 12:32 AM   #9
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I put a black magic fan shroud combo on the Jeep, Why... Because we had a spare at the shop and I wanted to. Did I gain any Hp... Nope. Mileage, maybe .5mpg. Does it cool the jeep, yes. If i had to spend $300 on one would I do it... No
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Old 04-26-2014, 06:17 AM   #10
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I installed the Flex a lite radiator fan combo on an 05 mail jeep 4.0 about 6 months ago no problems yet. the reason being oem rad and fan would not keep engine temp at normal range. but the conditions it is used in are probably not normal 55 miles a day and average 450 to 500 stop and goes.
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Old 04-27-2014, 11:31 AM   #11
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Not sure why krisbman would call bs on my post. I drive the same hill everyday to town. Since putting on the electric fan on my 2.5L I gained 5 mph when topping the hill with no other changes. I can see why it may not make as much difference on a 4.0L but it did on my 2.5L. On another note, the stock fan on my jeep gets 2700cfm. The fan I installed is 3300cfm so am not sure how it was concluded that there isn't as much cooling. Never had a heating problem going from California up to Oregon pulling a trailer.....a lot of second gear 4200rpm hill climbing in 90+ degree weather. Say what you guys want...it works for me.
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Old 07-28-2014, 03:13 PM   #12
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I did some research before dropping the $379.99 on a Flex-A-Lite fan. Conventional wisdom, several websites (including one source who claimed to have dyno'd their XJ's 4.0L) said that removing the mechanical fan and replacing it with an electric one would gain HP and give greater MPG.

After the install, my Jeep is more responsive; not a night-and-day difference, mind you, but more responsive nonetheless. Is it worth it? hmmm.... if I pick up the extra MPG as the site claims (I'll post a link when I get home) it'll pay for itself in a few years. If not, then no.
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Old 07-28-2014, 05:29 PM   #13
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Spal makes a great fan a lot of LS guys use them when they cut weight and ditch the dual fan setup for a single. There should be couple things you need to research first though.

1) How many CFM is required to keep the jeep happy and cool?
2) How you plan on wiring it.
3) What temperature your jeep ideally runs at

Size 16 pull / Part# 2082 - The Fan Man

The spal fan (not sure if you can find it cheaper somewhere else, your job to look) run at 2470CFM and atleast in that link it is $129. They make a kit that is about $47 185FH 1/2\ - The Fan Man that basically runs the fan based on how hot the jeep gets. You would have to see what temp that kit is set to come on at if you have a specific temperature that you are hoping to keep your jeep at. I know my buddies was 180*

Keep in mind if your jeep likes running at 195 (for example) and you get somethign that kicks on at 160*, you could potentially lose gas mileage as you will not allow the truck to get to temperature and you will run a richer mixture. I don't know how Jeeps are mapped and I don't think anyone actually has access to those tables with a tuner, so I couldn't tell you how much that temp change could impact you.

I would then splice into that kit wiring kit though and run a manual fan switch to the inside cab so that you can flip the fan on when you want to on command. I like doing it this way so that you don't have to worry about forgetting to flip the fan on or if someone else takes your car.

Another option you can look into that appears to be a popular and cheap way of doing this is the taurus fans. I've briefly read about them, not sure how well they perform as I havent been able to find their CFM rating yet.

Whether or not it is a good idea depends on the usage of the vehicle- yes you'll free up some horsepower and add a tiny bit of fuel efficiency to your vehicle, but really, to get the full benefit of the fans you would want an electric water pump to go along with it and allow you to bring the truck to ambient temps within a minute or less.
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Old 07-28-2014, 06:50 PM   #14
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The Tarus fan CFM is up there (5.0 Mustang guy here) and is used a lot. CFM is close second to the Mark VIII which I have. There are sites with the CFM ratings.

Now does the Jeep need all that flow, n. And these two fans have a very high current draw. You need a soft start controller.
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Old 07-29-2014, 09:14 AM   #15
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Question It's GONE!

fourwheeler.com was the site claiming gains from the fan swap.... and now that part of the article is missing.... ....so I sent JP Magazine a message....

Quote:
In the 'Jeep 4.0L Myth Busting - True Lies' article, (found here: Jeep 4.0L Myth Busting True Lies - Jp Magazine) Christian Hazel and Pete Trasborg write about replacing the mechanical fan with an electrical fan, and the gain in HP and MPG. The section on the fan swap is now missing. Why? In the article they were in favor of the swap; has that view now changed?
We'll see if I get a response, and I'll post it if I do.
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Old 07-29-2014, 09:29 AM   #16
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fourwheeler.com was the site claiming gains from the fan swap.... and now that part of the article is missing.... ....so I sent JP Magazine a message.... We'll see if I get a response, and I'll post it if I do.
Which im willing to bet was no more than a 5hp increase and in a 3800lb vehicle with an aerodynamic efficiency of a brick your not gonna feel it.
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Old 07-29-2014, 10:39 AM   #17
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There is no free lunch where a fan conversion is concerned. The fan takes energy to turn whether it's driven by an electric motor or by the engine. The electric motor draws more amperes from the alternator which then becomes harder to turn. Yes, alternators and generators require more HP to turn them the more load that is placed on them.
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Old 07-29-2014, 10:42 AM   #18
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There is no free lunch where a fan conversion is concerned. The fan takes energy to turn whether it's driven by an electric motor or by the engine. The electric motor draws more amperes from the alternator which then becomes harder to turn. Yes, alternators and generators require more HP to turn them the more load that is placed on them.
This is very true. I cant remember the conversion but a fella i worked with was super smart about it and said that with the amperage draw it was somewhere in the 3-4hp range if memory serves.
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Old 07-29-2014, 11:33 AM   #19
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There is no free lunch where a fan conversion is concerned. The fan takes energy to turn whether it's driven by an electric motor or by the engine. The electric motor draws more amperes from the alternator which then becomes harder to turn. Yes, alternators and generators require more HP to turn them the more load that is placed on them.
From Which is Better – an Electric or Belt-driven Fan? | Flex-a-lite Blog

An electric fan is the better performance solution, freeing up maximum horsepower and mpg. But its not always the better cooling solution. The full answer to this question is that both electric and belt-driven fans have their place. Which one is better depends largely on the specific application.
All fans consume energy to spin. Belt-driven fans use mechanical energy directly from the engine. Electric fans rely on electric energy from the battery and charging system. But in cooling, what makes a good fan is optimum airflow for cooling with minimum energy consumption (for maximum engine power and fuel economy).

Electric Fans

An electric fan completely removes the mechanical load of spinning the fan from the engine. It places an additional draw on the electrical system, but this is a more efficient means of spinning a fan, and it has a smaller impact on engine drag. Between the two types of fans, an electric fan offers an improvement in power delivered to the wheels.

____________________________________________

Also consider when the vehicle is in motion the majorty of cooling comes from forced air flow of the vehicle. If the coolant is below the turn on setpoint of the fan, the fan will be off (or maybe off depending on the controller). A clutch fan is always turning and will increase with engine RPM.
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Old 07-29-2014, 12:22 PM   #20
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Also consider when the vehicle is in motion the majorty of cooling comes from forced air flow of the vehicle. If the coolant is below the turn on setpoint of the fan, the fan will be off (or maybe off depending on the controller). A clutch fan is always turning and will increase with engine RPM.
Bingo! and all very good points in the above article to.

Like I also said to, if you cool the vehicle too much, it will put the computer into a more fuel and more timing portion of its map which could be good or bad based on what you are trying to achieve
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Old 07-29-2014, 12:30 PM   #21
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Bingo! and all very good points in the above article to.

Like I also said to, if you cool the vehicle too much, it will put the computer into a more fuel and more timing portion of its map which could be good or bad based on what you are trying to achieve
There coolant thermostat will be what prevents subcooling. The fan controller should be correctly set based on the thermostat used.
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Old 07-29-2014, 12:35 PM   #22
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An electric fan completely removes the mechanical load of spinning the fan from the engine. It places an additional draw on the electrical system, but this is a more efficient means of spinning a fan, and it has a smaller impact on engine drag. Between the two types of fans, an electric fan offers an improvement in power delivered to the wheels.

____________________________________________

Also consider when the vehicle is in motion the majorty of cooling comes from forced air flow of the vehicle. If the coolant is below the turn on setpoint of the fan, the fan will be off (or maybe off depending on the controller). A clutch fan is always turning and will increase with engine RPM.

at what CFM? mechanical fans draw more air on average


to the second part, isnt that the function of the clutch, to release the fan connection to the engine when it is cooled to a certain point? therefore it isnt always putting more load on the engine but when needed it pulls more cfm than your standard fan
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Old 07-29-2014, 01:05 PM   #23
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at what CFM? mechanical fans draw more air on average
Depends on the electric fan. A good electric fan can flow a lot more than a mechanical. There are no available numbers for a stock fan CFM. Assume a stock mechanical/clutch is designed around the cooling needs of an engine. From the below sites A 6 cyl in general requires 2,000 CFM (2500 for a 8 cyl)


The Mark VIII fan will move 4300 CFM at low speed and 5000 on high


Note this is NOT TJ data.


From the Griffin radiator site Radiator Cooling : Griffinrad.com | Frequently Asked Questions Tips to help you

3. Thou shall use an electric fan.
Rule of thumb. Only choose a mechanical fan over an electric fan if it's your farm tractor. An electric fan is preferred because when you need a fan the most (at idle or cruising speeds) an electric fan is delivering maximum air independent of engine RPM's. Fans that move 2000-2300 CFM's are worth the investment.

(this is typically when a vehicle need maximum cooling. When moving at speed, the forced air movement provides much of the cooling)


From the Flex A Lite site, How to Choose an Electric Fan | Flex-a-lite Blog

A 6 cyl in general requires 2,000 CFM (2500 for a 8 cyl)



Someone's independent testing (Chevelle) data for mechanical engine drive fans Dyno testing on fans, alternators and oil.....all here!

FAN TYPE IDLE (800) IDLE (1600)
__________________________________________________ ___________________

BB18 1680 2355

BB18C(heat) 1580 2205

BB18C(COOL) 1104 1400

SKIPPER 1503 2020

FLEX 17 1420 1814

Here is some electric fan data Found a few stock fan.. CFM comparisons ..cheap cooling alternatives..? - Yellow Bullet Forums

Alternator Powered

LS1 FAN SHROUD
1 fan turned on - 5100 cfm
2 fans on - 10500cfm

LT1 FAN SHROUD
1 fan turned on - 5200 cfm
2 fans on - 9500 cfm

Dodge Fan (both fans are always on - 2 speed)
Slow speed - 4200 cfm
High Speed 10400 cfm

Ford Taurus (1 fan two speed)
Slow speed - 3200 CFM
High speed - 6000 CFM


The above items and other data I saw on various web sites is pretty much in agreement. A typical 6, 8 cyl requires 2000 - 2500 cfm for cooling. I would assume the TJ stock fan is in line with the 6 cyl cfm needs and somewhere in the 2000+ cfm range.

The data for the better electric fans (Viper, Taurus, Mark VIII, LS1) are capable of flowing WAY over 2000 cfm.

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to the second part, isnt that the function of the clutch, to release the fan connection to the engine when it is cooled to a certain point? therefore it isnt always putting more load on the engine but when needed it pulls more cfm than your standard fan
Yes a viscous fluid clutch does tighten/loosen with temperature but it is always turning and has some amount of drag. An electric fan can be off.
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Old 07-29-2014, 01:10 PM   #24
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what are the power draws of those electric fans?
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Old 07-29-2014, 02:22 PM   #25
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From Which is Better €“ an Electric or Belt-driven Fan? | Flex-a-lite Blog

An electric fan is the better performance solution, freeing up maximum horsepower and mpg. But it’s not always the better cooling solution. The full answer to this question is that both electric and belt-driven fans have their place. Which one is better depends largely on the specific application.
All fans consume energy to spin. Belt-driven fans use mechanical energy directly from the engine. Electric fans rely on electric energy from the battery and charging system. But in cooling, what makes a good fan is optimum airflow for cooling with minimum energy consumption (for maximum engine power and fuel economy).

Electric Fans

An electric fan completely removes the mechanical load of spinning the fan from the engine. It places an additional draw on the electrical system, but this is a more efficient means of spinning a fan, and it has a smaller impact on engine drag. Between the two types of fans, an electric fan offers an improvement in power delivered to the wheels.

____________________________________________

Also consider when the vehicle is in motion the majorty of cooling comes from forced air flow of the vehicle. If the coolant is below the turn on setpoint of the fan, the fan will be off (or maybe off depending on the controller). A clutch fan is always turning and will increase with engine RPM.
So someone at Flex-A-Lite figured out how to get around conservation of energy? That sentence needs some serious clarification. I understand what they are trying to convey, but is extremely misleading to people who don't know better.

To flow the same amount of air an electric fan WILL require more HP to turn than a mechanical fan. There's no getting around that unless someone has made a 100% efficient alternator and fan, which would still, at best, require the same amount of energy. Never less.
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Old 07-29-2014, 03:55 PM   #26
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To flow the same amount of air an electric fan WILL require more HP to turn than a mechanical fan. There's no getting around that unless someone has made a 100% efficient alternator and fan, which would still, at best, require the same amount of energy. Never less.
Dig up some information to prove that.
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Old 07-29-2014, 04:08 PM   #27
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where do you think you will get free power from? the more power you draw, the more strain it puts on your alt

unless you figured out how to create perpetual motion
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Old 07-29-2014, 04:52 PM   #28
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To flow the same amount of air an electric fan WILL require more HP to turn than a mechanical fan. There's no getting around that unless someone has made a 100% efficient alternator and fan, which would still, at best, require the same amount of energy. Never less.
How is this possible? I do not understand how the draw on the alternator (and the resulting load on the engine) and the amount of HP required to turn the a mechanical fan are equal.

Also, if the energy usage is equal, than why are cars manufactured today all (as far as I know) have electric fans?


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where do you think you will get free power from? the more power you draw, the more strain it puts on your alt

unless you figured out how to create perpetual motion
No one is saying it is "free" to operate.
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Old 07-29-2014, 05:21 PM   #29
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well the flexilite fan designed for the TJ draws 18a, that certainly isnt a small amount

how many modern vehicles have a square radiator?
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Old 07-29-2014, 05:31 PM   #30
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How is this possible? I do not understand how the draw on the alternator (and the resulting load on the engine) and the amount of HP required to turn the a mechanical fan are equal.
This is relatively simplified, however, if you want to move X amount of air it requires Y amount of work and never less. If everything were 100% efficient you could very easily calculate the amount of work needed and in both cases of electric and mechanical fan it would be exactly the same amount of work required.

However things are not 100% efficient. Blade design for example plays a role, but for now lets assume both electric fan and mechanical fan are the same. With an electric fan you are converting work done by the engine into electricity, then back into mechanical work. These conversions are inefficient and you lose energy (as heat). A mechanical fan however does not go through such conversions. Therefore to move the same amount of air the electric fan requires a bit more energy to overcome inefficiencies.

Quote:
Also, if the energy usage is equal, than why are cars manufactured today all (as far as I know) have electric fans?


No one is saying it is "free" to operate.
The benefit of electric fans is they can be completely turned off. Although mechanical fans have clutches nowadays, there still some parasitic loss. Because of this there are some efficiency gains to be had. For manufacturers even the tiniest bit counts on the scale of millions of vehicles. There really are a bunch of variables to consider though and both have pros/cons.

Design plays a role. Lots of vehicles are designed in such a way (usually for looks) that a mechanical fan is impossible. Or maybe its fwd car with a sideways mounted engine.

Mechanical fans do, in general, have the ability to pull more air, although are restricted by engine RPM where electric fans aren't.

At the end of the day, and to my main point, electric fans aren't some magical devices that can move more air for less energy required. Stating that it's more efficient to spin an electric fan and that it requires less drag on the engine is misleading. If the fan is spinning and putting less drag on the engine its not pulling as much air, it's really that simple.

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