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electric fan conversion

46K views 66 replies 22 participants last post by  Beastmaster 
#1 ·
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
 
#2 ·
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.
 
#3 ·
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.
 
#5 ·
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)
 
#8 ·
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.
 
#10 ·
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.
 
#11 ·
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.
 
#12 · (Edited)
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.
 
#13 ·
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.
 
#14 ·
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.
 
#15 ·
It's GONE!

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

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.
 
#16 ·
fourwheeler.com was the site claiming gains from the fan swap.... and now that part of the article is missing.... :confused: ....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.
 
#17 ·
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.
 
#37 ·
actually, I take that back...you aren't entirely wrong. I do believe you can run on alternator power only once the car is running, but you have it backwards, you won't run more than a few minutes

I also don't suggest that you remove your battery while the car is running to test your theory unless you like fried electronics
 
#39 · (Edited)
Modern 3 wire Alternators require around 12.6 volts to energize the coils and supply power. If you unhook the battery while its running, the jeep will die. Try it yourself if you do not agree. Be prepared for voltage spikes and the possible damage that could occur.

Yes you can run a car for a pretty long distance with no alternator. The jeep I'm working on for a friend had a bad alternator and he drove it around for nearly a week with the same battery before it finally died. Although in this case the only thing pulling power was the coil at around 5 amps. Think about it, how long can your car battery keep your headlights on? Mine has easily lasted 4 hours and those pull on average 9-10 amps or so. If an ignition coil pulls 5-6 amps and maybe another few amps for random electronics, you should have no problem driving a car with a healthy battery at least an hour or two without a working alternator.

Freeskier explained this nicely but because you are still talking about it:

Nothing is 100% efficient. If it were, our worldwide energy crisis would be solved. The electric fan needs power to run so it pulls the power from the battery, which pulls the power from the alternator, which creates more drag on the engine. If the alternator, battery, and fan motor were 100% efficient, an electric fan would use the same amount of energy as a mechanical fan. Unfortunately energy is lost (mostly in the release of heat) and the whole system ends up being less efficient. Now if you had solar panels on your roof that powered your fan that's another story...
 
#40 · (Edited)
I live in Wyoming, we have real mountains around here where the bottom of the hill is at 7000ft asl, and I have a 2.5 / 5spd. I switched from mechanical to electric and there is a real noticeable difference. That's the bottom line, I can pull hills at a higher consistent speed with the electrical than I can with the mechanical and I will invite anyone on this forum to come here and experience it for them self (I have the mechanical fan still and its easy to bolt and unbolt and unplug a wire, dont take my word for it, come see). Yes, the alternator works a little harder from the amp draw of the fan, but not as hard as lights and a stereo pull on it. I don't use a thermostat, I do have a kill switch, but other than that it's always on 100%.

Aside from the power advantage in my little 4 cyl, I understand some people live in areas with actual traffic, I don't, but I don't have a DD either, my Jeep spends a lot of time at low speed and low RPM in tight places with little to no natural air flow (ie; canyons and washes) and without the electric fan running at high rpm while the engine is at low rpm the temps run a little hotter, nothing to worry about, before or after, but a little hotter.

If you havent ever run an electric fan yourself, then you have no basis for a personal opinion, having no personal experience, yeah yeah, I know, same old bs, a friend of a friend has a sister whos boyfriends uncle had one and yadda yadda yadda. Unless YOU have run both mechanical and electric in the same low powered vehicle in the same conditions then I will say you have no real experience and shouldnt be offering speculative opinions based on nothing but what you think is logical.

Electric fans work for the 2.5, that's a simple fact.
 
#41 ·
All right, this may ramble.... I am rereading/rethinking and re-researching... and typing as I do....

One thing I keep reading from some of the anti-electric fan side is a misrepresentation of the other argument; that there is a claim that the electric fan is 100% efficient, is free to operate, etc.
None of the electric fan backers are stating that. By exaggerating someone else's argument, it's much easier to present your own position as being reasonable, but this kind of statement serves to undermine honest rational debate.

I also continue to see statements similar to "electric fans don't cool as well as the TJs factory fan does," but there isn't any temperature readings to back this up. From what I am reading, this is an “old-school” mentality. The newer blade and shroud designs allow for an increased airflow capacity to adequately cool. Also, I can not find what the CFM of the stock fan is; I guess a CFM rating would have to be based on a constant RPM and a direct drive fan doesn't give that option. I would think somewhere there would be a rating “This fan has a CFM of X @ Y RPM (idling speed, cruising speed, etc.)” but I can't find it. My Flex-a-Lite has a 3300 CFM rating, and I know I can feel the air flow difference over my stock mechanical fan. Was my clutch fan operating correctly? I don't know.

I had posed the question, if the energy usage is equal (or worse) between mechanical and electric, than why do the cars being manufactured today all have electric fans? I think freeskier's explanation is solid, but it still left me with some doubts. So I looked into the only vehicle I know/care about, Jeep.
JK's (all?) have electric fans, and I have not seen of any aftermarket manufacturers rushing a "mechanical fan upgrade" to the market to replace them. I searched online; I found one JK owner who did this mod and in the end (the last post anyway,) he ends up running both fans. I didn't quite follow his logic for doing so, best-of-both-worlds scenario I guess, but his write up is worth a read.

Then I looked again at the Jeep's alternator. The argument is that the electrical fan puts a greater load on the alternator and thus on the engine than running the factory clutch fan. This is
likely false, at best unprovable. There is a mechanical drag (bearing friction) and an electrical drag. The electrical drag will be proportional to the load that the electrical system demands on it. My alternator is rated at 117 amps. My Flex-a-Lite fan has a starting load of < 40 amps, and a running draw of 18 amps. For comparison, my headlights and fog lights have a draw of about 5 amps each, so a 20 amp draw when I'm cruising down the road at night. If my math is correct (18 A X 12.8 V = 230.4 W & 1 HP = 745.69 W), it takes 0.31 HP to operate the electric fan, and you have to consider the fan is not running all the time. The loss of HP is miniscule.

Overall then, there is a greater parasitic loss with mechanical fans than with electrical fans. There just isn't any hard data that suggests otherwise.



The fan is $379.99. Everything I've read on a electric fan conversion says I can reasonably expect a 5% - 10% increase in MPG. If the TJ gets 18 MPG now, a 5% gain will push it to 18.9 MPG, I'll round it to 19 MPG, 10% gain would be 20 MPG. I drove the TJ 15,582 miles last year. Using $3.75 a gallon for gas prices:
@ 18 MPG, I would have used 866 gallons, at a cost of $3,247.50.
@ 19 MPG, I would have used 820 gallons, at a cost of $3,075.00. I would have saved $172.50.
@ 20 MPG, I would have used 780 gallons, at a cost of $2,925.00. I would have saved $322.50.

I can see no reason not to do this, based on my Jeep being a DD. Your cooling needs may be different. This is a well balanced read: Which is Better – an Electric or Belt-driven Fan?
 
#44 ·
I should clarify I don't think electric fans can cool well enough, however for a Jeep I do believe they are cost prohibitive to get have a quality set up that will be as reliable as the stock mechanical fan and clutch. I'm at 130k+ miles on the factory clutch and the Jeep has never overheated, I've never even seen it higher than 215*. A new clutch is cheap. As far as power gains I can't say, but frankly I don't care, not an issue with proper gears and the 4.0.

All right, this may ramble.... I am rereading/rethinking and re-researching... and typing as I do....

One thing I keep reading from some of the anti-electric fan side is a misrepresentation of the other argument; that there is a claim that the electric fan is 100% efficient, is free to operate, etc.
None of the electric fan backers are stating that. By exaggerating someone else's argument, it's much easier to present your own position as being reasonable, but this kind of statement serves to undermine honest rational debate.


No, they don't say that but it doesn't make their statements any less misleading. They use statements like "more efficient to spin" that are vague and allow the customer to make their own, and often incorrect, conclusions about how it works.

I also continue to see statements similar to "electric fans don't cool as well as the TJs factory fan does," but there isn't any temperature readings to back this up. From what I am reading, this is an “old-school” mentality. The newer blade and shroud designs allow for an increased airflow capacity to adequately cool. Also, I can not find what the CFM of the stock fan is; I guess a CFM rating would have to be based on a constant RPM and a direct drive fan doesn't give that option. I would think somewhere there would be a rating “This fan has a CFM of X @ Y RPM (idling speed, cruising speed, etc.)” but I can't find it. My Flex-a-Lite has a 3300 CFM rating, and I know I can feel the air flow difference over my stock mechanical fan. Was my clutch fan operating correctly? I don't know.
It is hard to pin down a CFM rating on the mechanical fan because it depends on engine RPM AND how locked up the clutch is. I can guarantee you Chrysler has numbers for it, but they are buried in engineering specs/documents. I've seen estimates though in the 6000 CFM range at higher RPM. Really just the size difference should clue you into the fact that mechanical fans can pull more air.

I'm actually surprised no one has tried to test the stock fan. Wouldn't be hard with a flow meter to get an idea. You could easily trick the fan clutch into locking up then test at various RPMs for max flow.

I had posed the question, if the energy usage is equal (or worse) between mechanical and electric, than why do the cars being manufactured today all have electric fans? I think freeskier's explanation is solid, but it still left me with some doubts. So I looked into the only vehicle I know/care about, Jeep.
JK's (all?) have electric fans, and I have not seen of any aftermarket manufacturers rushing a "mechanical fan upgrade" to the market to replace them. I searched online; I found one JK owner who did this mod and in the end (the last post anyway,) he ends up running both fans. I didn't quite follow his logic for doing so, best-of-both-worlds scenario I guess, but his write up is worth a read.


Like I said lots of variables to consider when you're engineering the system and there are efficiency gains to be had. When manufacturers have to pay taxes based on how efficient their fleet is, even the tiniest of improvements translates into millions saved. Also as technology progresses engines get more efficient, they don't produce as much heat, and cooling system requirements are lower.

However, if you've ever wheeled with groups of varying vehicles, it's obvious who has electric fans. They are always full blast and sound like jet engines.

Then I looked again at the Jeep's alternator. The argument is that the electrical fan puts a greater load on the alternator and thus on the engine than running the factory clutch fan. This is
likely false, at best unprovable. There is a mechanical drag (bearing friction) and an electrical drag. The electrical drag will be proportional to the load that the electrical system demands on it. My alternator is rated at 117 amps. My Flex-a-Lite fan has a starting load of < 40 amps, and a running draw of 18 amps. For comparison, my headlights and fog lights have a draw of about 5 amps each, so a 20 amp draw when I'm cruising down the road at night. If my math is correct (18 A X 12.8 V = 230.4 W & 1 HP = 745.69 W), it takes 0.31 HP to operate the electric fan, and you have to consider the fan is not running all the time. The loss of HP is miniscule.

Overall then, there is a greater parasitic loss with mechanical fans than with electrical fans. There just isn't any hard data that suggests otherwise.



The fan is $379.99. Everything I've read on a electric fan conversion says I can reasonably expect a 5% - 10% increase in MPG. If the TJ gets 18 MPG now, a 5% gain will push it to 18.9 MPG, I'll round it to 19 MPG, 10% gain would be 20 MPG. I drove the TJ 15,582 miles last year. Using $3.75 a gallon for gas prices:
@ 18 MPG, I would have used 866 gallons, at a cost of $3,247.50.
@ 19 MPG, I would have used 820 gallons, at a cost of $3,075.00. I would have saved $172.50.
@ 20 MPG, I would have used 780 gallons, at a cost of $2,925.00. I would have saved $322.50.

I can see no reason not to do this, based on my Jeep being a DD. Your cooling needs may be different. This is a well balanced read: Which is Better – an Electric or Belt-driven Fan?
If you can see those savings that's great. Personally I'm doing good to put 2000 miles a year on the Jeep.
 
#43 ·
I did the Electric Fan conversion, mine at max is rated at 3300 CFM. That is REGARDLESS of engine RPM's. I wired the fan to run off a thermostat or I can bypass the thermostat and run the fan on HIGH. This is very beneficial when I'm rock crawling and my RPMs are extremely low. The E-Fan shroud completely encompasses the radiator pulling air through the whole thing.
In the end I've never seen the anti E fan crowd produce FACT based CFM's for the mechanical fan. And the argument that the E fan doesn't cool as well...then WHY do the JK's come with an E fan? I don't see JK owners starting thread after thread about cooling issues.
It comes down to personal choice, do what you want to your rig.
 
#50 ·
I can't remember now- you'd need to contact them.

$129 for the fan
Size 16 pull / Part# 2082 - The Fan Man

$47 for the controller
185FH 1/2\ - The Fan Man

But that being said, I know someone mentioned the Taurus fan before and I did a tad more research on it, and it seems like a lot of other guys are using them to with great results...chevy/Ford guys etc. At $40 for the fan, I see that mod in my very near future.
 
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