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Old 10-08-2005, 01:38 PM   #1
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Flex Fan vs Electric??

As horsepower is the key I'm thinking about removing the clutch fan and going to an electric fan setup for cooling. I know about the woos of the electric fan stopping so the real question is.... Has anyone done this? What benefit did you see? On paper it looks like an economy booster. Where did you get yours? Is it worth the time/money to swap?
Thanks for the opinions.
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Old 10-08-2005, 02:49 PM   #2
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Not on a MH, but on my tow vehicle which has a 455 Pontiac engine, I swapped out the radiator for a new aluminum unit and found that helped for cooling but not enough so switched to an electric fan. Zircon, 3,300 CFM, and that brought the temp down another 10 degrees. No problems but I am always just a tad concerned about the electric fan going away on me and being stuck, but so far not a problem. I have not noticed a difference in available power as I've already got enough torque to tow down the road and up most hills without having to go into the secondaries or downshift. The electric fan is noisier outside the vehicle but not a lot.

I based the decision to make the two changes based on new cars like my 740i all having this system and no cooling problems. If the high end manufacturers trust it and have tested it to the n'th degree I felt it was worth the change. Several of our friends who also tow have done the same and although no one has indicated a power improvement it sure has made cooling a non-issue with our classic tow vehicles. As a note I will likely replace the fan this winter, not because it's not working, but I am thinking I might pick up the Flex-a-lite twin fan set up, that way I should always have at least one if for some reason one goes away. Barry
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Old 10-08-2005, 06:32 PM   #3
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If you are really into technical...

You could do what many OEM auto manufacturers now do. Install two electric fans. One kicks on at a temp, usually 200 degrees, and the second will kick on at around 215. This will do several things. First, it will reduce the outside noise around the front of your motor home. Second, it will help give faster warm-ups, although that is usually not a problem for MoHo's. Third, it will reduce strain on your alternator, and your fan motors will last longer, because they are only running when needed, not all the time. Also, with two fans operating independently, you have a bit of a security blanket if one goes out.
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Old 10-08-2005, 09:06 PM   #4
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I like the idea of two fans and staggering the temperature they kick in at is a great idea. Thanks, I will definitely be including that trick in my swap this winter.
Barry
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Old 10-08-2005, 09:20 PM   #5
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I like the idea of two fans and staggering the temperature they kick in at is a great idea. Thanks, I will definitely be including that trick in my swap this winter.
Barry
You can also set up one of the fans to kick on when you turn on the dash A/C.
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Old 10-09-2005, 10:00 AM   #6
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If power is your prime concern I don't think there will be any gains converting to electric fans. It is going to take the same amount of power to cool be it transferred from the crankshaft via the belt or indirectly from the alternator. Large electric fans capable of cooling the system will draw ~20 amps each, a couple will put a pretty good load on a stock alternator (before you consider the other loads of the motor home). You probably should consider upgrading if you do this.

Setting 2 fans up to kick on at staggered temperatures is going to take some planning. Newer vehicles use the computer so they can do it with one input. About the easiest option I see is to use switches. There are ports about the middle of each head, there may or not be a port in the intake manifold. You are going to need 3 ports to control the 2 fans and retain your temperature gauge sender. Using a 'T' is an option but I don't like them for temparature senders. The end of the probe isn't in the coolant flow and gives a poor indication of the actual temperature. Space for the 'T' is another consideration, and accessability once it is installled. You could use external switches that mount on the radiator. I am not a fan of these either, I like to operate off the acutal coolant temperature not transferred indications.

Mounting the fans is another consideration. I hate the thru the radiator clips that come with most electric fan kits, they are nothing but future trouble. Radiators are fragile enough without hanging a fan or two off the core. You will need to build some type of support to hold them in a relatively hard to work space.

I have heard a lot of complaints about the noise the fan makes when the clutch engages, it sounds like a jet taking off or the trans is downshifting. This is the amount of air you need to move to cool these, the cooling system is huge compared to the little 4 and 6 cylinder engines we have become used to. You are going to have to move the same amount of air with electric fans in order to effectively cool the engine.

The clutch fan runs very little actually, mine runs in traffic and on the ramp when coming off the expressway. Considering the amount of time these spend in stop and go traffic and the amount on an expressway most cooling is from airflow from the vehicle movement. If the fan is running a lot on the expressway it would be better to look at the overall cooling system condition or some ducting to direct the air through the radiator. Not to discourage you, but if it takes 4000 cfm to cool the engine you are going to have to still move that much air from either power source. You are not using a huge amount of power in the first place, anything you save is going to be minimal for the expense and amount of work it takes.
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Old 10-09-2005, 11:17 AM   #7
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John, I have done this, in a way. I had one electric fan set up to come one when the engine got too warm, and a second to come on when I turned on the A/C. This was because of an engine swap, installing a 5.0 V8 in a Ranger, and had no room for a fan clutch. I installed both fans on the outside of the radiator/condensor assembly, between the condensor and the grille of the truck.
Of course, now Ford then offered the 5.0 in the Exploreer, which is/was the same platform asa the Ranger, but that was not an option when I did this transplant.
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Old 10-09-2005, 01:19 PM   #8
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just a bit of trivia, new chevrolet light duty pickups with V 8s no longer have a belt driven fan. just electrics.

you can buy fan clutches with various temp settings, get to know your gm parts guy. you may be able to find a happy medium between cooling and performance.

john has some good points about air flow, the natural breeze does way more than any fan can at speed. case in point, my snow plow truck can over heat in 20 degree weather on the highway if it wern't for the lower temp fan clutch i put in it. all because the airflow is blocked by the blade.

my 4600 international at work uses a electric fan clutch, possibly the best solution. the computer can call for cooling if the engine is cold but the ac needs the air flow.

john
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Old 10-09-2005, 01:37 PM   #9
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Interesting input all around guys. My consideration was the drag on the engine driving the fan. I've got a very large alternator but the lower temp clutch makes sense too.
I'm trying to find the best MPG and working all the angles to get there.
My old Champion had an air dam built inside the front cowling to keep the flow of air at speed going thru the rad instead of down in front ... it had quite a bit of room in front of the rad.
Next week when we do the carb work I'm going to recycle my antifreeze and reduce the concentration some. Keeping cool is, in my mind a great way to extend the life of oil and engine/transmission.
While we're talking cooling.. has anyone looked at the frame mounted tranny cooler from Summit??
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Old 10-09-2005, 01:50 PM   #10
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Quote:
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While we're talking cooling.. has anyone looked at the frame mounted tranny cooler from Summit??
Yes. It is mainly for vehicles with no room for a normal transmission cooler. A better choice can be found down the page, with one that has a small fan that turns on if the fluid gets too hot. Of course, if you put all these fans on your coach, you won't need a transmission, the fans will blow you down the road...
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