Looks like my fan clutch needs to be replaced and would like to know if anyone has changed over to electric fans? is it a good/bad idea? i was thinking about 1 pushing fan for the ac. and 2 pulling fans for the radiator, of those two have them set at different temps. thanks for any help.

 

If you have to carry or pull any kind of load, then on a hill the electrics cannot keep up with demand. The engine driven clutch fan moves a LOT more air when it's really needed.
Personally I would never even consider converting to electric fans.

 

I've seen electric fans on OTR trucks that are 24" diamater and move more than 10,000 cfm each that are recommended for GVW's up to 80,000

I think if you want to go electric on your truck then do it. Flex a lite has recently released this: http://www.flex-a-lite.com/auto/html/ford-diesel.html that should take care of you nicely.

Note that they do recommend an 18,000 pound CGVW limit, so if you spend most of your time heavily loaded, you may want to stick with the stock clutch fan or find a custom unit that can move more air. Look around on this site to see the big boys http://www.electricfanengineering.com/

 

Check with your nearest International dealer about the Horton EC450 electric fan clutch for the T444E (replaces existing fan clutch). I never got around to attempting to make the purchase.

 

Yeah...that looks pretty good too. Lets you keep the stock fan. http://www.hortoninc.com/products/products.asp

 

I suppose it would work ok, but honestly, I'm skeptical that such a system would be able to keep up as well as a belt driven fan mounted on the engine when pulling a heavy load up a steep hill.
The biggest concern in my mind is the alternators ability to keep up with demand. A dedicated secondary alternator would be good.

 

Per the specs, it only draws 4 amps when engaged, none when disengaged. It works with thermostatic switches so it's only engaged when coolant or A/C needs it. Advantage would be that it doesn't have a residual effect when not engaged. Would still load the engine just like the viscous clutch when hot.

 

You might be comparing apples and oranges as it were....


He's talking about an electric fan CLUTCH not an electric MOTOR powered fan. (although the first post referred to an "Electric Fan" (electric motor)


Fan manufacturers frequently say you can save engine power (up to 15hp )by switching to electric fans.(MORE on B I G trucks) http://www.highbeam.com/library/docFree.asp?DOCID=1G1:57044400

This is of course is referring to using a direct powered fan(not a thermally operated clutch type fan) vs an electric motor operated fan in a light duty application.

You're right. it's not possible to have an electric motor operated fan that can produce as much power as a belt driven fan.


If you wanted to operate a 15hp electric motor on a 14v system it would require a lot of current!!
1hp = 746W (or 0.746KW)

so lets see.....1000w at 14v.....Watts = Volts x Amps.......14v x72A=approx 1000w .....72 AMPS!

if 746w=1hp then 15hp =approx 11kw 11,000 Watts!!


everybody follow so far?


Now 11kw at 14v would require almost 800A !!! Anybody got an 800 AMP altenator? anybody have a 400A alt?(7.5hp) 200A?(~4hp)


So if that engine requires a 15 hp fan to cool it on that LONG pull, There is NO electric motor driven fan that will do it......and NO altenator that will produce enough AMPS to run it.


Now if you want to remove that viscous clutch and replace it with an electric clutch....Well those are available. same sort of clutch that you use turning on and off your A/C compressor. They seem to last quite a while. They do fail though as do the thermal clutches.


Electric fans work great on light duty applications. .....going down the road, flat.....you don't even need a fan.

Flex-a-lite has one for tow vehicles....they're something like $500-600

This model draws around 36A , 14v x 36A=~500w or about 0.7 hp .... not much.



[This from Flex-a-lite]: Electric fans are not recommended for primary diesel engine cooling when the combined gross vehicle weight (CGVW) exceeds 18,000 pounds (truck, trailer and load)


Regards,


Rick

 

Yeah, that's what I was thinking. You would need a HUGE alternator to keep up with that. If it's just a big electric clutch on a belt driven fan - I don't see the point. You have to put a load on the alternator to engage it, where the fluid drive on the old design uses no current at all. I conced that there is no drag at all when the electric one is off so there is a savings there.
More power to you people who want to get that setup.

 

keep your factory fan. electric dosnt work on our rigs. i ran one for a while and liked the extra power and cooler ac. but towing is a no. my gcwr usually is from 18-26k 5 days a week.

 

The additional load on the alternator wouldn't be significant for an electromagnetic clutch..... we're only talking 4 or 5 amps. (only 60w or so). They also can be designed to carry pretty good loads...

For example, the mower deck on my Yanmar diesel ( John Deere) powered 24hp front mounted mower is powered with an electromagnetic clutch. I'll bet it requires at least 15hp to spin those 3 big blades on the 5 foot deck when going thru the high grass! There's 2 v-belts on the clutch/PTO.



The viscous clutches do have *some* loss actually. they do slip a little when running and when they're supposed to be disconnected they don't fully disconnect....so there's some loss.




Here's some info from that previous article: https://www.ford-trucks.com/lc/lc.ph...1G1%3A57044400



Fan Drive Design

Before the availability of the on/off fan drive, diesel engine cooling fans were direct drive, with the fan engaged 100 percent of the time, regardless of engine temperature or operating conditions. Cooling fans on a diesel truck engine can consume from 16 hp to as much as 41 hp, depending on engine size and fan configuration. A direct fan drive contributes measurably to fuel consumption. Continuous radiator cooling resulted in wide variations in coolant temperature with changes in load, road conditions and weather. A properly operating fan drive minimizes fan "on" time and extends radiator life.

Diesel truck fan drive technology has evolved over the past several decades, from direct drive to viscous drives, then to on/off fan drives.

Viscous Fan Drives

Viscous fan drives are used to reduce the fan load when cooling is not required, and thereby lessen power requirements and related fuel demands. A viscous fan drive offers an improvement in efficiency over direct drive fan cooling. This hub-mounted, fluid-coupled device contains a hydraulic turbine using a viscous silicone fluid to transfer energy from driving element to driven element.

Typically, a bi-metallic element on the front of the viscous drive senses the temperature of air passing through the radiator and operates a valve to control the silicone transfer fluid, thus effecting fan engagement and disengagement. The fan drive is not controlled directly by engine temperature but indirectly by sensing the temperature of cooling air passing through the radiator.

The hydraulic nature of a viscous drive prevents it from achieving fully on or fully off operation. Consequently, in the disengaged mode, the fan continues to operate at speeds as high as 45 percent of the fully engaged rate, usually between 650 to 1000 rpm.

In the engaged mode the slippage (fluid shear) common to the viscous drive's liquid coupling restricts fan speed and associated cooling capacity by approximately 5 to 10 percent. Figure 1 shows the typical operating range of a viscous drive compared to the wider range of engine speeds, taking into account both parasitic drag (partial engagement) and fluid shear (slippage).

The partial engagement or parasitic drag of a viscous drive can contribute to engine overcooling, resulting in unnecessary fuel consumption. For example, with a truck engine speed of 1400 rpm, an average vehicle speed of 50 mph and yearly travel distance of 30,000 miles, a viscous drive consuming 0.5 hp (0.4 kW) in the off mode burns approximately 48 gal. of fuel per year.

The physical properties of the hydraulic fluid in a viscous fan drive may also change over time, and lead to decreased performance and further degradation in cooling performance.

On/Off Fan Drives

An on/off fan drive also responds to changing operating conditions and controls the radiator fan accordingly. However, the on/off drive concept can offer substantially increased performance benefits over a viscous drive. For example, it is either completely off (essentially disengaged) or completely on (engaged at full engine speed), giving it a wider range of efficiency and the ability to maintain engine temperature within a much narrower range ([+ or -]40 [degrees] F compared to [+ or -]48 [degrees] F). The graph at Figure 2 compares the engine temperature range for a typical on/off fan drive with the range for a viscous fan drive under equivalent engine and operating conditions.

Secondly, an on/off fan drive responds to engine sensors that reflect actual engine conditions rather than merely the temperature of air passing through the radiator.

The latest on/off fan drives used in North America are controlled by individual engine sensors, or by input from the diesel engine's electronic control module (ECM), based on intake air temperature, engine coolant temperature and air conditioning pressure. Consequently, the control unit is able to engage the fan clutch only when cooling is required. Fan on time with an on/off fan drive typically amounts to 10 to 15 percent of engine run time for an over-the-road vehicle.

Fan drag and fan blade noise are eliminated during the off cycle, drive belt wear is reduced and radiator abrasion caused by airborne contaminants is lessened, since the fan is not operating as frequently. Since the fan does not require energy in the off mode (very low parasitic drag), fuel savings can be dramatic.




We must remember that they are talking about BIG trucks. but this should also apply to smaller engines and trucks too. It would be nice to have the fan only come on when needed.



I'm not sure you can get these for light duty cars and trucks like most of us drive. I'll bet you could adapt one from a larger truck.....it's not gonna be cheap though!



Sorry for the long post!



Rick

 

I just returned from vacation in Colorado. Temperatures were in the 90's all day long. Running the AC, with the truck unloaded, resulted in the fan locking up and roaring simply driving along a level road at 2400 rpm, 68mph. (I have 4.88 rear axle.) Turn off the AC and open all the windows and it would quiet down.
Pulling the trailer at the same speed would result in basically the same behavior, except on any hill the fan would come on because the motor was working harder.
Here's an example of the power needed to pull some of the hills while loaded with the trailer. When it got to this, I would turn off the cruise control and "drive by EGT" up the hill, limiting it to 1150.

Temperature needle never rose at all, the fan would lock up and roar first.
I'm saying all this because my real world experience found the fan locking up a lot more than 10 - 15%, especially with a load.

 

I also know that in cooler weather the fan will not come on as much.

 

Your truck would probably benifit from an electromagnetic clutch fan. You would show the most benifit from running empty of course since the viscous type clutches don't fully release nor do they fully engage. It's just not as much savings as on a big truck that has a much higher fan load.


MAN that's a LOT of boost! Is that stock? 27-28 psi? It must be chipped! (I don't think my lil ol 6.5L GM does more than about 8-10 psi!!)

 

Again, possibly apples and oranges....Big over the road trucks have MUCH larger radiators and as such don't need the fan running on the flat as much (like they said 10-15% of the time) On a long pull the fan will still cycle.

In an automotive application like your truck the radiator is much smaller than it might be for a medium or heavy duty truck so the fan load is going to be greater. Driving around empty the fan would not probably be needed at all....and going up a hill (empty) it probably doesn't come on at all or once in a while....remembering that it's still turning the fan....viscous clutches don't fully disengage....).

Put a load on the back though and the viscous clutch might be engaged almost continously in warm wx.

When they sized the radiator in your Ford, they had to consider a size that would "look good" as well as work good. Really B I G radiators don't "look good" in a pickup! (so the fan will have to run more often)