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Electric Fan clutch

Im all for the electric control, simplicity of adjustment to engauge sooner, longer, or on demand is great. But the question of what percentage rpm loss at it's highest lockup rate is the big concearn to me.

As soon as 100% lockup is achievable on one, that will afford the best results imo. Semi trucks chased and walked away from percentage lockup long ago. Every now and then one of them will try reinventing one, but no draw of power until needed, then full cooling capacity continues to prove the best for cooling and mpg.
 
The percentage of loss in RPM's would be the same as a thermal fan clutch. They work on the same priciples, one just uses a bimetal spring, and one uses an electrically heated coil with a rpm sensor to tell the controller how much it is applying. Borg warner makes a controller and sells a fan clutch to fit many heavy trucks that uses the visctronic design.
 
Yeah, but different fanclutches have different rate of lockup to rpm ratio, and have different total percentage of lockup. If they make an electric fanclutch with 100% lockup we could run, it would be magic.

Thats the only reason I didnt jump onto the ford one ak diesel driver found and is using and waiting for Leroy's testing to be completed on the actual clutch system.

When overheating down the hiway and getting hot, the idea of downshift for more rpm helps drive up fan speed to pull more air(and more coolant flow). While it is a bit of a problem for gmt400 trucks, hummer/hmmwv airflow on freeway is WAY worse. Loosing 500 or more rpm on the fan is huge.

I havent mentioned it much because it doesnt apply to this forum much at all, but in the fleets I wrenched on and ran, many class 7&8 trucks were there, as well as heavy equipment. My ase master certs were auto, med& heavy duty rigs, truck equipment. So yeah, quite familiar with slip style fan clutches in rigs. I still have multiple master keys for Pete's, KW, frieghtliner, Sterling, etc. Life long friend is head of a republic services fleet, and keeps me aprised of many of the headaches as they arise just in general conversation.

They are a neat concept for some areas of the country, with rigs that have a properly oversized radiator that does not need the fan engauged much down the hiway. When the radiator btu/h is sized too close to engine btu/h output like gmt400 and hummers- not as good. After loosing many engines from overheating in big rigs, many fleets in the southwest, including republic services, has had to retro fit air fan clutches with 100% lockup in place of the slip style clutches.

The other huge factor for heat transferance is humidity. Having been born in Tallahassee, and visiting there and many areas over the years, I know a touch about humidity, besides what we learned in science class. Humid air on the radiator increases it's thermal convection at an amazing level. Think how good does an air cooled engine shed heat vs water cooled. Radiator is no different. Dry air is an insulator.

When an OTR rig goes through dry& hot southwest, the drivers has to back down and take it easier to not overheat. They hit areas with more humidity at the same temps and it's hammer down. Wont overheat near as easy because raditor starts working twice as well.

Gmt400 inital hot climate testing was not done in the current dry climate area they use. That is simply why they goofed up. Ford 6.9 & 7.3 did their testing in dry Arizona and quickly beefed the radiator for the trucks vs the gas engines. GM stuck their head in the sandand was expecting to dump the program almost yearly.

AM General-hmmwv were never designed to drive beyond 55 mph. The airflow from aerodynamics of the verticle windshield and angled radiator kills it. Until your above 85% throttle for long hiway hills there isn't much of a problem in hmmwvs overheating. Once head wind or foreward speed combines to 70 mph, over half the incoming airflow is lost. Hence the hood scoop I helped design down in the Cali NASA wind tunnel that was turned over to the USMC. My dads envolvement in gubmint fly fly world got me into contact with a couple NASA engineers, and a good friend in charge of a USMC base wheeled vehicles fleet. So it all worked out good, but the best improvment of getting a bigger, more efficient, verticle radiator was the final answer, along with a 100% lockup fan clutch system.
 
The ev or thermal type is never going to be much more than 90% lockup, thats just the nature of a viscous drive. No visctronic can achieve 100% as theres no real lockup clutch in them, jusy badically a torque converter that uses a 10k weight silicone fluid medium. I know it's been talked about with some of the serviceable fan clutches to change the silicone out in them with 20k or even 30k weight silicone, but supposedly this makes the morning sickness quite severe. The only ways to achieve 100% lockup will be to go to some type of clutched fan drive(wether it be electric, air, or hydraulic), otherwise 85-90% lockup is about the best you're going to be able to achieve.
 
That's what I was afraid of hearing. I know they were working on an electric that was supposed to use twin system fluid for up to 60-70%. Then a system that pushed a driven gear into the fixed groove gear for solid lockup. The problem was timing the engaugement to not wear the gear tips too quickly. It had to use an inducer pick up to time it. It's been a while since I heard anything about it- just hoping...
Of course if they get it done it would cost around $1000 so, yeah...
 
Will L. said:
The other huge factor for heat transferance is humidity. . .

When an OTR rig goes through dry& hot southwest, the drivers has to back down and take it easier to not overheat. They hit areas with more humidity at the same temps and it's hammer down. Wont overheat near as easy because raditor starts working twice as well.
Click to expand...

As an aside, agree that heat exchange of humid air is definitely a factor in cooling the motor. Will argue that humid air also has a secondary factor of lower parasitic drag which in turn reduces the amount of heat that the radiator needs to shed. So humidity has a double effect on the system as a whole. :)
 
JayTheCPA said:
As an aside, agree that heat exchange of humid air is definitely a factor in cooling the motor. Will argue that humid air also has a secondary factor of lower parasitic drag which in turn reduces the amount of heat that the radiator needs to shed. So humidity has a double effect on the system as a whole. :)
Click to expand...

Explain the parasitic drag reduction please.
 
@Will L. ... what if anything do you see wrong with a hummer type hyd lock up also using all the hummer fan blade & stuff ??

I haven't installed my new set up that Unique built but I have seen a video and it sucks as hard as my semi did... looking forward to giving it a try myself..
 
Will L. said:
Explain the parasitic drag reduction please.
Click to expand...

The more humid the air, the lower the density. Naturally this presumes that the water is still in a gas / vapor state and not condensing. The sailing community recognizes this where humid days bring less 'punch' in the sails. The aviation community sees this where more humidity gets less lift from the wings. While aircraft get lower climb performance from higher humidity, they get better cruise performance (distance). Baseball also recognizes this with an out-of-the-park hit more likely in higher humidity conditions.

Effect on a vehicle is that humidity reduces drag as it passes through the air (parasitic drag). So for the same speed (and all other factors remaining equal), the vehicle in the higher humidity environment needs to overcome less drag than the one in lower humidity.
 
ak diesel driver said:
My biggest issue with most of those setups is cost. I only have a couple hundred in mine
Click to expand...
And I don't think the van clutch if you can find a used one will cost anymore. New van clutches that will screw right onto the thread on water pump are under $200 on ebay, and a brand new fan blade was what, $40 on RA. So if you can find a used fan and clutch for $150, then you will have a diesel fan designed for the lower RPM's that will thread right on, and appears to use the correct diameter fan blade. Haven't been able to find a pinout, so next time I'm by the dealership, I'll see if they will let me get a copy of the pinout that way.
 
Excellent! :)


Last piece of the puzzle is the controller. Reviews of Hayden's offerings are all over the place in terms of reliability . . .
 
I would try it myself , but I cannot till I get out from under a pc of real-estate. Then a new Hydro-boost. .... lol
 
Except they are trying the lml clutch which uses a 25" diameter fan. And from my research,vit's not an electro magnet, but instead a fast responding heating element. 7nfortunately one won't work for me, so I'm mot gonna fork out the money for one when I know I don't have the clearance for it. I was hoping Leroy would have his done by now so I could see if that one would work for me. I just don't have much room in mine. Still need to get out and put my kennedy/hayden unit in.
 
sctrailrider said:
@Will L. ... what if anything do you see wrong with a hummer type hyd lock up also using all the hummer fan blade & stuff ??


I haven't installed my new set up that Unique built but I have seen a video and it sucks as hard as my semi did... looking forward to giving it a try myself..
Click to expand...

Sorry i missed this earlier.
Price to play with. If i had my hands on one I would
mess wih it. Using the power steering pump for the luid and pressure to operate, then the control system is a bit elaborate. Iirc it is a default on system, and the pressure releases it to spin free. I have no knowledge on the fan itself.
 
Burning oil said:
Mine is done! just waiting on some prototype results to come back. I have all the parts ready to go.
Click to expand...
Wished I would have known before I bought a Kennedy. Been waiting and couldnt wait any longer after getting WARM on vacation. If yours pans out, the thread on one may have some duramax customers as I know at least one looking for one right now.
 
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