Simp5782
SNOW TACKLER!
maybe some people like the sound that the truck makes when the fan clutch kicks in, sounds something along the lines of a 747 at full throttle on take off 
Since we are on the subject of electric fans...
- Thread starter freebird01
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oldmisterbill
Grumpy Old Man
For arguments sake. What if ("air gets hotter when the fan slows because it has more time to absorb the heat") we think outside the box "saturation of the air with heat". The more air we move the cooler the air - maybe? because the air doesn't absorb all the heat as in a ratio effect of heat to air volume (kinda like a saturation point). I hope I am making sense. more air would require the air not to be as hot as in "less air". I know when we upgraded the HVAC system at the plant years ago they added bigger fans that mover more air faster. On the other hand we had a tube in tube heat exchanger (liquid -to - liquid) I think (if I remember correctly0one of the engeneers said if the water was traveling too fast there would be cavatation of sorts betwen the rushing water and the cold side slowing down the exchange. I may have that wrong -that is why I am throwing this out to debate.
Have at it guys !! - I think there is some one here with HVAC experience.
Have at it guys !! - I think there is some one here with HVAC experience.
82F100SWB
Full Access Member
The water moving too fast theory holds true. Try running an engine with no thermostat at all, and no restriction, it will overheat if run hard(mud/trail trucks are my experience.) I am a HVAC guy, and the lack of heat exchange due to water moving too fast is an issue with boiler systems.
I have no problems keeping my 460 cool with a pair of fans off of a 3.1L Chevy malibu, but, I wouldn't put e-fans on my IDI.
I'm not sure what rpm rating that cfm is at for the stock fan, I know the stocker on my 460 was rated at 10,000 also. I got these figures from a Ford manual quite a while back, and they stuck in my head.
I think my issues with my 6.9 were largely related to operating far beyond what the cooling system was designed for, both in GCWR and power levels, the engine would overheat before EGT's got out of control, but, I could maintain 14 psi with only 900 degrees on the pyro, mind you that's in the non gated banks location, probe right before the turbo, after the y-pipe. IDI's by design put alot of heat into the cylinder heads with the precups, and I was definitely operating mine far beyond design and what most people consider safe. I still have no sweet clue where my timing is actually at on that engine, that will affect cylinder temps without affecting pyro readings, plenty late model Cummins guys have learned that the hard way.
I would have loved to have ran my 6.9 on a dyno, it would run nearly dead even with my Cummins when it was only making 25 psi, and that's somewhere around the 225-230/550-575 mark at the wheels, and the trucks are similar in weight.
No changes to my 6.9 other than the lack of a turbo, even the same fuelling, and you can run it as hard as you want, and it will not overheat.
I have no problems keeping my 460 cool with a pair of fans off of a 3.1L Chevy malibu, but, I wouldn't put e-fans on my IDI.
I'm not sure what rpm rating that cfm is at for the stock fan, I know the stocker on my 460 was rated at 10,000 also. I got these figures from a Ford manual quite a while back, and they stuck in my head.
I think my issues with my 6.9 were largely related to operating far beyond what the cooling system was designed for, both in GCWR and power levels, the engine would overheat before EGT's got out of control, but, I could maintain 14 psi with only 900 degrees on the pyro, mind you that's in the non gated banks location, probe right before the turbo, after the y-pipe. IDI's by design put alot of heat into the cylinder heads with the precups, and I was definitely operating mine far beyond design and what most people consider safe. I still have no sweet clue where my timing is actually at on that engine, that will affect cylinder temps without affecting pyro readings, plenty late model Cummins guys have learned that the hard way.
I would have loved to have ran my 6.9 on a dyno, it would run nearly dead even with my Cummins when it was only making 25 psi, and that's somewhere around the 225-230/550-575 mark at the wheels, and the trucks are similar in weight.
No changes to my 6.9 other than the lack of a turbo, even the same fuelling, and you can run it as hard as you want, and it will not overheat.
timothyr1014
Full Access Member
although I have not yet gone to e-fans, I would tend to agree with mel on this one. In an automotive engineering class I took years ago one of the concepts was about properly designed cooling systems. The instructor made an interesting point that for every square foot of direct frontal opening you will effectivly get 3520 CFM at 40 mph...I believe the factory radiator core is roughly 24"x31"
Now for the side of a factory fan being able to pull 14kcfm (which I will assume is rated at 15~1800 RPM) I would believe; because watch this.....
with a radiator surface area of 4 sq/ft moving at 40MPH would equal 14080 CFM of air flowing through the radiator....and the other side of this argument is that at anything above 40MPH you have negated the effect of the fan...
however consider this.....with a radiator core with a 25% blockage, the usage surface area of the radiator becomes 3sq/ft, and although the same 14080cf of air are flowing accross it, wil only be able to use 10560cf of that air for cooling.
Now to my point.....IF you can keep the truck moving at 40MPH it will not matter which fan you have as there will be more air being pushed through the radiator than the fan can pull....
Now for the side of a factory fan being able to pull 14kcfm (which I will assume is rated at 15~1800 RPM) I would believe; because watch this.....
with a radiator surface area of 4 sq/ft moving at 40MPH would equal 14080 CFM of air flowing through the radiator....and the other side of this argument is that at anything above 40MPH you have negated the effect of the fan...
however consider this.....with a radiator core with a 25% blockage, the usage surface area of the radiator becomes 3sq/ft, and although the same 14080cf of air are flowing accross it, wil only be able to use 10560cf of that air for cooling.
Now to my point.....IF you can keep the truck moving at 40MPH it will not matter which fan you have as there will be more air being pushed through the radiator than the fan can pull....
oldmisterbill
Grumpy Old Man
Thats the kind of information I was seeking. Now throw this into the soup. I used to pull hills loaded over 40 MPH.the temp would rise till the fan clutch locked then the engine would cool and the fan clutch would unlock.This happened cycle after cycle when pulling hard. Remember over 40 mph is the key. And how much restriction do we have int he engine compartment & grill. I mentioned a while back ,that when I got my truck it had been a hotshot truck B4.The previous owner had shimmed the hood leaving a 1/2 in or so gap at the rear of the hood.I had good luck cooling with a stock fan & radiator. I commonly grossed 20,000 to 26,000 lbs.
By the way I'm not trying to prove some one wrong or right just seeking more knoledge & understanding. A good debate can do this sometimes. So lets keep the comments going!!
By the way I'm not trying to prove some one wrong or right just seeking more knoledge & understanding. A good debate can do this sometimes. So lets keep the comments going!!
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I also read another theory on the "no thermostat " overheating problem which I find plausible. Their theory was the waterpump develops a "head pressure" on it's output. This pressure develops at a restriction point on the output of the pump. This point happens to be the thermostat. If you take the thermostat out, the next restriction point is the top tank of the radiator, where the water is forced through the small passageways of the core. Putting the pressure head of the pump in the top radiator tank overwhelms the radiator cap, and makes it puke out coolant, and you think the engine is overheating.
They said if you want to run a engine without a thermostat, then take the thermostat out, cut the guts out of it, and re-install it. It will be a like a thin washer with a hole in the middle, and this keep the pressure of the waterpump off the radiator cap.
Ever compare the pulley sizes of a old 60's non emission engine to a later model 70-80's emissions engine with lots of accessories? You will find the early engines had nearly a 1 to 1 ratio from the crank pulley to the waterpump, while the later model 70's and 80's engines have a waterpump pulley that is smaller than the crank pulley to increase the coolant flow through the system for better cooling and also increased the fan speed.
They said if you want to run a engine without a thermostat, then take the thermostat out, cut the guts out of it, and re-install it. It will be a like a thin washer with a hole in the middle, and this keep the pressure of the waterpump off the radiator cap.
Ever compare the pulley sizes of a old 60's non emission engine to a later model 70-80's emissions engine with lots of accessories? You will find the early engines had nearly a 1 to 1 ratio from the crank pulley to the waterpump, while the later model 70's and 80's engines have a waterpump pulley that is smaller than the crank pulley to increase the coolant flow through the system for better cooling and also increased the fan speed.
timothyr1014
Full Access Member
I have no issue with civilized debates....thats how progress happens
As you mentioned, 40MPH is a key, but the other, just as critical is the usable surface area of the radiator....lets say for example some of your radiator fins are beat up or full of crap (somehow totally blocked)...taking that same equation I used above, if 25% of the radiator is blocked (outside, not coolant passages) your usable air-flow for thermal transfer would be the 10560cfm....however with the fan clutch locked this would increase to 14000cfm
keep in mind the numbers are a little misleading....14080cfm at 40mph does not account for any air turbulance or redirection from a brush bar, off road lights, ac condenser, core bracing etc. The usable cfm getting back to the radiator could actually be down closer to 11000 cfm which would require more speed (or a fan) to compensate. A factory shrouded fan will attempt to bull the extra air through (speed adds pressure, fan adds suction)
At the end of the day you have to look at the cooling system as a whole...thermal BTU output of the motor under full load (and then you start the debate of what is full load), thermal transfer rate of the coolant (capacity and flow rate), and thermal transfer rate of the radiator (how big and how much air is needed). The only reason I am further complicating the issue is because it raises the question of what were the conditions the original cooling system was expected to work under...IIRC my 86 CC Dually has a factory GCWR of ~14k.
Granted she is non-turbo but between my rodney red, evans coolant, and additional frame oil cooler I have many times grossed 18~20k pulling 8% grades with the hammer down while its 107*, and I am seeing 215* on the gauge with no fan lock....thats moving at ~40mph, with my big **** push bar and off-road lights sitting there blocking air-flow.
My agreement with Mel is to say "how up to your intended task is your cooling system",
As you mentioned, 40MPH is a key, but the other, just as critical is the usable surface area of the radiator....lets say for example some of your radiator fins are beat up or full of crap (somehow totally blocked)...taking that same equation I used above, if 25% of the radiator is blocked (outside, not coolant passages) your usable air-flow for thermal transfer would be the 10560cfm....however with the fan clutch locked this would increase to 14000cfm
keep in mind the numbers are a little misleading....14080cfm at 40mph does not account for any air turbulance or redirection from a brush bar, off road lights, ac condenser, core bracing etc. The usable cfm getting back to the radiator could actually be down closer to 11000 cfm which would require more speed (or a fan) to compensate. A factory shrouded fan will attempt to bull the extra air through (speed adds pressure, fan adds suction)
At the end of the day you have to look at the cooling system as a whole...thermal BTU output of the motor under full load (and then you start the debate of what is full load), thermal transfer rate of the coolant (capacity and flow rate), and thermal transfer rate of the radiator (how big and how much air is needed). The only reason I am further complicating the issue is because it raises the question of what were the conditions the original cooling system was expected to work under...IIRC my 86 CC Dually has a factory GCWR of ~14k.
Granted she is non-turbo but between my rodney red, evans coolant, and additional frame oil cooler I have many times grossed 18~20k pulling 8% grades with the hammer down while its 107*, and I am seeing 215* on the gauge with no fan lock....thats moving at ~40mph, with my big **** push bar and off-road lights sitting there blocking air-flow.
My agreement with Mel is to say "how up to your intended task is your cooling system",
6.9poweredscout
Bleeds IH red...
I want to run electric fans in the scout but I'm not sure if they will keep it cool enough in the woods. I can drive on the street with NO fan at all. I did for a week before I had the hub machined for a flex fan. I like the simplicity of the flex fan, engines running, fan is working, but everytime I hit water the fan bends and puts a new hole in the rad.
I don't tow with it....much, maybe to move a car across town with the trailer, so I don't think id have a big issue there. The only thing is my rad is only about 22 x 20 or so with about 1-3/4 to 2" between the rad and fan snout. I was thinking like dual 11 inch fans, one high, one low on the rad. The only ones I find are like 1500 CFM each though, so I don't know if 3000 CFM is enough. My cooling system is tip top (cleaned oil cooler REALLLYYY good) and new rodney red alum. radiator. What's your suggestions guys?
-Jon
I don't tow with it....much, maybe to move a car across town with the trailer, so I don't think id have a big issue there. The only thing is my rad is only about 22 x 20 or so with about 1-3/4 to 2" between the rad and fan snout. I was thinking like dual 11 inch fans, one high, one low on the rad. The only ones I find are like 1500 CFM each though, so I don't know if 3000 CFM is enough. My cooling system is tip top (cleaned oil cooler REALLLYYY good) and new rodney red alum. radiator. What's your suggestions guys?-Jon
I would speculate that the figures given are under ideal conditions. That would be a radiator, moving through the air with nothing behind it or in front of it. Undoubtedly there is presure in the engine compartment and blockage on the front side that prevents this ideal from being reached. No doubt the fan is needed to overcome this fact. Possibly also the faster the truck goes, there is a potential to have less air flow as the engine compartment presure increases and turbulance from the grill, bumper, etc increases and may create partial vacuums. 
oldmisterbill
Grumpy Old Man
Guess I sahould edit better -with my big finners I need to. I wrote 12 in gap between the hood & cowl. I ment 1/2 in gap. My bad.
timothyr1014
Full Access Member
Mel - you are exactly correct, there are many factors that contribute to total flow (and it backing-upinside the engine compartment), I was just trying to point out that although 14000cfm sounds like this huge amount, it is actually attainable at a normal road speed....Just as
-Jon...In my experience I am not big on electric fans for off-road rigs....while I have seen them work, and they have some definate advantages, one of the issues you could run into is lack of overall air flow for the conditions. Consider this - while you may get enough flow to cool while pulling a trailer, you are also gaining forward speed which provides additional air...when running hard in 4lo you are gonna be demanding power with very little forward motion to supliment the fan flow. As I said, I have seen it work, and one of the tricks is to make sure that you have enough gear so that you are not having to hammer to badly.
-Jon...In my experience I am not big on electric fans for off-road rigs....while I have seen them work, and they have some definate advantages, one of the issues you could run into is lack of overall air flow for the conditions. Consider this - while you may get enough flow to cool while pulling a trailer, you are also gaining forward speed which provides additional air...when running hard in 4lo you are gonna be demanding power with very little forward motion to supliment the fan flow. As I said, I have seen it work, and one of the tricks is to make sure that you have enough gear so that you are not having to hammer to badly.
6.9poweredscout
Bleeds IH red...
exactly my thoughts, i know the fixed flex fan can do it, i'm just not sure with the e-fans. the nice thing with the e-fans is they can be turned off in deep water. the flex fan blades are too soft, and i'm afraid the HEAVY (like 1/8 thick steel) factory scout fan will fatigue the alum adapter i had made.
-Jon
-Jon
MIDNIGHT RIDER
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As per oldmisterbill, my truck was also previously owned by a hot-shotter; it even had a genuine big-truck 5th-wheel.
An interesting piece of history is that the previous owner was also a one-legged guy and the truck was factory-original 4-speed manual; he had a bracket welded onto the clutch-pedal with an old gear-shifter pole welded onto that bracket and worked the clutch by hand --- believe it or not.
The truck was a year or so old when I got it.
I wish I had of known about the shimming the rear of the hood trick many years ago; that would have to really open up under-the-hood air-flow and dramatically bring down under-hood temperatures.
I think I will experiment with a cable-operated or cylinder-operated device that would raise the rear of the hood on demand.
As per MEL's note on the diesel-electric locomotives, in most cases, those radiators are flat-ways in the roof, with little, if any, air-flow due to movement.
The only air that gets through those radiators is via those huge electric fans.
This thread has became very interesting and informative without becoming an argument.
Carry on.
An interesting piece of history is that the previous owner was also a one-legged guy and the truck was factory-original 4-speed manual; he had a bracket welded onto the clutch-pedal with an old gear-shifter pole welded onto that bracket and worked the clutch by hand --- believe it or not.
The truck was a year or so old when I got it.
I wish I had of known about the shimming the rear of the hood trick many years ago; that would have to really open up under-the-hood air-flow and dramatically bring down under-hood temperatures.
I think I will experiment with a cable-operated or cylinder-operated device that would raise the rear of the hood on demand.
As per MEL's note on the diesel-electric locomotives, in most cases, those radiators are flat-ways in the roof, with little, if any, air-flow due to movement.
The only air that gets through those radiators is via those huge electric fans.
This thread has became very interesting and informative without becoming an argument.
Carry on.
Simp5782
SNOW TACKLER!
On another note. My Fans are working great. I also had the idea for the older trucks instead of increasing your alternator, perhaps you could invest in a capacitor. Like what they use for stereo systems. They have a 24volt surge and often have 4 positive and negative poles. Would help running the fans to it to help for when they kick off and on during driving conditions.
Well, I thought I would bring this old thread back for a update. I believe it was in one of the other fan/cooling threads I mentioned I converted to two 16" electric fans. These were not Taurus or any other factory fan, they were new off the shelf 16" fans from the local Advance store, #226116, 1,400 cfm each. I used both side by side.
I can now tell you for sure, they are not enough to cool the truck. But it took all summer to figure it out. Hauling loads around town is no problem, no matter what the size load, A/C on too. When I got into trouble was going camping, fully loaded, at interstate speeds going up some long hills. This is where you have it floored for long periods of time, doing 45mph or less in 4th gear or less. It gets hotter and hotter.
I also have verification on the factory gauge system. I left the stock gauge in place, but added a mech temp gauge in the driver's side head, eliminating the overtemp switch. I remember when it was all stock, my temp gauge would go up to about the "A" in "NORMAL", and then would peg over to hot and the engine light would come on. Watching it the other day with the mech gauge, when the factory gauge reaches the "A", the new mech gauge is reading approx 240F. When the mech gauge started approaching 250f, I pulled over and let it cool off for about 15 min.
Some other things I have learned that you may already know, but I can confirm;
-You will need a bigger alternator if you run fans larger than these. These fans were rated at approx 20 amps each. So this took 40 amps from the stock alternator. I never had a problem with this, but I could tell it was at the limit when the fans were on, the A/C was on with the blower on high, and the headlights were on. If you run the required higher cfm fans, they are definitely going to pull more amps(can't get something for nothing right?) and the stock alt is definitely not going to handle the load properly.
-Remember to tie the A/C system into the new electric fan setup. I didn't, and had the high pressure relief valve pop-off on me on the A/C compressor. This means you need to run relays to power the fans. You also need to install a blocker diode in this A/C tie in, or when the thermostat kicks on to run the fans it will kick on the A/C compressor.
What I did today was re-install the factory clutch fan and shroud, and used some small angle iron cut, drilled, and welded to bolt the fan blades to the waterpump pulley. This locked the fan together, and after a test drive, I didn't hear or see anything I didn't like. I could only hear the fan roar a little bit if I got over 2000 rpm. With the overdrive now, I rarely go over 2000 rpm, and I am thinking if I am pulling hard in a lower gear, I should be at or over 2000 rpm and that fan roar hopefully will be a good thing. I will have to wait and see how this works, but I hope it does, since this is the last resort for my heavy hauling/cooling problem.
I can now tell you for sure, they are not enough to cool the truck. But it took all summer to figure it out. Hauling loads around town is no problem, no matter what the size load, A/C on too. When I got into trouble was going camping, fully loaded, at interstate speeds going up some long hills. This is where you have it floored for long periods of time, doing 45mph or less in 4th gear or less. It gets hotter and hotter.
I also have verification on the factory gauge system. I left the stock gauge in place, but added a mech temp gauge in the driver's side head, eliminating the overtemp switch. I remember when it was all stock, my temp gauge would go up to about the "A" in "NORMAL", and then would peg over to hot and the engine light would come on. Watching it the other day with the mech gauge, when the factory gauge reaches the "A", the new mech gauge is reading approx 240F. When the mech gauge started approaching 250f, I pulled over and let it cool off for about 15 min.
Some other things I have learned that you may already know, but I can confirm;
-You will need a bigger alternator if you run fans larger than these. These fans were rated at approx 20 amps each. So this took 40 amps from the stock alternator. I never had a problem with this, but I could tell it was at the limit when the fans were on, the A/C was on with the blower on high, and the headlights were on. If you run the required higher cfm fans, they are definitely going to pull more amps(can't get something for nothing right?) and the stock alt is definitely not going to handle the load properly.
-Remember to tie the A/C system into the new electric fan setup. I didn't, and had the high pressure relief valve pop-off on me on the A/C compressor. This means you need to run relays to power the fans. You also need to install a blocker diode in this A/C tie in, or when the thermostat kicks on to run the fans it will kick on the A/C compressor.
What I did today was re-install the factory clutch fan and shroud, and used some small angle iron cut, drilled, and welded to bolt the fan blades to the waterpump pulley. This locked the fan together, and after a test drive, I didn't hear or see anything I didn't like. I could only hear the fan roar a little bit if I got over 2000 rpm. With the overdrive now, I rarely go over 2000 rpm, and I am thinking if I am pulling hard in a lower gear, I should be at or over 2000 rpm and that fan roar hopefully will be a good thing. I will have to wait and see how this works, but I hope it does, since this is the last resort for my heavy hauling/cooling problem.
