mikeyss
Full Access Member
I found pics on ebay. The second picture is the 500w dual setup, looks like one fan is smaller
Keeping coolant and transmission temps under control when towing in the summer heat
- Thread starter Geotrash
- Start date
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20895139, which doesn't match what I purchased from the seller and only comes up in a notation in parts for a 2500 and says the motors and blades must be changed. but doesn't say what wattage it is.
the information out there on it is totally bazaar because the shroud has dual 5 blade fans.
one says: SHROUD KIT,ENG COOLING FAN(7/9 FAN BLADES)(USE T/W MOTOR KITS 15780795 & 15780796 AND BLADE KITS 15780793 & 15780794 IF OEM SHROUD IS STAMPED 20895139)
another part says:
Part Number: 15780789
Shroud. Fan. PACKAGE - ENGINE COOLING.
4.8, 5.3, 6.0 & 6.2 LITER 1/2 TON. 6.2 LITER. 7/9 fan blade. Housing or Panels that surround the cooling fan to direct air. Must replace fan blades and fan motors if OEM shroud is stamped 20895139 or 20895140. W/ELECTRIC COOLING FAN. W/HD cooling.
can't tell by the motor frame either because on rockauto the 500w and 700w motor frame's are indentical looking
can't tell by the fan blades either they look the same in photos, maybe the rear circular plastic around the motor area is thicker or something? but do not have any to compare.
can't tell by the fan blades either they look the same in photos, maybe the rear circular plastic around the motor area is thicker or something? but do not have any to compare.
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gooffeyguy
Tom
Actually the top 3 GM 500w fan motors "exclude" the K5L
ya I missed that part lol and corrected my post
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I wonder how you tell the difference on the fan blades between the 500w and 700w, there is no part number stamped on them
OP
OP
I’ll take a look at the one I have when I get home in a few hours.
is it a 5 blade? 500w or 700w
indeed I just want the best option and it's hard to figure out without ordering and returning stuff, if the dual 5 blade 700w (2nd design) is better then the 7/9 rimmed (1st design) then that's what I want or vica-versa
OP
OP
So I misspoke earlier, my 2012 is actually five blade fans, and that’s what I ordered as well to go with the 700 W fan motor. There are no markings for part numbers on either the fan or the motor.
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mikeyss
Full Access Member
I need to get that fancy cfm reader, since I have both the 5/5 rimless AND I have the 7/9 rimmed in the truck. Both are 700w motors. Any recommendations for a cfm reader?
alpha_omega
Full Access Member
What is your current alternator Kilo code? My 11’ has KW1.
alpha_omega
Full Access Member
Any of the “BT Meters” are good quality for what you’re trying to do. I have one that’s a bit nicer but we use it for when we are jumping. That one is not used for doing stuff like this, which is why I picked up the BT-100.
Is your alternator code the same for those 5 blades?
alpha_omega
Full Access Member
Two hours later I finished this reply. My apologies for the hijack and may the force be with you while reading.
Still on board after the warning? Ok then, buckle up…here we go!
All the research I found shows that the 20903474 Motor is for the 5.3l Yukon’s and not the 6.2l. Are you sure that is the right number for the application? I couldn’t see GM wasting money putting in a 700W motor for no reason, unless it’s the actual physics behind their choice that was then swayed or became convoluted when it came time to make a decision on the 6.2l cooling system (I know, I know…you can bust the docs balls later on “another physics reference” - hey I warned you ahead of time).
What I mean by ”actual physics”: It is quite possible the 5 blade needs the 700w motor because it needs to spin faster in order to run as efficient (more low pressure due to more space between each blade) as the 7/9. By increasing the number of blades you effectively decrease the space between the blades and in turn decrease the amount of low pressure - aka the air that is not being drawn through the cooler/condenser/radiator and pushed by the blades towards your engine. If the fan has a bigger overall diameter, or thicker fan blades, this idea goes out the window, because in this case the impeller used to rotate the fan would need to be larger. Although, this still does not mean that a fan with more blades will have more airflow, only that it will have a higher energy consumption and make less auditory noise.
If the fan was a push style instead of a pull style setup, the fan(s) would run on high nearly full-time. This is because the air being moved by the blades would constantly fight against [not only] the static pressure of the vehicles cooling components, but also the resistant pressure of the incoming headwind while driving; plus while at idle they would be on due to ambient air temps/realfeel temps/atmospheric temps and from the engine, trans, tires, road…etc.
Since our vehicles use a pull style setup the fans usually kick on when the vehicle is at idle, slow moving/stop-and-go traffic, or grade increases (esp while towing). Static pressures are the same, but with the pull style you have to add the closed engine bay and engine into account - plus anything that hinders or impedes the outflow of airflow. Also, outside temps obviously play a role, but let’s get back on track.
So, with an increased number of blades using the same size or a similar diameter fan you will only:
-decrease the sound of the air being moved by decreasing the amount of negative pressure (more blades = less sound / less blades = more sound *think rotor wing aircraft and how much sound a helicopter produces from its blades “chopping” the air - that chop is the negative pressure)
-increase the high pressure air being moved (relative to the static pressures around it).
-increase the energy consumption, but not increase the airflow proportionate to the energy consumption *meaning less efficient (which I believe is not what you guys are aiming for correct?).
You’re not trying to put in a bigger alternator, fan blades and a bigger fan motor in just to move a little more air. Instead, you’re trying to move VOLUME!, which can only happen if their are less fan blades (low pressure), or if they are MUCH thicker (usually) and/or if the fan is much larger in diameter overall.
Even with the latter being the case, you shouldn’t need larger fan motors and alternators because the airflow (cfm) would then be higher than that of a smaller fan running at the same RPM. This does not follow the rules or apply to us because as I mentioned earlier, we have SUV’s with large hot engines that are too close to the fans.
To not let this reply get any longer, check out this paper on the subject. I checked their work, the numbers are right but they are also subjective, and unfortunately their conclusions are not realistic to our circumstances. However, the information is solid and might help fill in any blanks left by my ramblings above.
*I want to go on record and state that I am not responsible for any headaches or further confusion caused by trying to understand the equations in this paper - skip over them, I’ve already ensured they are correct.
https://www.tandfonline.com/doi/pdf/10.1080/19942060.2013.11015454
Still on board after the warning? Ok then, buckle up…here we go!
All the research I found shows that the 20903474 Motor is for the 5.3l Yukon’s and not the 6.2l. Are you sure that is the right number for the application? I couldn’t see GM wasting money putting in a 700W motor for no reason, unless it’s the actual physics behind their choice that was then swayed or became convoluted when it came time to make a decision on the 6.2l cooling system (I know, I know…you can bust the docs balls later on “another physics reference” - hey I warned you ahead of time).
What I mean by ”actual physics”: It is quite possible the 5 blade needs the 700w motor because it needs to spin faster in order to run as efficient (more low pressure due to more space between each blade) as the 7/9. By increasing the number of blades you effectively decrease the space between the blades and in turn decrease the amount of low pressure - aka the air that is not being drawn through the cooler/condenser/radiator and pushed by the blades towards your engine. If the fan has a bigger overall diameter, or thicker fan blades, this idea goes out the window, because in this case the impeller used to rotate the fan would need to be larger. Although, this still does not mean that a fan with more blades will have more airflow, only that it will have a higher energy consumption and make less auditory noise.
If the fan was a push style instead of a pull style setup, the fan(s) would run on high nearly full-time. This is because the air being moved by the blades would constantly fight against [not only] the static pressure of the vehicles cooling components, but also the resistant pressure of the incoming headwind while driving; plus while at idle they would be on due to ambient air temps/realfeel temps/atmospheric temps and from the engine, trans, tires, road…etc.
Since our vehicles use a pull style setup the fans usually kick on when the vehicle is at idle, slow moving/stop-and-go traffic, or grade increases (esp while towing). Static pressures are the same, but with the pull style you have to add the closed engine bay and engine into account - plus anything that hinders or impedes the outflow of airflow. Also, outside temps obviously play a role, but let’s get back on track.
So, with an increased number of blades using the same size or a similar diameter fan you will only:
-decrease the sound of the air being moved by decreasing the amount of negative pressure (more blades = less sound / less blades = more sound *think rotor wing aircraft and how much sound a helicopter produces from its blades “chopping” the air - that chop is the negative pressure)
-increase the high pressure air being moved (relative to the static pressures around it).
-increase the energy consumption, but not increase the airflow proportionate to the energy consumption *meaning less efficient (which I believe is not what you guys are aiming for correct?).
You’re not trying to put in a bigger alternator, fan blades and a bigger fan motor in just to move a little more air. Instead, you’re trying to move VOLUME!, which can only happen if their are less fan blades (low pressure), or if they are MUCH thicker (usually) and/or if the fan is much larger in diameter overall.
Even with the latter being the case, you shouldn’t need larger fan motors and alternators because the airflow (cfm) would then be higher than that of a smaller fan running at the same RPM. This does not follow the rules or apply to us because as I mentioned earlier, we have SUV’s with large hot engines that are too close to the fans.
To not let this reply get any longer, check out this paper on the subject. I checked their work, the numbers are right but they are also subjective, and unfortunately their conclusions are not realistic to our circumstances. However, the information is solid and might help fill in any blanks left by my ramblings above.
*I want to go on record and state that I am not responsible for any headaches or further confusion caused by trying to understand the equations in this paper - skip over them, I’ve already ensured they are correct.
https://www.tandfonline.com/doi/pdf/10.1080/19942060.2013.11015454
alpha_omega
Full Access Member
In relation to my long post, this idea hit me while I was sleeping.
I’m not sure if you guys will have any low pressure issues with your fans or engine temp spikes that are the result of opening the air dam at the lower grille. This could prevent the fans from working at their peak performance regardless of their size and how big of a motor/alternator combo that you use. Just a thought. I don’t want to see you trade trans temps for engine temps, and thinking that you moved the aux trans cooler to help prevent static pressure but result in an increased low pressure as a result.
I’m not sure if you guys will have any low pressure issues with your fans or engine temp spikes that are the result of opening the air dam at the lower grille. This could prevent the fans from working at their peak performance regardless of their size and how big of a motor/alternator combo that you use. Just a thought. I don’t want to see you trade trans temps for engine temps, and thinking that you moved the aux trans cooler to help prevent static pressure but result in an increased low pressure as a result.
RooTBeeRthe1st
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alpha_omega
Full Access Member
I have to laugh whenever I see the words “HD Aux Trans Cooler” in regards to a vehicle with the payload ours have/had.
Is yours a PPV? I don’t own one so I’m not sure what they have other than the Z71 and/or Z95. Mine is the Z55. Is their fan setup any different?
OP
OP
A fair concern, for sure. However, the area above and below the bumper are isolated from each other by the thick plastic splash shield that runs from just below the radiator to the frame crossmember beneath the harmonic balancer.
OP
OP
Made it through! One thing that comes to mind is that I have no way to know that my 2012 doesn’t already have 700w fan motors even though it doesn’t list the K5L cooling package. It does have 5 bladed fans and it has the heavy duty towing package, as evidenced by the factory trailer brake controller, engine and transmission oil coolers and the power steering fluid cooler.
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