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Cooling fan shootout - this should cause some discussion (disagreement)


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#1 _74LH_

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Posted 03 May 2017 - 09:20 AM

Watch below and discuss...this is a great online show by the way.

https://youtu.be/ZXdLgaFXZzs

Hopefully this puts some misconceptions to bed, or causes some arguments haha

#2 Bigfella237

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Posted 03 May 2017 - 10:43 AM

Sorry to say Daniel but you're a day late and a dollar short...

 

http://www.gmh-toran...ns/#entry994759

 

...I posted it yesterday! ;)



#3 _74LH_

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Posted 03 May 2017 - 03:57 PM

Ah yes but I have a comment! (albiet yours haha)

Technically I'm a month in front though as I'm a subscriber to motor trend on demand so I saw this a month before it hit YouTube!

And I'm any case I run thermos so this just reaffirmed my decision haha

#4 _Muzzy_

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Posted 03 May 2017 - 04:12 PM

I did the dyno tests and it was 6 RWHP saving on std 4 blade fan on Holden 6 , I run thermos !

#5 RallyRed

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Posted 03 May 2017 - 05:07 PM

I guess what's missing in the comparo is the actual cooling efficiency of the fans . for example....if one fan takes 4 more HP, but delivers 150% cooling compared to the other,then it may be worth it?



#6 _74LH_

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Posted 03 May 2017 - 05:59 PM

I guess what's missing in the comparo is the actual cooling efficiency of the fans . for example....if one fan takes 4 more HP, but delivers 150% cooling compared to the other,then it may be worth it?


That's a good point. Although I would counter that cooling capacity could easily be accounted for with modern coolants and bigger and better flowing radiators.
I invested in a 3 core aluminium radiator and I think the fans only come on when it's either a super hot day or my right foot has been heavier than normal.

Another thing I just thought up (in my not at all engineering or engine building mind) is that without that extra drag on the engine the engine would be running under easier conditions and hence wouldn't get as hot or have parasitic loss

#7 RallyRed

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Posted 03 May 2017 - 06:15 PM

The other thing my old head popped up was this one.....

 

You get nothing for nothing.

If a mech. cooling fan robs say 10hp.....then to get a thermo elect one to do the same work....will need an alternator  to supply an electric motor, and that alternator will that take 10hp?? wont it.?

 

Unless the electrical deal is substantially more efficient.



#8 Peter UC

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Posted 03 May 2017 - 07:20 PM

Well we can calculate this, a cooling fan will draw about 30A, so at 12V the power consumption is around 360W or 0.36kW or 0.48hp and there will be losses through the charging system etc so lets call it 1hp

 

You're forgetting one important fact, the mechanical fan may only use say 1hp at idle, i.e. when you need the cooling, but as the engine speed increases so does the power consumption.

 

An electric fan works independantly from engine speed, so when the engine is at idle or low speed the electric fan will spin at the maximum rpm and gives you the necessary cooling unlike a mechanical fan,

 

Also don't forget an electric fan is only on when you need it not all the time.



#9 RallyRed

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Posted 03 May 2017 - 09:12 PM

Well we can calculate this, a cooling fan will draw about 30A, so at 12V the power consumption is around 360W or 0.36kW or 0.48hp and there will be losses through the charging system etc so lets call it 1hp

 

You're forgetting one important fact, the mechanical fan may only use say 1hp at idle, i.e. when you need the cooling, but as the engine speed increases so does the power consumption.

 

An electric fan works independantly from engine speed, so when the engine is at idle or low speed the electric fan will spin at the maximum rpm and gives you the necessary cooling unlike a mechanical fan,

 

Also don't forget an electric fan is only on when you need it not all the time.

simples....you are correct..



#10 LJ RB30

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Posted 03 May 2017 - 09:36 PM

Ummm seeing (as he said ) its a thermal clutch fan!

And the radiator DOESNT have coolant in it so its cold!

And as he said "Its cool in here"

Obviously the clutch in the fan isnt goin to load up as it would in a vehicle with a hot radiator in front!


Id go thermo fan anyway

Edited by LJ RB30, 03 May 2017 - 09:38 PM.


#11 _LS1 Taxi_

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Posted 03 May 2017 - 10:28 PM

Well we can calculate this, a cooling fan will draw about 30A, so at 12V the power consumption is around 360W or 0.36kW or 0.48hp and there will be losses through the charging system etc so lets call it 1hp
 
You're forgetting one important fact, the mechanical fan may only use say 1hp at idle, i.e. when you need the cooling, but as the engine speed increases so does the power consumption.
 
An electric fan works independantly from engine speed, so when the engine is at idle or low speed the electric fan will spin at the maximum rpm and gives you the necessary cooling unlike a mechanical fan,
 
Also don't forget an electric fan is only on when you need it not all the time.


Smarty pants!

#12 _74LH_

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Posted 04 May 2017 - 08:01 AM

Well we can calculate this, a cooling fan will draw about 30A, so at 12V the power consumption is around 360W or 0.36kW or 0.48hp and there will be losses through the charging system etc so lets call it 1hp

You're forgetting one important fact, the mechanical fan may only use say 1hp at idle, i.e. when you need the cooling, but as the engine speed increases so does the power consumption.

An electric fan works independantly from engine speed, so when the engine is at idle or low speed the electric fan will spin at the maximum rpm and gives you the necessary cooling unlike a mechanical fan,

Also don't forget an electric fan is only on when you need it not all the time.


Wow, someone did the math! Awesome! Great answer.

Quick one on the energy draw though, it wouldn't necessarily have any additional draw on the engine itself would it? As the fans run off the battery, which is constantly replenished by the alternator. So as long as the battery and alternator are up to the load requirements of the circuit you could add fans, head units, amps, radios etc and it wouldn't have any more affect on the engine, unless you upgraded the alternator, which I've never heard of anyone running fans needing to do

#13 StephenSLR

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Posted 04 May 2017 - 08:34 AM

without that extra drag on the engine the engine would be running under easier conditions and hence wouldn't get as hot or have parasitic loss

 

You save in fuel consumption too.

 

s



#14 _74LH_

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Posted 04 May 2017 - 12:55 PM

You save in fuel consumption too.

s


Oh absolutely, could make the same argument for electric water pumps, fuel pumps, oil pumps etc. It all has to add up to making the engines life easier.
Although I've always been of the opinion that electric everything (such as water, fuel etc) just leaves more things that can go wrong

#15 StephenSLR

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Posted 04 May 2017 - 02:13 PM

electric water pumps

 

I read a Street Machine article on these back in the 80's. At the time they were so expensive and saved very little horsepower that the pump wouldn't pay itself off. Of course with changes in technology making things cheaper, high fuel prices and that they probably didn't expect me to still own the same car; things may be different.

 

s



#16 _74LH_

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Posted 04 May 2017 - 03:26 PM

I read a Street Machine article on these back in the 80's. At the time they were so expensive and saved very little horsepower that the pump wouldn't pay itself off. Of course with changes in technology making things cheaper, high fuel prices and that they probably didn't expect me to still own the same car; things may be different.

s


Oh of course, with the advancement of tech since the 80s there's bound to be more reliable stuff out there.
Pretty sure every small block Chev I've seen running around today has had an electric water pump installed

#17 EunUCh

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Posted 04 May 2017 - 07:03 PM

my #s may be quite well and truly wrong but i thought 1HP was around .75KW , 750 watts ?

the lectric all sorts needs power to come from somewhere , if something is hooked up to a battery and wires when it "kicks in" or

is in use then the engine will need to deliver that power via the alternator to keep up with demand (sometimes you can hear the alt. "whirring" under load ), given that lectric fans will only work when needed at some sort of preset then they are probably a good alternative to an engine driven fan , the strange thing is that most water pumps these days are still engine driven , not saying the

lectric ones don't work , just saying , engine speed /water pressure in sympathy with engine speed ?

 

The clutch fans as already mentioned do 9/10's of frokal when cold , they are a strange bit of gear that seem to "follow" the engine temp.

a bit considering that they will only "hook up" once the grease in the hub starts to flow with a bit of temp. , and they do vary with temp.

 

Either way ,6 of one  half dozen of the other.

 

 



#18 LC-GTR-1969

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Posted 04 May 2017 - 09:26 PM

I tested at the drag strip- I run twin thermos, no mechanical fan... 

 

Thermos off- vs thermos on, and compared the terminal mph.

 

Results= zero difference. MPH the same as was ET. 

 

Hence, I would say that electric fans could only draw 1-2hp max as any more would show as a slight change in mph.



#19 StephenSLR

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Posted 05 May 2017 - 06:52 AM

I tested at the drag strip- I run twin thermos, no mechanical fan... 

 

Thermos off- vs thermos on, and compared the terminal mph.

 

Results= zero difference. MPH the same as was ET. 

 

Hence, I would say that electric fans could only draw 1-2hp max as any more would show as a slight change in mph.

 

At what speed do the thermos cut out though?

 

As we know, once enough wind runs through the rad, thermos switch off.

 

s



#20 LC-GTR-1969

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Posted 05 May 2017 - 10:05 AM

At what speed do the thermos cut out though?

 

As we know, once enough wind runs through the rad, thermos switch off.

 

s

 

My fans are on a constant circuit. They are on or off via a remote switch- so an open loop system, hence when they are on they are on- they are not set to cut out at certain wind speeds


Edited by LC-GTR-1969, 05 May 2017 - 10:13 AM.


#21 _Muzzy_

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Posted 05 May 2017 - 07:27 PM

At what speed do the thermos cut out though?
 
As we know, once enough wind runs through the rad, thermos switch off.
 
s


I have my thermos on a 95c cut in and 90c cut out switch. Running a 82 c thermostat .

#22 LC-GTR-1969

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Posted 06 May 2017 - 02:11 PM

I might be shot down here... but I have always heard a lot of knowledgeable people say that running thermos and other electrics like electric water pumps etc, cause an equal increase in parasitic loss through the extra drain on the alternator, as the savings they would give.. in short- the old myth is that the extra alternator drain offsets any hp gained.

This was why I tested my thermo at the strip- but I also fully loaded my electrics (lights, radio, thermos etc) and tested against no electrics- and I saw no measurable gain at the strip- again, whilst I agree there will be some loss of go through the extra drain on the charging system, I believe it's negligible- based on my first hand testing and experience.

In saying that though- I have not tested mechanical fans and so forth, but the results from the video do not surprise me. A big mechanical fan on a small motor will cause greater loss than thermos every day of the week.

Edited by LC-GTR-1969, 06 May 2017 - 02:13 PM.


#23 StephenSLR

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Posted 06 May 2017 - 03:32 PM

I might be shot down here... but I have always heard a lot of knowledgeable people say that running thermos and other electrics like electric water pumps etc, cause an equal increase in parasitic loss through the extra drain on the alternator

 

If your alternator can't cope you get a bigger one, which you'll also need if you're running a sound system with amps, etc. I have a 16" thermo and stock alternator but the alternator gets spun around by the fan belt whether I have the fan or not, it's not like the alternator switches on and puts more load on the engine.

 

s

 



#24 LC-GTR-1969

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Posted 06 May 2017 - 04:18 PM

 it's not like the alternator switches on and puts more load on the engine.

 

s

No, but the argument has been (by others), that the increased demand for energy required by the alternator due to the extra electrical load, causes an increase in the power required to drive the alternator (ie absorbs more hp from the engine when using lots of electrical load). 

 

Remember though, I have proved (at least to myself) that if there is any loss from the extra load on the alternator, it is negligible). 

 

Some interesting reading;

http://www.badasscar...prod/prd101.htm

 

As a side note, I have also tested side gapped and indexed plugs vs just straight up plugs, and the side gapped and indexed gave repeatable improvements, albeit small (like .8mph increase in terminal speed)- so about 4-5hp I reckon


Edited by LC-GTR-1969, 06 May 2017 - 04:25 PM.


#25 StephenSLR

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Posted 06 May 2017 - 05:23 PM

Some interesting reading;

http://www.badasscar...prod/prd101.htm

 

"Just listen to your engine lug down 100 RPM or so when you hook-up some jumper cables to jump start a friend with a dead battery."

 

That makes sense, when my fan switches on it does sound like the engine is doing just that, perhaps not 100 RPM though.

 

s


Edited by StephenSLR, 06 May 2017 - 05:23 PM.





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