Slant Six Forum :: Cooling fan

For those of you still running a fixed fan on the front of your slant, watch this video.

https://www.youtube.com/watch?v=ZXdLgaFXZzs

Quote:

For those of you still running a fixed fan on the front of your slant, watch this video.

https://www.youtube.com/watch?v=ZXdLgaFXZzs

Sorry that video is IMO, a highfalutin glittered shade tree mechanic exercise, and not much more. I think we all can agree it takes x amount of air mass at a given y velocity to remove z amount of thermal energy (the whole point). Only result of this video is to compare amount of horsepower needed by the tested fan to reach an unknown x and y,, and not much more. I label it. "mostly irrelevant entertainment"

Did I miss how the thermal clutch fan was activated, or did it just get tested in its static mode?

The clutch fan should be disengaged at high rpm's

Quote:

they do not point out the fact that an engine make significantly less hp at those lower rpms. Taking less from less is still a big loss.

Not really; air resistance rises exponentially with speed and engine output does not. So a fan takes a much, much smaller bite out of power at lower speed than at higher speed.

Also, this cannot be harped on enough: electric fans do not run "for free". It takes a certain amount of work to move a certain amount of air across the radiator. Whether the energy to do that work is put into the fan directly by a pulley spun by a belt driven by the engine's crankshaft, or by a motor powered by electricity generated by the alternator spun by a belt driven by the engine's crankshaft, that work is going to come from the engine. The advantage of an electric fan is that it runs only when needed (as determined by coolant temperature), not that it somehow does its work without exerting a load on the engine.

Quote:

The clutch fan should be disengaged at high rpm's

...if it's a centrifugal clutch (the dumb/cheap kind). A thermal fan clutch (the non-stupid kind) responds to air temperature, not rotative speed.

Quote:

For those of you still running a fixed fan on the front of your slant, watch this video.

https://www.youtube.com/watch?v=ZXdLgaFXZzs

Yeah, how much horsepower each type of fan takes to run is exactly to point of the video. Good catch.

The clutch fan should be disengaged at high rpm's. If it is engaged, then it would be the same as a fixed fan.

Quote:

Sorry second time, if this is sarcasm, its not clear.

A fan ii supposed (?) to cool an engine by moving a needed amount of air at a needed speed. The size/positioning/fan design/fan speed/etc all factor in to achieve that. Since these factors also effect the efficiency of that process, it also effects the hp consumed to achieve the needed cooling. Over cooling is likely wasteful. The video only compared 4 fans of same size, and never controlled for any cooling capacity (air mass/speed), the point of a fan. If how much hp used is the ultimate goal here, don't run one, or run an electric with no alternator.There are situation's in the 1/4 mile you might just be fine, but not realistic.

If an engine is at high rpm's, the vehicle should be running at a high speed

I can think of plenty of situations where that's not the case.

Author:	SlantSteve [ Sun Jun 25, 2017 7:07 pm ]
Post subject:
I really doubt airflow speed into the fan would make any measurable difference. Taken to extremes a fixed pitch prop on a light aircraft,about 5' diameter will pull say 2400 rpm full power static. On the take off roll it would usually climb to say 2600 at about 100 mph,and that's a huge diameter compared to the tiny cooling fans on cars. Yes,there's a difference in power needed to spin it but very small. It's actually possible ,depending on fan blade design that the engine fan can actually restrict airflow at higher vehicle speeds,they are at best a compromise.Electric fans are simply efficient,they operate at their design rpm when needed,which is usually at low vehicle speeds,right where the engine driven fans are at their most inefficient. Yes,of course they consume power,but they use that power in an efficient manner. These guys do some great videos, but they are measuring power outputs,there are many other benefits of going electric.

Author:	mopar_nocar [ Mon Jun 26, 2017 8:37 am ]
Post subject:	What e-fan to get then?
Ok, so the junk fans at the FLAPS will not cool anything. What is the best fan to get? I have not had great luck, even when paying some $ for a fan/relay/temp sensor set up. sb

Author:	coconuteater64 [ Mon Jun 26, 2017 9:49 am ]
Post subject:
DadTruck is using a dual fan set up from IIRC a Caravan (I may be wrong) and reports having no trouble. I have a NOS Saturn fan and it never gets hot in heavy traffic on I-75 during the dog days of summer in Georgia, where it can get over 100 degrees with near 100% humidity. As for aerodynamic improvement, I cannot say if fixed versus electric is any better. But our vehicles are as aerodynamic as a barn anyway.

Author:	Reed [ Mon Jun 26, 2017 9:50 am ]
Post subject:
You can find some nice setups from the junkyard like fans that come with fan shrouds, just try and find one that fits your radiator. Otherwise just look for a good deal on ebay, Craigslist, or at a swap meet.

Author:	jcc [ Mon Jun 26, 2017 11:37 am ]
Post subject:	Re: Cooling fan
Quote: For those of you still running a fixed fan on the front of your slant, watch this video. https://www.youtube.com/watch?v=ZXdLgaFXZzs Sorry that video is IMO, a highfalutin glittered shade tree mechanic exercise, and not much more. I think we all can agree it takes x amount of air mass at a given y velocity to remove z amount of thermal energy (the whole point). Only result of this video is to compare amount of horsepower needed by the tested fan to reach an unknown x and y,, and not much more. I label it. "mostly irrelevant entertainment" Did I miss how the thermal clutch fan was activated, or did it just get tested in its static mode?

Slant Six Forum https://slantsix.org/forum/

Cooling fan https://slantsix.org/forum/viewtopic.php?t=61296	Page 2 of 5

Author:	afastcuda1970 [ Mon Jun 26, 2017 2:13 pm ]
Post subject:	Re: Cooling fan
Quote: Quote: For those of you still running a fixed fan on the front of your slant, watch this video. https://www.youtube.com/watch?v=ZXdLgaFXZzs Sorry that video is IMO, a highfalutin glittered shade tree mechanic exercise, and not much more. I think we all can agree it takes x amount of air mass at a given y velocity to remove z amount of thermal energy (the whole point). Only result of this video is to compare amount of horsepower needed by the tested fan to reach an unknown x and y,, and not much more. I label it. "mostly irrelevant entertainment" Did I miss how the thermal clutch fan was activated, or did it just get tested in its static mode? Yeah, how much horsepower each type of fan takes to run is exactly to point of the video. Good catch. The clutch fan should be disengaged at high rpm's. If it is engaged, then it would be the same as a fixed fan.

Author:	SlantSixDan [ Mon Jun 26, 2017 3:22 pm ]
Post subject:	Re: Cooling fan
Quote: The clutch fan should be disengaged at high rpm's ...if it's a centrifugal clutch (the dumb/cheap kind). A thermal fan clutch (the non-stupid kind) responds to air temperature, not rotative speed.

Author:	NEVjr [ Mon Jun 26, 2017 3:26 pm ]
Post subject:
Quote: Quote: they do not point out the fact that an engine make significantly less hp at those lower rpms. Taking less from less is still a big loss. Not really; air resistance rises exponentially with speed and engine output does not. So a fan takes a much, much smaller bite out of power at lower speed than at higher speed. Also, this cannot be harped on enough: electric fans do not run "for free". It takes a certain amount of work to move a certain amount of air across the radiator. Whether the energy to do that work is put into the fan directly by a pulley spun by a belt driven by the engine's crankshaft, or by a motor powered by electricity generated by the alternator spun by a belt driven by the engine's crankshaft, that work is going to come from the engine. The advantage of an electric fan is that it runs only when needed (as determined by coolant temperature), not that it somehow does its work without exerting a load on the engine. the largest dual fan setup i can see on summit draws 48A and moves 6800 cfm, that's 576 watts or about 0.8 hp, your alternator is say 50% efficient, that's still less than 2 hp of drag at max fan speed for a massive fan

Author:	afastcuda1970 [ Mon Jun 26, 2017 4:04 pm ]
Post subject:	Re: Cooling fan
Quote: Quote: The clutch fan should be disengaged at high rpm's ...if it's a centrifugal clutch (the dumb/cheap kind). A thermal fan clutch (the non-stupid kind) responds to air temperature, not rotative speed. If an engine is at high rpm's, the vehicle should be running at a high speed and the incoming air will be cool enough to disengage a (non-stupid kind) clutch fan. If not, there is probably other problems with your cooling system.

Author:	jcc [ Mon Jun 26, 2017 4:31 pm ]
Post subject:	Re: Cooling fan
Quote: Quote: Quote: For those of you still running a fixed fan on the front of your slant, watch this video. https://www.youtube.com/watch?v=ZXdLgaFXZzs Sorry that video is IMO, a highfalutin glittered shade tree mechanic exercise, and not much more. I think we all can agree it takes x amount of air mass at a given y velocity to remove z amount of thermal energy (the whole point). Only result of this video is to compare amount of horsepower needed by the tested fan to reach an unknown x and y,, and not much more. I label it. "mostly irrelevant entertainment" Did I miss how the thermal clutch fan was activated, or did it just get tested in its static mode? Yeah, how much horsepower each type of fan takes to run is exactly to point of the video. Good catch. The clutch fan should be disengaged at high rpm's. If it is engaged, then it would be the same as a fixed fan. Sorry second time, if this is sarcasm, its not clear. A fan ii supposed (?) to cool an engine by moving a needed amount of air at a needed speed. The size/positioning/fan design/fan speed/etc all factor in to achieve that. Since these factors also effect the efficiency of that process, it also effects the hp consumed to achieve the needed cooling. Over cooling is likely wasteful. The video only compared 4 fans of same size, and never controlled for any cooling capacity (air mass/speed), the point of a fan. If how much hp used is the ultimate goal here, don't run one, or run an electric with no alternator.There are situation's in the 1/4 mile you might just be fine, but not realistic.

Author:	Reed [ Mon Jun 26, 2017 4:54 pm ]
Post subject:
I would have liked to see what change, if any, resulted from doing those same test without and then with a high powered fan blowing across the cooling fan. And then the smae tests with a fan and a thermostatic controlled switch on the electric fan and an thermostatically controlled clutch on the clutch fan.

Author:	afastcuda1970 [ Mon Jun 26, 2017 4:55 pm ]
Post subject:	Re: Cooling fan
Quote: Quote: Quote: Sorry that video is IMO, a highfalutin glittered shade tree mechanic exercise, and not much more. I think we all can agree it takes x amount of air mass at a given y velocity to remove z amount of thermal energy (the whole point). Only result of this video is to compare amount of horsepower needed by the tested fan to reach an unknown x and y,, and not much more. I label it. "mostly irrelevant entertainment" Did I miss how the thermal clutch fan was activated, or did it just get tested in its static mode? Yeah, how much horsepower each type of fan takes to run is exactly to point of the video. Good catch. The clutch fan should be disengaged at high rpm's. If it is engaged, then it would be the same as a fixed fan. Sorry second time, if this is sarcasm, its not clear. A fan ii supposed (?) to cool an engine by moving a needed amount of air at a needed speed. The size/positioning/fan design/fan speed/etc all factor in to achieve that. Since these factors also effect the efficiency of that process, it also effects the hp consumed to achieve the needed cooling. Over cooling is likely wasteful. The video only compared 4 fans of same size, and never controlled for any cooling capacity (air mass/speed), the point of a fan. If how much hp used is the ultimate goal here, don't run one, or run an electric with no alternator.There are situation's in the 1/4 mile you might just be fine, but not realistic. They were not testing the cooling capacity of each fan. They were testing to see which type of fan consumed the most horsepower. They were not trying to get an exact hp figure as much as fan A consumes the most hp and fan D consumes the least. Due to how an engine dyno works, they cannot use a radiator to cool the engine and test the fans efficiency. A proper test would be each fan installed in a car on a chassis dyno inside a wind tunnel. I'm sure their magazine editors would not be willing to fund such a project. Take what you want from the video or take nothing at all, it's your choice. I thought that I was posting useful information but your mileage may vary.

Author:	SlantSixDan [ Mon Jun 26, 2017 5:48 pm ]
Post subject:	Re: Cooling fan
Quote: If an engine is at high rpm's, the vehicle should be running at a high speed I can think of plenty of situations where that's not the case.

Author:	Rick Covalt [ Mon Jun 26, 2017 5:49 pm ]
Post subject:
I like the electric fan for two main reasons. 1- I don't have to worry about cutting my fingers off! 2- I like the extra room I get between the radiator and the water pump by putting them in front of my radiators. And for the 13 seconds I go down the drag strip I just turn the electric fan off. No electric consumption!

Page 2 of 5	All times are UTC-08:00
Powered by phpBB® Forum Software © phpBB Limited https://www.phpbb.com/

Author:	afastcuda1970 [ Mon Jun 26, 2017 6:26 pm ]
Post subject:	Re: Cooling fan
Quote: I can think of plenty of situations where that's not the case. In those situations the "stupid type" clutch fans would be more efficient than the "non-stupid type" clutch fans.