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Making sure which fan to use.
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=76071		 Page 1 of 1
Author:  Auberon [ Tue Jul 23, 2013 6:21 am ]
Post subject:  Making sure which fan to use.
Supposition re these fans doesn't help.
I will will test between 52079654AD (plastic from the petrol (gasser) fan) & the metal fan currently fitted to the vehicle.

1 Have a plastic fan arriving in the next few days.
2 Need to know for sure before I install either one.
3 Have no current issues re extraneous operating temperature - don't want them
4 Seeing only one way to do this.

I plan to:
run it in my lathe or use a lay shaft to mount it and produce an output curve in a properly designed experiment that will be determined with a 95% statistical certainty.
- a mathematically determined yes or no answer as determined by the [i]t[/i] test determining actually which fan has the greatest output and what it is at given speed of rotation.
- validate speed using a known to be good tachometer.
Comment: Before it's said I have 11" swing over the bedways (at the gap).
Rotation speed will be verified by known speeds of the gearbox @ 50Hz.
Author:  Lancer [ Tue Jul 23, 2013 5:35 pm ]
Post subject:  Re: Making sure which fan to use.
HI Auberon, I'll be interested to see the results! I still think you're a show-off though :lol:
Author:  ATXKJ [ Tue Jul 23, 2013 5:55 pm ]
Post subject:  Re: Making sure which fan to use.
He might be a show-off - but if he gets data - it still a good thing.

might also try to measure current - so that you have the power required to produce the air flow.

I suspect the metal fan will push more air at higher speeds - but requires more power to get there.

However - unless you're towing - I don't think the metal/plastic fan matters.

from an old thread
LibertyCRD wrote:
We just came through our hottest Summer on record here in Kentucky. In August, temps. outside were regularly in the 100°F range with heat index temps. in the 115-125°F range for weeks on end.

Not one single time did my temperature gauge in the Jeep ever go above half-way...and that is with NO fan whatsoever. Once, while towing 7,000 lbs. uphill in Tennessee it did go about 3/4 scale...but that's to be expected. Running with no trailer is no problem with no fan in any weather. So I'm sticking with the cheap route, and throwing the fan in the garbage.
Author:  TJ2 [ Tue Jul 23, 2013 8:11 pm ]
Post subject:  Re: Making sure which fan to use.
ATXKJ wrote:
He might be a show-off - but if he gets data - it still a good thing.

might also try to measure current - so that you have the power required to produce the air flow.

I suspect the metal fan will push more air at higher speeds - but requires more power to get there.

However - unless you're towing - I don't think the metal/plastic fan matters.

from an old thread
LibertyCRD wrote:
We just came through our hottest Summer on record here in Kentucky. In August, temps. outside were regularly in the 100°F range with heat index temps. in the 115-125°F range for weeks on end.

Not one single time did my temperature gauge in the Jeep ever go above half-way...and that is with NO fan whatsoever. Once, while towing 7,000 lbs. uphill in Tennessee it did go about 3/4 scale...but that's to be expected. Running with no trailer is no problem with no fan in any weather. So I'm sticking with the cheap route, and throwing the fan in the garbage.


Well, it's 97* F on my porch at this moment. I live as the base of a mountain pass (formerly used mainly to drive sheep the shortest distance.) The climb is a little over 2k ft in 2 miles. The curves are sharp meaning speed (in a CRD) can't get over about 35 mph.
Utah mountain/desert is not Tennessee. Man, would I like to have some you 'no fan' guys out here. . . right now.
Author:  DOC4444 [ Tue Jul 23, 2013 10:25 pm ]
Post subject:  Re: Making sure which fan to use.
The Hayden clutch cuts in at a much lower temp tha the OEM clutch I removed, so I went with the lower CFM nylon fan to try to regain some mileage lost by the earlier cut-in.

For extreme towing conditions, the OEM metal fan moves the most air.

DOC
Author:  CATCRD [ Tue Jul 23, 2013 10:28 pm ]
Post subject:  Re: Making sure which fan to use.
I hope you are able to use a shroud during the experiment. Could affect different fans differently. In my experience, the closer your setup is to the actual configuration, the more meaningful are your results.
Author:  Lancer [ Wed Jul 24, 2013 4:27 am ]
Post subject:  Re: Making sure which fan to use.
Auberon always adopts a scientific approach to his tests.
Author:  Auberon [ Wed Jul 24, 2013 5:52 am ]
Post subject:  Re: Making sure which fan to use.
Thank you for the vote of confidence Lancer. Showing off NAAH! I'm just scientifically retentive (read A_____Y Retentive) I bored the down out of my nannas' feather bed. :shock:
Just trying to give something back to all those chaps who've helped me with so much entertaining reading and a good belly laugh.

Of course, this will be done with absolute regard to reducing variables. So it would have to be shrouded - if necessary, I'll take the fan shroud off my Jeep to do it but I would rather not. It could NOT be done without a shroud as radial losses would chuck it out the window. It will at least be a close copy.
and
It will be done as a gradient from outside diameter to center (if that is feasible) at a constant distance from the impellor.

[u][u]Power[/u][/u] is not possible to determine through electricity consumption as gearbox losses vary with each gear selected - I only have 9 gears and go through and a double V belt drive. As speed increases, frictional losses are too great. I am trying to avoid fabbing a lay shaft drive if I can. This will give me 9 points to plot a decent curve output curve from

These will have to be "free air" measurements.

I will only be able to conduct this in the ambient conditions that prevail at the time I make the measurements and I will provide what I can with my results.

I have some guidance in that Keith has stated somewhere in the forum that 4000 rpm is towards the top speed that the fan coupling runs at. I guess it would be nice to see how many rpm the engine is doing at each fan speed. This is not an experimental engine so I will not flog it. 2400 engine rpm seems OK as an upper limit to me but fan sped at that (if I can even get it hot enough to measure). I figure measuring the rpm of the pulley for 1:1 coupling will do.

There are some displacement numbers for the metal fan floating about but this ifs what I aim at confirming. I have no idea how this will end up but it interesting.
We will all have a basis for comparison.
Happy to admit funds are definitely limited.

Please remember that the variables behind each and everyone's front grill is different - heck even in front with high mounted winches like mine.

Sorry chaps but free flowing air with no resistance is the best you get - and if you are buying a fan that is all you get in performance figures. Your engineering intuition interpolates to your application.
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