Radiator Electric Cooling Fans

TomasL said:
Well, those measurements could be wrong, we dont know really.
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Perhaps one difference is it what you alluded to earlier; this test is measuring the flow after the air passes through the radiator. Typical fan CFM measurements are at no load (no resistance to the airflow, i.e. no radiator). But that is still way too low of CFM to be correct.

By the way, regarding the pressure drop over the radiator, I'd like to compare any fans in a isolation...meaning holding all other variables constant so that the nature of the radiator is not in question. At least for the sake of discussing fans. The radiator design could then be discussed as a separate variable.

I imagine there is something incorrect about the labels on his chart so we are misunderstanding the data. This now makes me wonder about all of it. Although the relative comparison between the different fans tested should still be a general guide as to how they compare to one another, regardless of the numbers. However as I stated earlier this is not a fair comparison because the aftermarket fans he tested are very undersized and not equivalent to the stock fans.

None the less I get the impression the stock fans, if in top condition and proper working order, with sufficient current supplied to them, should provide ample airflow. The problem is none of the six stock fans I have are any of that. We're talking about very old, very worn equipment. Which is one of the main reasons replacement fans are sought in the first place. :)
 
Something else, is that a fan that flows more air than another in open air may not necessarily flow more air when strapped to a load like the radiator. Also, I was wrong about the SPALs I have pulling 10a. The fuse requirement is 15A due to startup, but running current is 6.5A. I had to go to the german SPAL site to find technical information, I guess everyone else is deemed to be too incompetent to read specifications or something.

But that adds yet another layer of complexity since the pressure differential is a function of airflow in the first place.

The cyclone things seem like a cool (ha) option though, admittedly. If paired with a PWM controller as its pretty easy to do, going overkill is okay as you can throttle them back relatively efficiently. All you need is something to read a temp sensor and output a low level 0-5v. There's many, many fan control modules in junkyards for $20 that can then turn that 0-5v into a 0-12v high current signal for the fan itself. Mitsu is the most common but I am sure you can find other external ones from many other makes. Most operate between 10,000 and 20,000hz, which is also great for low noise to prevent PWM ringing (among other bad things).
 
Problem is that they do not publish any fan-curves, 1600 cfm is free-blowing, it could very well be 1,6 cfm with a pressure-drop.
S-curved fans is a new invention, sort of, mainly to reduce noise. However the performance is much lower compare to fans with straight blades.
Fans with straight blades can handle more static pressure, aka pressure drop.
 
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TomasL said:
Problem is that they do not publish any fan-curves, 1600 cfm is freeblowing, it could very well be 1,6 cfm with a pressuredrop.
S-curved fans is a new invention, sort of, mainly to reduce noise.
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It's ridiculous how little quality data there is in the automotive aftermarket.

Occasionally you'll find something, but then you're left to wonder how scientific the testing procedure was. For example, the Davies Craig pump curves look very suspicious to me. Not saying they're wrong, I have no proof, but there's many more examples of cases like that.


Because of that, it's hard to really come to any conclusion. My 348CFM SPALs may outperform many fans rated for 1000+ CFM...under certain conditions and potentially in practice on a radiator, but without testing of course there's no way to tell.

Calculating necessary air flow for a given heat rejection is of course simple as well with an EWP once you know the coolant flow rate, which shouldn't be difficult to do one day.
 
TomasL said:
It seems that ell of them is selling snake-oil, more or less.
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And occasionally they land on something that works well but "why" isn't known.


It seems that's how many aftermarket engine performance upgrades are too. I've found many, many flaws in "tuners" "explanations" as to why various upgrades provide the benefit they do over the years. Lots of that in the Abarth 500 community...


Sorry to diverge the thread again lol
 
Sorry, had no time until now.
Tomas did a great job of translating the data.

Is there anything else I should translate or clarify with the german author?
 
Ulix said:
Sorry, had no time until now.
Tomas did a great job of translating the data.

Is there anything else I should translate or clarify with the german author?
Click to expand...
If you are in contact with the author, possibly he can help understand why the data for airflow equate to such low values when converted to CFM? :)
 
But what are you comparing the measured results to?
We don't have CFM figures for a Spal fan blowing through a typical radiator, do we?
Just imagine the free air flow of the fan and now imagine having to move that volume rate of air through that radiator core.
The core is a MAJOR obstruction.

And to get really accurate numbers for the whole fan, you probably wouldn't choose to measure individual spots, less than 1" diameter, across the radiator and try to calculate the total volume flow from that.
 
Although the accurate numbers for the whole fan are unlikely to be entirely correct based on a limited number of tested locations, as long as the various fans tested are done in the same way the information garnered is comparable fan to fan and is therefor pertinent in understanding the actual performance if not the actual total throughput of the fans.

An actual test is worth much more than all the opinions in the world. Americans seem to have forgotten that in the modern era.
 
I intended to mention this previously. A possible fan option for a robust and very high volume fan at a reasonable price is a stock VW item. It is about 12" so you would need to add a shroud to control the air going across the radiator rather than around it...which should be done with any fan. If you also use the VW radiator option I discussed in another thread then there is a shroud made for this fan with that radiator. Most likely the best source for that shroud is a wrecking yard. The fan is a two speed unit so any of the dual temp VW sensors can be installed in the radiator (Fiat or VW) and wired directly to it. The motor is rated at 250 watts for the slow speed and 350 watts for the high speed. The blades are a curved wide paddle design. This is a beast. I've seen them listed for around $50 (aftermarket) and up. The VW part number is: 1H0959455G. Like all VW parts there's also several other part numbers for it.

Here's a couple pics of what it looks like.

1H0959455GPic2.jpg
1H0959455G.jpg
 
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