Ebay slim fan performance vs Spal
 

Well here's a little info for you guys. I don't have a means to measure CFM, so some of this is subjective. But maybe this will help somebody with their fan choice down the road.

I just bought these Ebay 12" Slim fans: 2 x Universal Slim 12" Pull Push Radiator Engine Bay Cooling Fan Mounting Black | eBay

They are rated at 12V, 80W, 1730 CFM, straight blade. I have a pair of them.

I used a battery charger to keep keep the voltage at 14.5V during testing.

I tested one of them:

in free air
sitting flat on an a/c condenser
and then 3/4" away from the surface of an a/c condenser with the fan sealed to the condenser.

These fans, in free air, are not very impressive. They might move 1,000-1,200 CFM. No way in the world they move 1700 cfm.

With them sitting flush on the a/c condenser only, yeah.... maybe 1/3 the airflow. The only part of the fan moving much air is around the edge of the fan, towards the middle it's doing almost nothing.

With them 3/4" away from the surface, about 1/2 the airflow, maybe a bit more. Big improvement vs having it rest against the heat exchanger.

If drug a piece of paper around the backside in different spots, during the test, and it's about what you'd expect. With the fan flush on the condenser, it pulls more pressure, but only in the "ring" of the fan blades, none on the edges or the center of the fan.

With the fan 3/4" off the radiator, it's much more even. I think 3/4" is probably the minimum for a shroud to be effective, 1" is probably better still but I think the minimum should be 3/4".

Interestingly, the fans pulled 0.7 Amps more when sitting flush on the condenser vs 3/4" off the condenser (7.5A vs 6.8A). In free air they are 6.7A.

The ac condenser is 3/4" thick at the core.

For reference, I have a pair of spal extreme performance 12" fans on my radiator, and subjectively, they move 4x the airflow when bolted to my radiator vs these ebay fans, at the same voltage. Spals pull 30-32A each though, these ebay fans only pull about 6.8A each. And the radiator is thicker, and has a higher fin density, so therefore more resistance to airflow vs an a/c condenser. The SPAL fans really are good fans.

Based on what I'm seeing, it looks like Amps and Airflow are pretty linearly related when comparing fan CFM when bolted to a heat exchanger. And it looks like the ebay fans I bought are pretty weak. My guess is I'll probably end up swapping these ebay fans for something better down the road, but for now I have them and am going to give them a shot.

Also it appears that if you're gonna mount a fan without a shroud, if you could still mount it 3/4"-1" off the radiator, and seal it only where it would normally contact the radiator, this would improve fan performance without the air flow penalty at speed that you get from a conventional fan shroud.

A radiator shroud with lightly weighted flaps that blow open at speed yet fall closed for "vacuum" at idle would likely be ideal, but I doubt even that is necessary.


https://www.miataturbo.net/attachmen...ine=1434676703



Cooking pans make excellent 3/4-1" offset shrouds too, slice and splice the things to fit.

https://www.miataturbo.net/attachmen...ine=1434676703


I haven't got to the real hot weather yet, but I don't seem to have heat control problems at idle or low speed conditions. I'm using the factory smaller condenser fan only, and it's not shrouded or sealed against my radiator much at all.

I've been considering using a cooking tin and cheap ebay fans in the slim space I've got between the swaybar. I imagine two in tandem ought to be fairly close to the stock condenser fan, would you agree?

Thanks for the post!

I can't recommend these ebay fans I'm using for a radiator, they are a lot worse than the stock fans. I doubt they would pull 1/2 the air the stock fans will. Stock fans are pretty decent and they have a built in shroud which is nice.

I'm doing a rear-mount a/c condenser and for this, I need a very thin fan for packaging. If I had the space, I'd probably run a pair of stock fans given how cheap they are and how well they work. For this they just would not fit though.

Quick update on the fans....

So I decided to cut some of the webbing out of the fans to see if it would help improve airflow. It did, so I ended up cutting all of it out. This surprisingly makes a BIG difference! I'd say at minimum, the fans are moving 25% more air. It's a pretty good difference, certainly significant. I just used a sharp knife, it's plastic so they cut easy, takes about 6-8 minutes to do one fan being careful. I didn't test the current, but I'll do that tomorrow to see if it changed from cutting the fans.

Also worth noting the way the fans are now supported is how my SPAL extreme performance fans are made.

If you run slim fans and they are marginal, this could make a difference! More cooling is always better.

https://www.miataturbo.net/attachmen...ine=1434697810

http://i231.photobucket.com/albums/e...psyjn1kz7p.jpg

Rear mount a/c condenser pics will be in my build thread.

like 10 years ago we all decided the stock fans were better--you are continuously posting stuff we did a long time ago. Sucks you had to miss out on learning trying to fuck Rick over with Homemadeturbo.com and making him regret his 5 figure purchase of the site.

I don't just assume that whatever this forum believes to be true is 100% correct 100% of the time. I test things and see for myself.

And sometimes I post what I've learned. Why would you have anything negative to say about that? This is a miata forum and a lot of people here want to build a better miata.

I could give 2 craps about politics, Rick, his finances, HMT, you, or what anyone on this forum or that forum thinks about my post. I'm here to talk miatas and learn, making them faster and more reliable.

I stuffed an ebay fan into a stock shroud and it seemed to work well. the shrouding is MUCH better than the direct mounts.

Im not surprised by your finding on cutting away all that material behind the fan.

But I'm still in the "use stock fans" camp unless you actually cant fit them.

I read that thread before starting this one. Agreed shrouding is important.

I never found anyone who cut the material off the fan to test that and posted about it. I just looked at it and damn, the plastic blocks probably 20-30% of the area, it's a lot! My SPALs aren't like that so I figured why not and started cutting.

I remember a long time ago Jason posted that a shroud should be 1" away to be effective. My test shows 3/4" is usable if you need the space, but less than 3/4" really hurts performance. My shroud is 1".

EDIT: And yes I agree, use stock fans vs these if at all possible, even as they are now these ebay fans don't move the air a stock fan does. I have another '99 miata to compare to that's stock, and the stock fans on a stock radiator are for sure better.

Your Spal's also probably also have beefier support ribs that what is left after you cutting up the cheap fans. I would be worried about one of those remaining ribs breaking and sending a cheap fan into what is hopefully a decent radiator. Although if you are going cheap on non-Spal ebay fans, I doubt the radiator is anything better than cheap ebay as well.

Yeah the spals are much beefier, but have less total ribs. And they are made from fiberglass too, not plastic.

Still I tried bending the motor on the ebay fan, and the motor does move, but it moves where it's bolted to the plastic hub in the center. If I twisted enough, I think I'd break the 2 tiny plastic spots that hold the motor to the plastic hub int he center. So the ribs should be ok but we'll see.

These fans are going on an a/c condenser located in the rear of the vehicle. And it's a cheap a/c condenser. :) Only reason I bought them is because I need a thin fan, I was actually hoping to use stock fans but when I measured there was no way... If these don't cut it, I'll buy some SPAL fans down the road. But I actually just tested these fans on my new shroud, and they're..... ok. Not bad once the shroud was finished. For an a/c condenser I think it will be alright, but it will be a bit before I know for sure.

i did this in 08 fwiw
https://www.miataturbo.net/attachmen...ine=1434839416

Here is the custom shroud I had fabricated, that includes SPAL fans (12" 1225 CFM 140 watt - from memory). On the track the temp does not go above 95 deg c when used as a daily drive stop start traffic has very little effect on the temp. Only mod that needs to be done is seal around the radiator so that all the air goes through it and not around.

https://www.miataturbo.net/attachmen...ine=1434841356

https://www.miataturbo.net/attachmen...ine=1434841356

https://www.miataturbo.net/attachmen...ine=1434841356

Here's my set up using Spal 30101504(12", 1097 CFM each):

https://www.miataturbo.net/attachmen...ine=1434841816

Here are the SPAL fans on a modified FM shroud I run on my MSM Radiator.

https://www.miataturbo.net/attachmen...ine=1413233473

https://www.miataturbo.net/attachmen...ine=1413233473


And here's the Ebay fans on my custom shroud

http://i231.photobucket.com/albums/e...ps9iydkshx.jpg

How did it work? How did it compare to stock fan? Looks identical to the fans I bought.

It was an ebay fan, so it was mediocre. CAr never overheated so there's that, but I wasn't too happy with it. Definitely wasn't an improvement over stock
The only reason I ran it on my 1st setup is cause I was space limited and needed something slightly slimmer than the stocker

Alright - so i have to do something here. My NB overheats when i have the ac on - or on track after 3 laps. That's at 92f ambient temps. Last night, after struggling with track temps sat, i installed trackspeeds dual pass radiator i had bought for the track car. It helps some, but not enough.
Objects of airflow resistance - begi #3 ic, factory ac condenser, TSE dual pass, reroute, hood vents, no ducting, running single 12" egay fan.
I was surprised it was overheating cruising on the interstate at 80 when i kicked on the ac - which i ain't about to settle for when it's 95f outside.
Now, i can duct, which i will, but what else - better fan? Run dual 12" fans on a shroud? (You can't fit dual 12" on the tse rad), high flow ac condenser?

Ducting ducting ducting.

If you're overheating at idle, or below ~25mph, you need better fans. Above that, ducting.

BTW ducting is only gonna work so well when there are 3 heat exchangers up front. I recently just pulled the a/c condenser and moved it to the rear as I've struggled for years to get enough air to the radiator with 2 other heat exchangers blocking it.

The shrouding on the ebay fans is there to prevent finger removal, not so much strength. My silicone intakes fans have it too, they pull 8 amps when mounted directly to the radiator based on my clamp meter, they're rated for 6 amps. The blades look the same as the Spal fans Epifan has but the housing is different. Interesting that you managed to get that much more flow from cutting them out. I'll have to try it on mine, new ones are cheap enough if I screw them up.

I just used Pat's cut away the finger-protectors trick on a condenser fan setup I just built -- although I only cut away half of the structure, not all of it. Jeg's heavy duty slim-fan, which are slightly more expensive than the mid-grade Spals and rated a little higher. Wish me luck, although at the rate I'm going the weather will be cool by the time I'm driving.

https://www.miataturbo.net/build-thr...8/#post1242422

Do this and report back. I've noticed that my NB seems to have A LOT more areas of air leakage than my NA ever did. I suspect you will find huge dividends with even half assed ducting compared to what the factory gave us.

Will do!

Cheapie fans just lost torsional rigidity. Try twisting the motor by hand...

These motors would have to make some measurable amount of torque for that to matter....

Its not the motor torque that is the problem its when you go down the road over a bump and those fan blades get pushed into the radiator.

uh huh.

Well gentlemen, I can tell you the particular fans I did this to, that's not going to be a problem. The motor on these fans is very light. Besides, I mounted then 1" away, they'll never touch. Also by design the fan blades are around 3/4" away from the shroud anyways, so even if you mounted the fan directly to the radiator, the fan blades still would never hit the radiator.

Can't wait for the follow up thread in 3-6 months when you being a cheap ass nukes your radiator.

I hope they don't nuke my radiator, we will have to see! I'm sure you guys know more about my setup than I do though, so I trust you are right!

If it's really a concern why not leave 4 sections untouched to keep some strength.
https://www.miataturbo.net/attachmen...ine=1435087803

Because it's a concern that's not actually a problem.

See the two screws in the pic of the motor at 9 and 3 O'clock? That's all that hold the motor the the plastic-hub it's bolted to. If I grabbed the fan blade and started pulling/twisting, I'd break the fan where those 2 screws are. That is the weak link, not the little ribs. I compared both fans in the pic, both would break there first, it's the obvious weak point. So if I want to make it stronger, I need to improve that, not the ribs.

And FYI, I did it by removing 1 section (proved that removing ribs increases airflow), then 4, then 8, then 10, then all 12. Each time it showed the mounts for the motor were flexing. So I kept cutting. I'm sure it's weaker, but I doubt it will be a problem. Even if it is, so what, they were like 37 dollars shipped for the PAIR!

I'm totally on your side. I have those exact same fans on mine, and am needing better airflow as well with the Texas heat. I was just curious if you'd removed them in groups or all in one go. Thanks for doing the research for me!

If those ribs hurt airflow that much, imagine how much a radiator would!!

Just went out into the office parking lot and broke all but 4 of my supports out. I can also confirm that the fan motor/body is no more flexible than before I started. I'm anxious to see if it improves my overheating in traffic with the AC on.

What exactly is your point? Pulling air through a radiator is the point. Pushing air past extraneous plastic supports, not so much.

It is what it is, sub $40 pair of fans. If this makes them suck less and still keeps the car from overheating at idle it is a win.

I'll be leaving for home shortly in 93* Dallas traffic. I'll report back on if removing fins helped me.

Exactly, an odd post from Jason.

It has to help some, and it doesn't seem to hurt anything. Either way my goal is to make things work better, so even if the motor falls off the fan tomorrow and it becomes obvious I caused it, that's ok. Nobody knows everything, and I certainly don't.

If you look at any high quality fan, the little keep-your-finger-out-ribs are much thinner than the ebay fans. Some in this thread show that SPAL fans for example are thinner even if they have them too.

Besides I just knocked at least 10 grams off the fans, so gram strategy make me go faster! :rofl:

In for results.

This thread made me switch out my supposed spal fans (ended up not being spal fans) to the stock units. Need to run some logs to see if there is a difference.

So my temp was 199-201 crusin on the highway, about 3* lower than normal, no ac. Mostlikely caused by reduced restriction for air going through the shroud. I turned my ac when traffic got to less than 10 mph on the highway, I made it about 3/4 of the way before temps got to 218* and I shut it off. Normally I make it less than halfway before temps got that high. I addition the Temps came back to 205* very quickly, before I had to turn the heater on to drop the temps.

Awesome glad it helped some! Still not ideal temps with a/c on but any improvement is good.

I'm currently running no front bumper, no ducting, and no undertray, so hopefully when I address those three it will sort it out. What's weird is that I can park my car in a parking lot and let it idle "all day" with the ac on without overheating. It only overheats when I get in stop and go traffic.

rofl. go fuck yourself.

:bowrofl:

I removed the engine and car stopped overheating.

When i don't drive my car, it doesn't overheat.

Patrick it sounded like you are measuring the airflow coming out of the fan? Would it be more useful to know the airflow going into (and as such through) the front of the radiator? Spacing the fans out from the rear face of the radiator may not be a direct representation of the airflow pulling heat from the coolant but a bypass. We get this in industry sometimes, and even have a recirculation effect when customers don't seal off a radiator shroud properly

It would be great if you could retest this!

Well, considering I just got my turbo installed and am working on trimming everything up to fit around it, I think that is acceptable.

Thanks to this thread, i removed my fake Spal fans and re installed the OEM fans. Now they cycle off instead of staying on trying to just maintain current temp. I even tested and eventually used the a/c last night. Win!

yup.

A quick review. last year my stock fan came in contact with my sway bar. things happened and the the oem fan was toast. being that I was stranded at an autozone I picked up the autozone $50 special. rented 10mm and wire cutters, zip-tied the thing in place and headed home. car ran 5* cooler then with the stock fan. went back a week later and bought another one. works great.


https://www.miataturbo.net/attachmen...ine=1435242979


Picture of the car overheating at autozone.

sorry you needed a fan just to maintain normal operating temps...

most cars need fans to maintain operating temps. think about traffic bud.

the oem fan never worked that great. it would kick on and wouldn't keep a constant temperature. with two of these little suckers water temp never gets over 200*

On my 99, if I keep the a/c off, and the temps are say 90 or below, and I'm "driving normal", if I catch a light, I can idle for about 3-4 minutes until the fans switch from low (a little air flow) to high (70A worth of airflow). With a/c on, the fans will turn on high a lot sooner and run a lot longer. When my ducting sucked, the fans ran just cruising down the highway though, since the radiator couldn't get enough airflow with my (at the time) less than ideal ducting.

I think having fans on a street car is important. I think this is why street cars have fans. But if your setup is pefect, the fans are pretty much for idle, low speed, a/c blasting conditions. On the highways they shouldn't need to run. Racing on a track, no idea.

Take your fans off your car and roll on the highway and see what happens.

Why? I'm happy with the cooling system for now. On my car pulling the fans is a huge pain, so probably not gonna happen unless I really think I need to.

It would potentially/probably illustrate a point that Keith has made a few times in the cooling thread.

I've only had one Miata NOT cycle fans on the highway. And that one didn't cycle the fans because it had that dumbass Begi Racer bullshit on it.

What would be the point to illustrate? Sorry I'm not catching it...

My fans run on "low" all the time. They get ~6V each. They do more air on low, but only about 1/3 the amount they move on High when they get full power.

Now that I've finally got my cooling system for the radiator sorted, I'm thinking of adding the wiring necessary to allow me to shut the fans off. I know it sounds simple to you, but I have a series/parallel/time delay setup I made and I have to add another relay to make it possible to turn the fans off while the key is on, but the time delay low work when the key goes off.

Basically my plan is to electrically unhook the fans on a really hot day and see what happens on the highway/city speeds. If it's obvious them being off is ok, then I'll make the wiring changes necessary as that will reduce wasted electrical power and not wear my fans out as quickly.

<p>My temps don't go above 190 at any point ever except when idling, or stop and go traffic. The one time they did my friend was following me behind my truck in my car. Basically sitting in the draft going 10 miles an hour up a 18 percent grade (yeah my truck is slow). He called me and said your temp guage reads 220 what do I do. I said pass me, and it dropped below 200 in 30 seconds.</p>

That fans aren't just for idling...

Oh.

Well to be honest, if you have a/c, and a big intercooler, and a nice radiator, and no hood vents, crapy stock ducting, he's absolutely correct. With my setup I was able to mostly* control temps with all the above by having awesome fans. I had probably 5/10 ducting at the time. Biggest problem was the huge IC just completely blocked airflow to the radiator.

But now I moved the a/c condenser, swung the intercooler out of the way so the radiator gets clean air, and did the best ducting job BY FAR I've ever done, it's 10/10. Now I have sheet metal sealing every hole in the bumper, air can ONLY go through the radiator. And now the car runs thermostat temp all the time when driving.

I personally gave up on the idea of having 3 large stacked heat exchangers in the front and trying to make that work perfectly. Now it's just intercooler and radiator up front and that makes a huge difference.