advice on converting from mechanical to electrical fan

[S14]

Are you just saying this, or have you tested this theory in depth by logging temps? Did the OP disclose his location as Phoenix? Guess I didn't see it. As well, if the AUX fan alone isn't sufficient, neither would the SPAL fan be.

I'm just going off what you said. You said it was enough, and I'm giving you a data point that it is not in some areas of the country. My testing is this: removed the fan clutch and the car overheated while at a steady state of 70mph on the freeway. Put the fan clutch back in and it stopped overheating.

I don't wholey disagree with your second statement. some E46 non M3 cars came with just an electric puller fan, and the Z4 M came with a pretty big electric puller fan, so it can be done. But, depending on the location, running just the Aux fan could be bad for the motor. I switched to a mishimoto fan and it was also not sufficient. I've since reverted back to both stock fans and my overheating has almost completely subsided.

[S14]

OP - part of my engine rebuild includes ditching the clutch fan and auxiliary fan in favour of a mishimoto puller fan (and mounting kit) which will run off the auxiliary fan controller. It does get hot where I am; ~42c at the peak of summer, usually around the mid-high 30's.

Water pump and thermostat are brand new, radiator has been flushed and has zero blockages. Will be filled with the correct oe coolant/distilled water mixture and bled correctly once everything is back in the bay.

I bought the mishimoto fan with the kit and ran it off the aux fan controller. Phoenix gets up to 42c regularly and it couldn't keep up at all! My car was custom dyno tuned on 93 though, and running 91 in the heat is a contributor. I recently was experiencing overheating on track with 91 octane. Once I put in a 1/2 tank of 100 octane the overheating was far less frequent. My car needs the timming pulled back a bit, but even in normal sub 3k diving, just the mishimoto fan was incapable of keeping the car cool with or without the AC on.

[eacmen]

I'd ditch the OEM controller. I'm pretty sure it doesn't run at full tilt most of the time. If you delete the mech fan and replace the aux fan, you want to run the fan at full speed as much as possible.

I would install a temp switch in the upper radiator hose to trigger the fan. When the fan is on, its comes on 100% which is what you need in hotter climates.

FYI...for those that don't care about noise, I just installed a 30102120. It is loud as hell but its also the highest output fan that SPAL sells. The motor is pretty big so its gonna be a challenge to make it fit. Not sure which model SPAL fan I had before but this fan moves WAY more air.

Concur with this. The oem aux controller does not seem to drive the puller at full speed.

Dedicated fan controller and a shroud like the N15 should be able to generate enough air flow over the rad.

For street cars that retain the A/C and use it while stopped I would still recommend keeping the aux pusher fan.


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[bigjae46]

I'd ditch the OEM controller. I'm pretty sure it doesn't run at full tilt most of the time. If you delete the mech fan and replace the aux fan, you want to run the fan at full speed as much as possible.

I would install a temp switch in the upper radiator hose to trigger the fan. When the fan is on, its comes on 100% which is what you need in hotter climates.

FYI...for those that don't care about noise, I just installed a 30102120. It is loud as hell but its also the highest output fan that SPAL sells. The motor is pretty big so its gonna be a challenge to make it fit. Not sure which model SPAL fan I had before but this fan moves WAY more air.

[tnord]

So my reasoning for switching is as follows: Im at 90k miles and was either going to replace the mechanical clutch, to prevent fan blade explosion, or switch to an electrical fan. Read up a bit and found that with a spal fan that pulls above 2000cfm, no one has had any issues with cooling in hot climates or track days. The larger fans must be mounted offset to avoid hitting the clutch fan nut, so keeping the original shroud isn't an option, which is why im looking for a mounting option. My aux fan failed at 7 years and 40k miles. Its runs approx $600 and my current one has already passed the 7year and 40k mile point. Why would I want to keep an extremely expensive failure point, when I can replace the potential bomb and the expensive aux fan at the same time with a fan that effectively does both jobs better?

I work on my car a fair bit, so I would want a mounting solution that is easy to remove. Advice on this point?

Im in south fl currently, so Ive been paying particular attention to the others who are running these setups in hotter climates. I also want to be able to do track days and autox, but I dont think they put as much strain on the cooling system as idling in 100F while blasting the a/c.

Ive read that running just a 1400cfm puller fan, is not enough in the hotter climates. However, no one has told me that they run just the aux fan consistently in hotter climates with success.

Im open to giving just the aux fan a try for science and if it does cool the car well enough to keep it within normal temps, I might just do the mechanical delete for now until the aux fan dies and then replace it with the spal puller.

dl.M3 and rbg, thanks for the info!! leaning me towards trying just the aux fan

I went through roughly this same process when I was replacing the cooling system a couple years ago. I ended up just ditching the mechanical fan, and I will say that the aux fan seems to run more frequently now.

I'm in Kansas City, so not exactly Phoenix, but not exactly Chicago either. It gets plenty hot here. I haven't ever seen temperatures get to the point where I need to shut the car down, but I was tooling around a couple weeks ago on a near 100deg day and I saw the oil temps start to creep above 210 (normal), same with water temps. As long as I kept moving everything was fine, but I was cautious enough that I turned the AC off and opened the windows.

Before you ask, I have a <10k mile OE radiator, OE pump, OE coolant, all new hoses belts, AC condenser blown out, etc.

As long as the car is moving, you don't need any fans, and I would suggest they actually diminish cooling. At least on my miata SCCA car, I and everyone else took them off. I'm still undecided on what the best setup is. I like removing a failure point, cleaner engine bay, less drag, all of those things. But I don't like that the aux fan seems to be running more often. Money no object for a street car setup would be a big fat aluminum radiator with electric fan.

[WOLFN8TR]

I'm currently running the Spal 2082 using the N15 fan mounts with the Aux Fan in place. I have a PWM unit running the Spal Fan. I originally ran the Mishimoto fan mounted inside the OE fan shroud. This did work but I experienced temperature creep on HOT days over 115 degrees. So it really depends on your climate, our desert heat is brutal so the two fan setup is a must.

Here is some info from the old M3Forum about Spal Fans. This was from a Spal Technician when asked what the best Spal fan to use for our application.

Spal 2021, 2049,2082

At static pressure mmH2O = CFM (which is what you look for in a fan because the total output is always at measured at 0 which is not really relevant in this case because this being installed in car radiator is pretty much always subjected to static pressure unless you have the car parked and not moving at all. Typically the higher amp rating the more CFM's as well.

The higher mmH20 and CFM the better.

Spal Fans:

20 mmH2O

2049: 389 cfm at 20.6 amps
2021: 702 cfm at 19.5 amps
2082: 991 cfm at 24 amps

25 mmH20

2049: 0 cfm’s at 17.7 amps
2021: 378 cfm’s at 19.5 amps
2082: 596 cfm’s at 23.6 amps

30 mmH2O

2049: 0 cfm’s at 16.5 amps
2021: 0 cfm’s at 19.2 amps
2082: 384 cfm’s at 23.8 amps

[Syfon]

The mishimoto fan is only 1800cfm and mounts the same way the spal fan would. Depending on the mount you get, the price for a 2024 or 2080 spal fan with a nice mount should be nearly the same as the mishimoto and youd get more cfm. Let us know what you end up going with and how your setup runs when you get it done!!

Yeah 1850cfm according to their website. I have their mount too.

Yep! Once everything is back in and running i'll report back with a host of data in my thread

[sapote]

So my reasoning for switching is as follows: Im at 90k miles and was either going to replace the mechanical clutch, to prevent fan blade explosion,

I can understand this is an expensive damage if it exploded. As said my other 323iT 180K miles still with original. I think one can check the condition of the clutch fan as a maintenance schedule to avoid it locking up at high rpm and exploded.

[sapote]

Ill just say the clutch fan definitely has wear and tear, with potential catastrophe.

As for temps, I've ran no clutch fan the entire summer, never had a problem even with A/C.

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The clutch fan use viscous oil (like a torque converter in auto tranny) and so almost no wear and tear. My 2000 323iT 180K miles still with original stock fan. My M3 80K still with stock fan.

"I've ran no clutch fan the entire summer, never had a problem even with A/C."
It will do ok with temperature, but it will have shorter life as compare to stock set up. Wait and see.

[dl.m3]

I really think a shroud has a lot to do with the effectiveness of the electric fan, more so than raw CFM. Both the OEM aux and clutch fans have shrouds that channel air through the blades.

I'm not aware of any existing electric fan solutions that come with a shroud that fits our rad. Def not Spal/Morimoto

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[Rich022]

I went with the highest cfm SPAL makes that is still considered "low profile"-- if memory serves me, it's 16" /straight blade and is rated for ~1860 cfm and is around 2.7" in depth-- I could not find a published number for the mishimoto fan. However, that is a slick, hassle-free fan install and I have a practically brand new one, still in the box if you would like to purchase.
The conditions that I exhibited rising coolant temps were: AUX fan delete: ambient temps in the 90s (Houston) A/C ON or OFF while in traffic/standstill. Coolant temps would creep up to 210 F when at that point I switched the heater on which quickly lowered coolant temps. I believe i posted my scenario a month or so ago... SPAL fan was hooked up via my switch below. setup and I also tried using the AUX controller-both conditions resulted in potential overheating conditions..

Currently running the SPAL fan off of a separate relay that I have in the drug bin with an in-line fuse setup-all purchased thru Summit-- it's the only safe reliable way to run high amp draw. Soldering is a necessary evil also. The "on/off switch" for the fan I went with a temperature switch JB welded between radiator fins just above and to the side of the lower radiator hose. I believe the switch setpoint is 185F/ON and 165F/OFF (radiator temp) bought on ebay. This switch parameter has worked very well for me. The OBD coolant temps never rise above 195F while in traffic etc. again, in combo with the AUX fan.
When I experimented with the SPAL fan only, I did hook up the AUX controller as it's already relay protected and is in close proximity to the fan, so it's a straight 2 wire connection directly to the SPAL, but ultimately had to go back to running SPAL + AUX.

[zing]

OP - part of my engine rebuild includes ditching the clutch fan and auxiliary fan in favour of a mishimoto puller fan which will run off the auxiliary fan controller. It does get hot where I am; ~42c at the peak of summer, usually around the mid-high 30's.

Water pump and thermostat are brand new, radiator has been flushed and has zero blockages. Will be filled with the correct oe coolant/distilled water mixture and bled correctly once everything is back in the bay.

The mishimoto fan is only 1800cfm and mounts the same way the spal fan would. Depending on the mount you get, the price for a 2024 or 2080 spal fan with a nice mount should be nearly the same as the mishimoto and youd get more cfm. Let us know what you end up going with and how your setup runs when you get it done!!

[zing]

Fan debate almost like 'what oil to use' debate. To answer the original question where to mount the controller, the N15 setup would be easiest as running wiring for the aux controller to the drug bin would be a big hassle that's not necessary. and running the aux fan without a clutch fan will have little impact on overall aux fan life--you would be surprised how often it runs anyway. There's a thread on the % on vs. temp/speed that the aux fan is on. If going SPAL fan, spend the money on a more permanent setup like the N15 vs. those zip tie solutions. No familar with the Condor setup. Also buy the rubber gasket for the fan that rests on the radiator.

For me, I was unable to keep coolant temps under control running SPAL fan only and had to reinstall the AUX fan. What a pain that was....

Rich, what cfm was your spal fan? what conditions were causing your coolant temp to go above normal levels?

Since you are currently running both, did you use another controller for the spal fan or the relay kit?

[zing]

The SPAL is not really necessary to be honest. I've been running with just the AUX fan and no mechanical fan for a couple of months through the Summer. We just had a 115 degree day here in SoCal, and my highest coolant temp was 210f while climbing the 15 fwy for about 10 minutes straight. Once I hit flat road, it immediately dropped back to 200f, and sat idling afterward at 194f. That's literally the highest temp I'll probably ever see in this car and though it got a little on the warm side during the ascent, it was never at risk of damage and within normal operating range.

The mechanical fan seems to be there for redundancy as far as I can tell...and probably does create a cooler environment faster, but if you have a properly bled cooling system with fresh coolant and a clean radiator...you should be fine in almost any climate with just the AUX fan.

I personally see no reason to remove the AUX fan for a puller fan...I've actually heard of temps running higher this way.

Thank you! This is super valuable info. Anyone happen to know the cfm capabilities of the mechanical and oem pusher fans? Anyone else running just the aux fan for autox or in ridiculously hot climates?

Since my aux fan already failed on me once, I dont have a problem replacing it in favor of the puller fan. Ive yet to hear of any issues with a 2040cfm puller

[Rich022]

Fan debate almost like 'what oil to use' debate. To answer the original question where to mount the controller, the N15 setup would be easiest as running wiring for the aux controller to the drug bin would be a big hassle that's not necessary. and running the aux fan without a clutch fan will have little impact on overall aux fan life--you would be surprised how often it runs anyway. There's a thread on the % on vs. temp/speed that the aux fan is on. If going SPAL fan, spend the money on a more permanent setup like the N15 vs. those zip tie solutions. No familar with the Condor setup. Also buy the rubber gasket for the fan that rests on the radiator.

For me, I was unable to keep coolant temps under control running SPAL fan only and had to reinstall the AUX fan. What a pain that was....