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Discussion Starter #1 (Edited)
I took out the mechanical fan this past weekend. This is a common mod on e36 and e46 M3's, supposedly worth 8hp on a dyno. The electric pusher fan is still there, for idling in traffic. I may get an additional electric fan before the weather warms up, if i feel any difference in power. Initial impressions are minimal, I pretty much i don't notice any change, not that I could feel 3-4 hp if it actually gained anything. At idle, the engine seems to rev a bit freer, but it could be the lack of fan noise...
What can I say, the weather was bad and I was bored, this is a 3 minute mod! (it is surprising how much noise the fan made, now that it's gone!)
Mike
 

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Ok, I guess you are now going to remove the power steering as well! Have your thought about the Evosport power pullies?

Mark
 

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Mike:

Do you think the standard electric fan will be enough in July in bumper to bumper traffic? I think "mr bock" has a full electric fan setup. Let me know how this does in some spirited driving runs.
 

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mottati said:
I took out the mechanical fan this past weekend. This is a common mod on e36 and e46 M3's, supposedly worth 8hp on a dyno. The electric pusher fan is still there, for idling in traffic. I may get an additional electric fan before the weather warms up, if i feel any difference in power. Initial impressions are minimal, I pretty much i don't notice any change, not that I could feel 3-4 hp if it actually gained anything. At idle, the engine seems to rev a bit freer, but it could be the lack of fan noise...
What can I say, the weather was bad and I was bored, this is a 3 minute mod! (it is surprising how much noise the fan made, now that it's gone!)
Mike
If you happen to be able to plan in a dyno of the car with and without the fan that would be quite interesting.
 

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There is nothing wrong with removing the clutch based fan, I do it on all of the Supercharged conversions and have considered the same on NA applications as well. However, I would highly recomend replacing it with a good electric fan. If the motor were to overheat it will become a very expensive service call.

With regards to the pusher fan that you spoke of; it is the aux. AC fan and is not designed to cool the radiator.......Its primary purpose is to cool the condensor core for more efficient AC operation in the exteme heat.

Take care,

Shadowman
 

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My fan has been out for a couple summers now and no problems, but 90+ degree days are uncommon where I live. I weighed the fan once, but forgot the reading. Maybe about 6 pounds...

edit: it's 4 pounds.

:cheers:
 

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bayerischemotor said:
How did you remove it? You mentioned a 3minute method?

I'm not so intrested in the couple of horse powers, but if it makes the car idling and running quieter that's enough for me.
Removing the fan is super easy... put a big wrench on the nut (where fan meets the engine) and give a quick smack to the wrench with a hammer. Caution!!! REVERSE THREADS!!!! Spin the nut free and out comes the whole fan. When I first did mine, I drove the beast for a few miles to see how it felt. The only thing I noticed is that the rpms stayed higher between shifts. Due to less inertia/drag??? My temp was going up some while sitting at stop lights, so I added the electric fan (pulling air throught the radiator). Something different?, minor enhancement?

LOL
 

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Discussion Starter #9 (Edited)
Mr Bock has it right. Big wrench (i used a crescent), wack towards the right it spins right off. Nothing else needs to be removed too get it out.

If i get on a dyno anytime again soon, ill try both with and without.

MAH: i already have the pulleys!

I will either re-install it or go the electric route, before the weather gets warm. Today, with plenty of driving around town in traffic, coolant temp never went beyond 12 oclock (i know that is meaningless), at low load cruise it's at my normal 'wintertime position' of about 11 oclock. Oil temp never over 200, usually around 180. So i'd say it's ok for 50F weather. The aux did kick on a couple of times at prolonged traffic lights etc. No changes under hard acceleration either (as far as temp), but again, it's cool outside.

Another plus is no worries about the self destructing OE fan/clutch assembly. I figure if that were to go, in addition to a rad and hoses, i'd be shopping for new cai tubes!
Mike
 

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mr bock,

what type of project (approx. time and expense) is putting in an electric fan? Did you do this yourself?

Thanks.

mr_bock said:
Removing the fan is super easy... put a big wrench on the nut (where fan meets the engine) and give a quick smack to the wrench with a hammer. Caution!!! REVERSE THREADS!!!! Spin the nut free and out comes the whole fan. When I first did mine, I drove the beast for a few miles to see how it felt. The only thing I noticed is that the rpms stayed higher between shifts. Due to less inertia/drag??? My temp was going up some while sitting at stop lights, so I added the electric fan (pulling air throught the radiator). Something different?, minor enhancement?

LOL
 

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Discussion Starter #11
2003 M5!!! said:
mr bock,

what type of project (approx. time and expense) is putting in an electric fan? Did you do this yourself?

Thanks.
2003, i think mr bock did a write up a while back. Additionally, Discovery automotive has a really nice set up that they use for their S/C cars, that you could check out. I'm going to do some searches on Summit racing and Jegs websites for fans. It should be a pretty straightforward project.
Mike
 

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Thanks. I will look for bock's write up. Take care.

mottati said:
2003, i think mr bock did a write up a while back. Additionally, Discovery automotive has a really nice set up that they use for their S/C cars, that you could check out. I'm going to do some searches on Summit racing and Jegs websites for fans. It should be a pretty straightforward project.
Mike
 

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I have used Spal fans in the past with much success. I use two pushers on my Fluidyne rad in my Porsche with low amp draw.
 

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Discussion Starter #15
ray540inyc said:
theres a guy on the roadfly board that has a dual fan set up in his 540 too. i'll try to get the pix from him in the install. im sure its probably close enough for the m5.

ray
I'd be curious to see that. It doesnt seem like there's enough room for two fans, but maybe. Most 16" fans on sites like summit or jegs will pull about 2350cfm for about $200, not including thermostat, wiring etc.
Mike
 

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For a quick three minute mod yes this is good( I'll admit I've already done it on other cars).
With the underdrive pulley system the other equipment, A/C,P/S, Alt all could have reductions with it. Isn't a clutchfan to slip under hard excellerations?
 

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Discussion Starter #17 (Edited)
6spd said:
For a quick three minute mod yes this is good( I'll admit I've already done it on other cars).
With the underdrive pulley system the other equipment, A/C,P/S, Alt all could have reductions with it. Isn't a clutchfan to slip under hard excellerations?
Sure it does slip, but it certainly has quite a bit of drag, even when it's cold. Besides, i already have the underdrive pullies.
I remember the old GM clutch fans were real loose (especially as they got old). After shutting down my 67 pontiac gto, i could get out, open the hood and the fan would still be moving! (even then, i removed it and installed an electric fan!)
Mike
 

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10-4 chief, pulleys are good, stock fans are loud.
I'd like to see how the fans are mounted on the 540 rad.
 

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shadowman said:
There is nothing wrong with removing the clutch based fan, I do it on all of the Supercharged conversions and have considered the same on NA applications as well. However, I would highly recomend replacing it with a good electric fan. If the motor were to overheat it will become a very expensive service call.

With regards to the pusher fan that you spoke of; it is the aux. AC fan and is not designed to cool the radiator.......Its primary purpose is to cool the condensor core for more efficient AC operation in the exteme heat.
Guys, I am not a fan of this mod (pun intended) so I will take a bit of a 'show me' stance.

How much energy does the mechanical fan REALLY take? Not 'I heard' or 'probably'... any hard data? If it really took 8HP can you imagine what an 8HP electric motor would do to than fan????

Look at the work being done- 11 inclined plastic blades spinning at 6000 rpm- could a 2 HP motor do this? 3? Whatever the power to accomplish that speed IS the power draw on the engine. (Minus viscous heat generation in the coupling..)

and what is the potential cost of this mod? My guess is that you will loose cooling performance, no matter what the damped temperature needle tells you- a continuous flow of air that keeps the temp low is better than a feedback system that responds to increased temps. What of the fan fails? or a wire fails? or a sensor fails? Do you loose AC performance? How much MORE does the AC pusher fan run because it has no underlying airflow from the mech fan?

This mechanical system is failsafe (well, nearly so) and is there for a reason.

And when you need the cooling and the electric fan is running, the power IS coming from the engine.

Obstinately yours,

Ard

PS I guess living where it is 90+ almost every day in the summer (and a bunch over 100) gets you this way...
 

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Discussion Starter #20 (Edited)
i understand what you're saying. Typically, you really only need the fan at idle, in traffic and "low air flow" situations. At speed, on the highway, there's plenty of airflow thru the rad. Hence the fan clutch (which always putting some drag on the engine). That's not much of a defense, but what the heck it was a boring rainy day, and i felt like messing around with the car.
I agree the ac pusher fan is probably not enough for hot weather, and the coolant temp gauge is not enough to trust (but i do think oil temp is a pretty reliable indicator, so far not above 200F). I'll either add an electric fan, that would probably rarely run, or slap the oe fan back in place...
Mike

ard said:
Guys, I am not a fan of this mod (pun intended) so I will take a bit of a 'show me' stance.

My guess is that you will loose cooling performance, no matter what the damped temperature needle tells you- a continuous flow of air that keeps the temp low is better than a feedback system that responds to increased temps. What of the fan fails? or a wire fails? or a sensor fails? Do you loose AC performance? How much MORE does the AC pusher fan run because it has no underlying airflow from the mech fan?

This mechanical system is failsafe (well, nearly so) and is there for a reason.

And when you need the cooling and the electric fan is running, the power IS coming from the engine.

Obstinately yours,

Ard

PS I guess living where it is 90+ almost every day in the summer (and a bunch over 100) gets you this way...
 
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