Electric fan conversion - how much, what's involved?

[Spion]

I've seen them for 30-ish quid (Pacet and other makes). What's involved in fitting one?

[zimmer-320i]

yer id like to know to, bhp gains of 0.01 dont you know

[Spion]

yer id like to know to, bhp gains of 0.01 dont you know

That's not what I'm after. My touring has gone thru two viscous fan couplings in less than 2 years

[zimmer-320i]

?? yer i said id like to know too!! 2 fans in 2 years!!! you not buying gen bmw parts???

well from diffrent cars i know you obisly need the fan id say a draw fan is better than a blower but not sure on the bmw, then you need a electrical thermostat with is easy to get hold of and then the wiring and if your doing it properly wire it in to the fuse box but id just hide,tuck the wires away and 15amp fuse the live to the stat much easier, not the right way but easier lol

[Mikey_Boy]

Hello there,

I am looking at doing this on my 325 right now. Despite popular belief, viscous fans do sap quite a bit of power and also add a lot to the noise radiated from the engine and also use 70's tech for cooling (not optimal). You should see about 3 - 5 hp throughout the rev range from ditching the fan plus quicker warm up. BMW do a switch that screws into the rad that switches at either 91°C or 99°C (see first linky) and the wiring should go through a relay (see second linky) either through the fuse box or somewhere tucked out of the way

Pacet, Spal and Kenlowe do slim fit kits - I am looking at an 11 inch fan - best solution for the BMW is a blower fitted between the grill and rad as the clearance between the engne and rad is tight and the last thign you need is the enigne smashing into the fan under braking - cold smooth airflow is what matters to cool the engine, not the location of the fan...

Linkys:

http://www.realoem.com/bmw/showparts.do ... g=17&fg=05

http://spalusa.com/fans/automated/tech_ ... -195FH.pdf

Hope this helps!

Cheers,
Mikey_Boy

[Spion]

That looks v useful. Ta, mate

[mrLEE30]

Despite popular belief, viscous fans do sap quite a bit of power

the power you save removing the fan is consumed by the alternator to run the electric fan.

about 3 - 5 hp throughout the rev range

my god, then perhaps you can explain what happens once the air hitting the fan is travelling faster then the fan itself i.e above 20-30mph .... would it not speed up the viscous fan and add power to the engine?

plus quicker warm up

surely the thermostat controls the engine temp not the fan

the ONLY advantage to an electric fan is you can control the temp it switches on more accurately...but again the temp of the engine is controlled by the thermostat not the fan.

mrlee

[DanThe]

The only benefit of an electric fan is more space and less noise

[Mikey_Boy]

No. no and no!!!

(By the way - before I start this reply I should point out that I am an ex-F1 engineer and worked for Cosworth developing engines for 6 years....)

Additional electrical load will not sap power- amperage is regulated by the alternator to a fixed value and there is plenty of safety designed into the alternator in terkms of capacity to protect for such things as Air Con, lights, electric seats, sunroofs etc etc - total power loss for an alternator I can guarantee is LESS than a viscous fan (how many viscous fans do you see on moderns cars????)

Airspeed though a radiator is around 6 - 10 times LESS than the speed of the vehicle - rads create an enormous amount of drag and need to to get the air moving slow enough over the fins to rip the heat from the water passing through it - so the air speed through the radiator is very low indeed and designed that way - if the air speed was too high the air wouldn't go through the rad just stall and go around it (any fluid or air flow takes the path of least resistance...)

Thermostat does control the warm up but ALL mechanical stats leak as they get up to temperature and so a consistent volume of water gets through the rad as the engine gets up to temperature and is cooled by the viscous fan - this slows the overall warm up time - electric stats were invented to control the warm up better (for emissions and heater performance) and also to control power - max fuel economy happens at a higher water temp (about 93 degrees) than max power (about 72 degrees) so this in more moderns cars is controlled by the engine management to 'optimise' for all that extra weight we have to lug around!

Considering that a viscous fan can add about 2 - 3 dBA of mechanical noise, that gives you a bit to play with on trackdays as well.....

There are quite a few advantages to even the most primitive of electic fans - fair play to BMW to getting their viscous fan right with the E30 - it's pretty good but things have moved on in the last 20 years or so!!

[Mikey_Boy]

One final thought before logging off referring to 'the power you save removing the fan is consumed by the alternator to run the electric fan' issue:

Current draw of an 11 inch electric is about 7.5 amps

Power (Watts) = Voltage x Amps

Voltage is about 13.5 V with the alternator charging so...

Power (W) = 13.5 x 7.5 = 101.25 Watts

Remember that 1 kW (1000 Watts) = 1.358PS = 1.340hp

Therefore additional power loss of the electric fan when it's running is..... 0.136 hp.

[mrLEE30]

i agree an electric fan will not draw much power and will have no real noticable effect, but i dont belive it takes 3-5hp to turn the viscous fan, once the engine speed overtakes the speed of the fan the clutch stops it dragging on the engine...

[Mikey_Boy]

Agree on all counts - it's not the end of the world but having measured it on a few dyno's in the past - it's surprising...

A message for Spion - as I have just removed my viscous fan (am being stubborn and getting the electric one on for sure!) then PM me with an address and I will post you mine if you need one.....

[mrLEE30]

how many viscous fans do you see on moderns cars????)

the two biggest manufacturers of cars - Toyota and GMC still employ viscous fans one their current models

actually only really having a laugh , I do agree an electric fan is better then a viscous in certain situations.

must have been a laugh working for Cosworth F1, did you travel or were you based in UK?

mrlee

[Mikey_Boy]

Yes Toyota do don't they?? But then Japan gets a touch hotter than most places and having been over there in the height of summer it gets pretty sticky too so they need all the cooling they can get......!

And as for GMC - Ahem.........!!!

Some of my best career years with Cosworth - was an office based chap whilst I was there, glued to my drawing board, computer, test car or dyno cell!! Did the trackside thing with Ferrari some years after leaving Cosworth - great fun but really exhausting and no time for driving any more....

So - Messing around with E30's, doing trackdays and the Nurburgring is just as much fun!

[mrLEE30]

Yep GMC' Tahoe and Trailblazer and Dodge Durangos and Ford Explorers/Expidition Lexus LX470...sorry couldn't resist..

I tinker a bit over here in Bahrain but mainly on Caterhams/Chevy Luminas demonstration cars at the Bahrain Circuit...also do some track instruction which i find much more entertaining

and Japan is not hot, you should try it here.. taken in my old Prado (cooled by Viscous assisted by 2 electric fans

take it easy mate!!

mrlee

[DanThe]

Y

I would collapse then shrivel up in that heat,,,,

[E30BeemerLad]

the fan on the Soarer is a strange configuration.

It is turned by hydraulics/ oil. There's a pump on the front of the engine which is operated by the serpentine belt, this puts oil through the fan mechanism and turns it, but get this, the fan has it's own radiator to cool the oil!

with the rad removed, showing the monster fan

here's the little cooler for the fan, revealed after her indoors managed a spectacular 4 wheel drift into a large signpost

[Mikey_Boy]

Wow - 50°C...............!! That IS toasty!! Nastiest sign off test for me when testing cooling systems was Tokyo city test in summer - not quite 50°C though....!

Looking at the BMW parts lists (being a geek!) I did find that there were 'tropical' spec radiators out there if things are starting to get a bit steamy... From my limited experience with E30's I am led to believe that gearbox oil cooling is the weak link in the chain???

The Japanese really do know how to do cooling and their air con is always the best by a long way...

Only saw Bahrain in March / April time when it wasn't too hot... Great stuff though mrLEE that you get out on track and show folks how it's done - I wish I had that much talent!

Great thread gents - learned a lot!!!

[mrLEE30]

Great stuff though mrLEE that you get out on track and show folks how it's done - I wish I had that much talent!

may be pushing it a bit to say i show em how its done!!!

come do a lap with me in a V8 Holden Commedore - sorry about the angle!!!



mrlee

[tha_lick]

Electric fan is piss easy i think. iv got the setup on my 325i, very effective but once the plug came undone and disconnected the fan, but i suppose when a viscous fan goes its a lot more hassle than plugging it in again. . .

[FlappySocks]

Additional electrical load will not sap power- amperage is regulated by the alternator to a fixed value

Don't think so. The more electricity you pull, the harder it becomes to turn the alternator.

I can guarantee is LESS than a viscous fan (how many viscous fans do you see on moderns cars????)

Probably.

Belt driven:
Pro: More efficient when needed.
Con: Runs all the time which is wasteful, especially when the engine is cold.

Electric:
Pro: Less efficient when running
Con: Runs only when needed.