electric fan conversion

[potman]

hello everybody peeps

i've been told recently that if i remove the fan from my car and fit an electric fan it will release some more power from my car.

has anyone ever done a conversion? how easy is it? what are your views on this claim.

i'm not expecting a huge increase in power but every little helps

[12345kevin]

Will probably give a "little" more power when it's not running, going to be about the same when it is as it puts more strain on the alternator !

[Ziggy]

As above - barely any difference when not running, but less efficient when running...

Plenty of people have done it though - myself included!

[potman]

As above - barely any difference when not running, but less efficient when running...

Plenty of people have done it though - myself included!

how dificult is it to do?

what made you decide to do it?

[Ziggy]

Not 'difficult' at all, but there's various ways of going about it...

You try fitting a viscous fan on the front of an M30 in an E30

[potman]

oh,
i didn't notice your conversion.

[leee111]

you are just looking to do alot of diffin

[potman]

not really, just trying to squeeze all the power i can without doing an engine change just yet.

[Turbo-Brown]

I did it because my old visc fan kept melting and jamming in the radiator

It'll only be running when you're going slowly but it'll run full tilt and do a good job of cooling the engine.

I'd say you should see an overall gain in economy if nothing else, and it makes the cooling system more stable IMO.

[leee111]

what all have you dont to your engine exhaust ect

[leee111]

is the fan not noisy

[Gwynleym10]

RS Turbo fans fit in front of m40/m42/m50 radiators (maybe m20) It mounts easily on a couple rubber airbox mounts.

You can wire it in to just a switch (I used an extra rear window demister one) or have it thermostatically switching on and off. I found that even in summer in central London traffic I only needed to switch it on after at least 30mins of crawling - when guage was just getting above half.

I don't think it will create any noticable power, but your engine should warm up quicker (saving fuel) and I think it will save fuel overall.

BMW are now using more and more electrical anchillaries, fan, water pump, power steering etc etc the believe that it can help with emissions as well as power.

[fuzzy]

ive got twin cosworth electric fans fitted and the speed that the car will go from 3/4 temp to just a 1/4 temp is very impressive, less than 30 seconds in standing traffic on hot sunny days. very efficient imo.

[StuBeeDoo]

RS Turbo fans fit in front of m40/m42/m50 radiators (maybe m20)

Definitely M20 - I've done it. I think the cooling effect could be a bit marginal on a 323i or 325i though.
If I ever get 'round to putting my 2.3 project engine in the Touring, I'll be going for a bigger fan, to be on the safe side.

[Colonel Sanders]

can you have an electric fan an keep the standard one?

[cypriot_boy_2k7]

whats the point in that? aint it meant for removal of the viscous fan?

[fuzzy]

i suppose you could have one in front of the rad as well pushing the air through...

[Brianmoooore]

The standard fan with a viscous coupling works well and is reliable. It's not broke, so don't try to fix it!
An electric fan will be far less reliable than the OE one (something you will only probably find out when the gauge goes into the red in a summer traffic jam), and is inefficient, because it first requires mechanical energy to be turned into electricity (an inefficient process), then requires electricity to be turned back into rotational energy (another inefficient process).

[Gwynleym10]

Brian, so why is BMW moving towards more electrical devices rather than mechanical in the drive for more efficiency? Is it purely down to more advanced alternators?

[harry_p]

US spec e30 m3s use a viscous coupled engine fan and an electric fan on the front of the radiator.

euro spec e30 m3s just use the electric fan in front of the rad.

mine seems to cope perfectly with a long hard run followed by sitting in traffic in the hottest of (rare) uk summer days.

[oze30]

Will probably give a "little" more power when it's not running, going to be about the same when it is as it puts more strain on the alternator !

I don't think so.

A viscous is rotational mass and then is affected by wind resistance causing drag on the water pump.

An alternator won't cause any more drag or resistance to the current setup as it will always have the same resistance (It's not turning anything bigger or more drag).

The stock A/C fan is enough to cool an M30 and M60 so I guess it's good for anything.

Viscous on an M30 will be tough. There is bugger all room in front of the engine even with E30.de mounts and an E28 535 rad (I've tried.. No joy!)

[Brianmoooore]

An alternator won't cause any more drag or resistance to the current setup as it will always have the same resistance (It's not turning anything bigger or more drag).

I think you need to read up on the theory of how alternators work.
Rolling road dynamometers are just big alternators (and heaters).

[Brianmoooore]

Brian, so why is BMW moving towards more electrical devices rather than mechanical in the drive for more efficiency? Is it purely down to more advanced alternators?

Wasn't aware they were, to any great extent. Latest models don't have a mechanical fan?
Electric steering assistance only draws power when there is a steering input, while a hydraulic set up consumes appreciable power all the time, so that one's easy. Easier factory assembly as well.
I've come across electric auxiliary water pumps on BMWs, which presumably stop heat soak when the engine is stopped.

All E30s are fitted with an electric fan, as well as the mechanical one, when they are fitted with aircon., to cool the aircon rad when the engine is idling.

[Gwynleym10]

Looks as if the main water pump is electric. Not sure where I read about the electric fans - but pretty sure I did

http://www.channel4.com/4car/ft/feature/feature/9574/1

http://www.bmw.com/com/en/insights/tech ... rview.html

Oh and you know why I'm questioning about this!

[oze30]

Isnt an alternator just like an electric motor, but working backwards? If so, you turn a motor by the armature and it will produce energy. SO, wouldn't that mean that as it turns, the alternator is always producing power to replenish the battery and hence causing minimal drag whereas the viscous will turn at a rate proportionate to the engine speed according to the oil weight in the viscous? So the faster you go, the faster the fan turns thus pulling in more air (like a plane propellor).

So, going by this, wouldn't that mean that the alternator would be producing less drag than the viscous would at any given rpm?

Is there any mechanical drag on an alternator? Or is it just the bearings and the magnets/wires inside?

[johnl320]

You don't get something for nothing, the more demand put on an alternator the harder it becomes to turn. Taking HP from the engine.
When a viscous fan is disengaged it still spins but thats caused by slight drag in the unit, the power it consumes is negligable.

[oze30]

You don't get something for nothing, the more demand put on an alternator the harder it becomes to turn. Taking HP from the engine.
When a viscous fan is disengaged it still spins but thats caused by slight drag in the unit, the power it consumes is negligable.

So the power consumption of an alternator would be negligible too as the pulley is smaller, thus turning faster??

I still fail to understand how a floating magnet/rotor pruduces drag when more electricity is asked from it. To me it doesn't make sense.

An alternator is like a bike dynamo. you turn it and it produces elec. When you stop or start off, the dynamo needs to rotate therefore the pedals are hard/difficult to turn. Once moving however, the light produced is corresponding to the rpm at the wheel. SO, the faster the wheel spins, the more rpm there is, the brighter the light. Drag on the dynamo remains the same.

That's my understanding of it (in a very basic way.)

[oze30]

Cancel all that. I worked it out! Having a moment here.

[johnl320]

Get in a modern car, sit in it ticking over turn the lights on and look at the rev counter fluctuate. The ecu is adjusting the tickover because of the extra load put on the engine by the alternator.

Drive with everything electrical switched on and you will use more fuel than if everything was off. You can't get energy for nothing.

john

[harry_p]

i'm not sure how to describe whats happening, but sit a car at idle with no extra electrical items on, then turn on the lights, heater, heated rear screen etc and the idle will drop slightly, which to me suggests the engine is having to work slightly harder to run all the electrical devices via the alternator.

[Brianmoooore]

IIRC, ( from the day job) the power consumed by an alternator, in H.P. is roughly the same as it's output in kW.
(Or possibly the other way around).
The drag on an alternator is almost all magnetic, and can't be felt when spinning it slowly.

[robbo86]

back on topic, is therre anything to be gained (i am not looking for power gain) from fitting a kenlowe electric fan to mine and if so what, has anyone done it

[oze30]

I think so as there will be less rotational mass for the engine to spin.

[Brianmoooore]

back on topic, is therre anything to be gained (i am not looking for power gain) from fitting a kenlowe electric fan to mine and if so what, has anyone done it

There is nothing appreciable to be gained, and plenty to lose, when it fails.