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Electric Radiator Fan


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#1 limby2000

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Posted 01 January 2020 - 06:58 PM

Right, i know this is a very polarising subject, almost as bad as the coil springs v rubber dougnuts. However my build is finished and i,m toying with the idea of replacing the driven fan with a thermo controlled fan. Has anyone done this,the trouble is my car can be stuck in traffic for an hour and still just goes over normal, it takes forever to warm up. I have fitted an early 90,s cooper wing mounted fan inside the wing (on a switch), but have never come close to using. I do have the smaller pulley as i have the cooper head with clearance issues. Thanks for reading this long intro. Thoughts please.

#2 limby2000

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Posted 01 January 2020 - 07:00 PM

Forgot to say, i have a new 88 degree thermostat, new standard rad.

#3 MiddletoM

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Posted 01 January 2020 - 07:29 PM

edit - didnt read the post properly


Edited by MiddletoM, 01 January 2020 - 07:30 PM.


#4 unburntfuelinthemorning

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Posted 01 January 2020 - 08:54 PM

I think the main issue is that with the side mounted radiator arrangement you need a fan to ensure some airflow through the radiator - even when the car is in forward motion - and a lot of electric fans are only really designed to be used for short periods and not to be on constantly.  If the electric motor was suitable for constant running then it would work but I don't think you'd gain much from it.  The coolant in the radiator remains cold until the thermostat opens so having no fan turning would make little difference to warm up speed.  On conventional layouts in other cars with a front mounted radiator and a longitudinally mounted engine it would be advantageous to warm up speed to remove the fan as the fan is sucking cold air though the radiator and then blowing it over the engine block as the engine is trying to warm up.

 



#5 Cooperman

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Posted 01 January 2020 - 08:57 PM

The Mini needs a fan to be on virtually all the time.

An electric fan could be made to work OK, but it would need to be capable of moving the same volume of air as a mechanical belt-driven fan and have a duty cycle of 100%. 

Some after-market auxiliary fans will not shift the necessary volume, not will they accept being on all the time.

A thermo-switch is OK for auxiliary fans, but for an electric fan as the only fan you might as well just wire it in permanently 'on'. That leads to the question of what you would hope to achieve with just an electric fan.

I have an electric auxiliary fan in addition to a 6-blade 'Export' fan on my 1964 Cooper 'S', but I would not like to have it as the only method of cooling.



#6 nicklouse

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Posted 01 January 2020 - 09:24 PM

I the main issue you have is the air in the wheel arch is a high pressure area and it is not just the volume of air you need to shift to do the cooling but also the pressure to overcome the pressure under the wing or you get no flow. So no cooling. 
 

ever wondered why Rover fitted to extra electric fan but kept the engine driven one?



#7 Compdoc

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Posted 02 January 2020 - 11:50 AM

I the main issue you have is the air in the wheel arch is a high pressure area and it is not just the volume of air you need to shift to do the cooling but also the pressure to overcome the pressure under the wing or you get no flow. So no cooling. 
 

ever wondered why Rover fitted to extra electric fan but kept the engine driven one?

Does this mean that some vents in the "A" panels would improve the flow even when using the standard fan?



#8 cooperd70

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Posted 02 January 2020 - 12:28 PM

Limby2000

Check out the below two posts. They may be of help.

http://www.theminifo...ric-fan-on-mk1/

http://www.theminifo...their-web-site/

I have fitted a thermo switched fan kit from Minispares and as per the instructions with the kit removed the mech fan. Others here have advised against removing the mech fan.

My car is for dry/sunny days only and after having the kit fitted for just under a year I will be refitting the mech fan this spring before the car has further use. Without the mech fan the thermo fan just keeps cutting in too often during the summer. As others have mentioned to me keeping the mech fan does two things:

i) the thermo fan will only cut in when your stuck in heavy traffic and your car gets v hot.

ii) if the thermo fan were to ever break down you have the mech fan working as it has always done allowing you to continue on your journey.

There is no issue with leaving the mech fan off, but I am choosing to pop it back on as a safeguard.

I had no need to modify any bodywork for this addition. My car is a 1990, but not a Cooper so it doesn't have the aux fan fitted under the wheel arch. The kit I fitted sits in-between the rad and the innerwing.

DC.

Edited by cooperd70, 02 January 2020 - 12:31 PM.


#9 unburntfuelinthemorning

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Posted 02 January 2020 - 03:17 PM

Does this mean that some vents in the "A" panels would improve the flow even when using the standard fan?

 

If you increase the pressure differential across the radiator it will improve airflow through the radiator. 

 

The early Minis with the radiator shroud were better in this regard as the air coming in the front grille only got to the fan side of the radiator.  If you reduce the air pressure in the wheel arch it will help radiator airflow but only if a shroud is fitted between the radiator and inner wing. 

 

In theory if the engine bay was sealed so air coming in the grille could only flow out via the radiator and inner wing and the wheel arch was at a lower pressure than the engine bay then it probably would be possible to run without a fan for all but low speed work.



#10 Moke Spider

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Posted 02 January 2020 - 05:32 PM

For low sped and being caught in traffic, an electric fan may help, otherwise, it's only an obstruction to Air Flow.

 

As Nick and Unburnt mentioned, there's very little natural pressure drop, between the engine bay and the wheel arch. With little pressure drop, there's nothing to move any Air through the Radiator, so the fan on a Mini is 'working' all the time.

 

The stock fans on a Mini take between 3 - 5 HP to spin at normal road speeds and that's more or less proportional to the volume of Air these fans move. The best Electric Fan that I've even found is only 0.36 kW or 0.27 HP, so there's no commercial fan available that can effectively replace the mechanically driven fan on a Mini. Further, fitting an Electric Fan as well as retaining the mechanically driven one, when driving at any normal and higher speeds would only obstruct air flow.

 

I feel better benefits could be had from fitting a smaller pulley on the Water Pump and using the first stage of the Choke (Fast Idle only) is more effective overall.



#11 limby2000

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Posted 04 January 2020 - 12:30 AM

I already have the smaller pulley, so is spinning the fan/water pump at faster rate anyway, which may be the cause of my exceptionally lower average temperature. Does anyone the revolution difference between the 2x different sized pulleys?.

#12 limby2000

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Posted 05 January 2020 - 08:34 PM

Thanks for all your views, i will be keeping the pump fan, better safe than sorry, although i will move to the bigger fan pulley.

#13 Cooperman

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Posted 05 January 2020 - 09:10 PM

Thanks for all your views, i will be keeping the pump fan, better safe than sorry, although i will move to the bigger fan pulley.

 

Just to clarify, a bigger fan pulley will slow the fan rotation speed and thus shift less air through the radiator.






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