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MG MGA - Electric Fan

I have acquired a Kenlowe elecric fan which was mounted with plasic tags pulled through the radiator core fins. I intend to fit this fan on my A but am reluctant to tag it to the rad. core fins as I don't want to damage the fins. Any other more logic way to fit it? I do not have any other mounting fittings for the fan.

Frank
F Camilleri

Frank,

yes platic tags through the rad unsettled me too.

I bought the optional mounting kit, which I thought looked naff so I didn't fit it.

I ended up mounting the fan by drilling two holes in the radiator duct panel which matched two slots on the bottom of the fan. To stabilise it I made an aluminium plate up that bolted to the top of the an and then to the bolts where the bonnet catch goes. Nice and solid. It's not the best work of art, but I plan to tidy it up.

I am away from home for a few days, but I'll post a couple of pictures when I get back.

Good luck,

Grant :-)

G Hudson


Frank,

check www.spal.it , they have a nice fitting kit. Hopefully it will fit the Kenlowe fan...

Siggi
Siggi

Thanks Grant, yes I would love to see your set up, please post some pics as soon as you can,
Siggi thanks for the site, I will check it out right now.

Frank
F Camilleri

Frank
Look up Neil Ferguson's thread (02/November/2009) named :twin radiator fans: (the Davies Craig type).

You will see that they were fixed to the radiator by plastic threaded rods that go through the radiator core near the top and the bottom where there are no fins on the tubes. The outer fixings used extra bolts through the radiator fixing flanges.

I would imagine that they will supply parts of their fan fixing kit that you could use to fit your kenlowe.

Or the pictures on Neils thread may help you to design your own.

Colyn "Tripods"
Colyn Firth

Thank you so much Colyn. Will have a look.

Rgds
Frank
F Camilleri

I've managed to install the Kenlowe fan which I attached to the front of the rad. Since the car is positive earth, I had to reverse the connecting wires to get the fan to turn in its normal direction, i.e., clockwise. It is now pulling air from outside the front grill into the radiator. I don't have any instructions with the fan but I am assuming this is the way it should be fitted to have the desired effect. Does reversing the fan's polarity have any ill-effects on its motor?

Frank
F Camilleri


Frank,

if your blower is pulling air it must be mounted behind the radiator, i.e. engine side.

Siggi
Siggi

I think he meant pulling air through the grille and pushing air through the radiator. Lots of aftermarket fan motors can reverse direction of rotation simply by switching the wires. If you also turn the blade around (for best efficiency) it can then be used as either a pusher or puller.
Barney Gaylord

Barney

I understand that what you were trying to say was that if you change fan rotation direction by swapping leads etc you may also need to turn the blades round to keep the correct blade profile facing the airflow. What the unwary should understand is that merely turning the blades round but keeping the direction of rotation the same does not change a puller into a pusher or vice versa. The air flow past the fan blades will remain the same; just the fan efficiency may be altered, depending on the blade aerodynamic profile.

Steve
Steve Gyles

Well, no. I just stated the short version. If you turn the whole unit around to change from pusher to puller, it rotates the wrong direction. Then you switch leads to rotate the right way, but the blade is backward. Then you pull the blade off and flip it over to have correct blade profile for best efficiency. You can use it for either pusher or puller, but you have to set it up with the correct combination of motor orientation, motor rotation, and blade orientation.
Barney Gaylord

My fan came off a Tiumph Tr3a and it was mounted in front of the rad, with its blue wire connected to supply and the black wire to earth. (The Tr is converted neg- earth). This way it was rotating clockwise, looking at it from the front of the car, with the blades pulling air from outside the front grille and through the rad matrix. Mounting it on my MGA (being Pos+ earth), when I connected the wires, blue to supply and black to earth, the blades rotated anti-clockwise with no effect at all. I reversed the wires, (black to supply and blue to to earth), the blades were now turning clockwise, their normal direction of rotation as indicated by an arrow on top of its plastic frame. Am I right in saying that if the fan was mounted behind the fan as Siggi suggested, it will be pulling HOT AIR from the engine and blowing it through the radiator. Surely this would heat the coolant in the rad much more rapidly than normal thus negating the cooling effect of the rad. I always thought that pulling COLD AIR from outside and onto the rad will keep the liquid fairly cool to circulate inside the engine thus preventing it from overheating. Thank you for all your inputs and any further comments on this subject are always welcome.

Frank
F Camilleri

Frank said: "Surely this would heat the coolant in the rad much more rapidly than normal thus negating the cooling effect of the rad. "

Not really, the radiator will still cool but not any where near efficiently. This will overheat the marginal MGA system. As long as the air temp in the engine compartment is lower than the coolant temp (~190 deg) the radiator will lower the coolant temp, albeit, minimally. Do not do this. Maybe this is what you meant.

Regardless of whether the fan is in front of or behind the radiator, if the fan is turning in the direction it was designed for as indicated by the arrow, and the air flow is from the front of the radiator to the rear, then all is well. You have the wiring correct with black to supply and blue to to earth. BTW, from my understanding, only some Kenlowe fans have reversible fan blades. It is model and size dependent.
Chuck Schaefer

Frank

See my schematic. Placing the fan in front or behind the radiator will draw air through from the front of the car, provided the fan is still orientated the same way round. It is only if you turn the fan around when relocating behind the radiator would the air be pushed forward (image 3). This all assumes that the wiring remains the same. In the third image you would then have to swap the wiring over again for the fan to suck air from the front (reversing fan rotation direction).

Steve

Steve Gyles

Modified schematic attached.

Steve

Steve Gyles

Steve, the fan I have, which is a Kenlowe fan, can only be mounted one of two ways. One way is attach it to the front of the rad with clockwise rotation of the blades. The other way is to attach it to the rear of the rad, again with the blades turning clockwise. Either way the fan will act as a puller. The only difference is that being mounted on the front it pulls cold ambient air and pushes it through the rad fins, while if mounted on the rear it pulls heat from the engine and pushes it through the rad fins. Looking at it logically, pulling cold air from outside and onto the rad will have a cooling effect on the rad coolant, whilst pulling engine heat onto the rad matrix will keep the coolant constantly hot. It is important to note that the fan blades cannot be turned around. The fan frame is not constructed for this. Secondly, for the fan to be effective its blades have to be turning in a clockwise direction only. If the wires are reversed its direction of rotation is also reversed but the blades will be non-effective.

Frank
F Camilleri

some comments....
It is more efficient to have the fan on the engine side ( provided of course that it pulls cool air from the car front through the radiator)
I looked at large number of fans and could not find one that could be put in above position without changing the pulley arrangement. I did not want to do this as it is wise to keep the belt driven fan in the boot.
Mounting the fan on the front of the raiator is the practical way to go provided you mount it directly on the face of the radiator so the air has to pass through the radiatorand no just circulate around the fan ( I have seen this dorkish arrangement on other cars....not MGAs of course ).
Neil Ferguson

Hi Frank,

sorry for the delay. Here's the pics of my fan installation. It's only the first version and is a bit rough and ready, but I think yo should get the idea.

Cheers,

Grant :-)

G Hudson

Hi Frank,

here's the base.

cheers,

Grant :-)

G Hudson

I would like to add a further complication.
On DC electric motors reversing the positive and negative leads only reverses the fan direction if the field magnets are not coil wound.
If the field magnets are coil wound the current is reversed in the field coils as well as the armature and the motor will still turn in the same direction.
Is this correct?

Mick
M F Anderson

Grant....I have to say that the arrangement you show looks excellent from the support/structural perpective but less than ideal from the cooling air movement perspective...reasons....
These fans are basically very simple high vol and ultra low DeltaP compressors and their 'characteristics' mean that they will seek the least resistance to airflow . This in turn means that if you leave a gap between the radiator front face and the fan exit much of the air will recycle from the exit to the entrance of the fan....you seem to have such a gap.
Some air will go through the radiator but nowhere as much as if you bridged the gap with a seal of some type and forced the fan to operate at a different point on its 'characteristic' curve of airvol v DeltaP.

Neil Ferguson

Neil,

thanks! Well spotted - the gap is one of the "tweaks" I'm working on, as I realised after fitting it that the fan should butt up to the rad.

cheers,

Grant :-)
G Hudson

Grant..I think if you used a strip of sealing material ( such as the windscreen sealing rubber .. thick type..US Moss Part type 280-735....or similar..it comes in about 2inch wide strips and I have used often for jobs on the car ) and fixed it around circumference of the fan inside ( if room around fan blades) or most likely outside and had it just touching the radiator front to form an extended shroud you would have close to perfection ( and that is a difficult state to reach!).
I know after I fitted my fans close to radiator front and turned on in the garage there was a veritable gale through to the the engine bay. Great stuff!!!
Neil
Neil Ferguson

Grant, your set up looks fine to me, looks very neat. But as Neal pointed out with a gap between fan and rad the effeciency of the fan is greatly reduced. I have attached my fan temporarily using plastic tie belts and tied it to the top tank, one on either side, and one round the bottom tank. The diameter of the fan frame is too large to fit flush against the rad matrix, and therefore I too ended up with a inch or so gap between fan and rad. As I said this is only a temporary set-up. I am only trying a fan which came off a TR3A. I will remove it again and fix a rubber strip around the circular part of the frame, and this would close the gap nicely. My intention is that if this fan is effective, and I will notice an improvement in engine temperature (i.e., engine running cooler), I will fit a slightly smaller fan that would mount flush to the rad. I like your pre-fabricated bracket, is that ss or aluminium? Looking at you second pic, I cannot figure out how you attached the fan at the base. Or am I to assume that there is no fixing there?


F Camilleri

Guys.....I reported some time ago on a thread that I fitted two smaller diameter fans to mine before last Oz summer to get good face coverage on the radiator and it has been working very well here in Oz. I had to scout around for fans that would fit flush on radiator but final assembley..attch pics..one inside car and other of assembley ( need to take radiator out to do a neat job )

Neil Ferguson

..and other pic.

Neil Ferguson

Neal, that's a brilliant set up you have there. I may also opt for twin fans. If I may ask, what is the external diameter of the fans you used? I would presume that both fans pull cold outside air through the grille.

Frank
F Camilleri

Frank....see Barneys site CO-111 as follows..
http://www.mgaguru.com/mgtech/cooling/cool_111.htm.
h
He has all the details of the fans and the set up for the dual (inch fans...
neil
Neil Ferguson

Frank..message was supposed to read ' dual 9 inch fans'....and in answer to your other query the fans pull cool air from the grille and push very very strongly through the radiator independent of road speed . When they click in (on the thermostat control) the coolant temp reduces very rapidly ...
Good luck
Neil
Neil Ferguson

Thanks Neal, I read through CO-111 on Barney's site. Extremely well detailed and very easy to understand. I saved a copy on my documents files for future reference.

Frank
F Camilleri

Neil Ferguson's dual electric fan setup has inspired me and I am planning on duplicating his fan installation.

Neil, it has been 8 years since you installed the two Davies fans in your MGA. May I ask you whether it has held up and if you'd do the same installation? Or would you change something today?

I wish you all a great autumn.

Thanks and regards,
Hans
Hansueli Ryser

Micks post in this forum set me on the road to fitting a similar set of twin 9" fans to my car.

His fans work brilliantly on an MGA and they supply more than enough cooling capacity to keep the engines temperature under control. I now have a highly tuned 140 bhp 1950cc engine in my car and the twin fans can easily cope with this.

So thanks for telling us all about this Mick.

I wrote an article for an MGA magazine about my experiments with the cooling system wjich includes using a more efficient plastic fan, a single 10" fan and finally the twin 9" fans.

If anyone would like a copy I would be pleased to send them one.

Cheers
Colyn
Colyn Firth

Hi Colyn, yes I would be grateful if you can send me a copy. Many thanks.

Frank
F. Camilleri

No problem Frank,I will send you an email.
Cheers
Colyn
Colyn Firth

Hi Frank,
I also have a 1950cc engine fairly highly tuned and run two 9 inch fans controlled by a thermo switch in the radiator set to come on at 190.00 degrees plus a MGB 7 blade plastic fan. The engine runs at 180 degrees normally so the fans only come on if I get stuck in traffic.
Regards
David
D M SPEAK

David
you should try taking off the engine driven fan and running with only the twin-fan set up. I think you will find that they are well capable of keeing your engine cool, and you will gain up to 7 bhp that the engine fan uses up too.

My fans only ever switch on when the car is stopped in traffic when the temp gets above 195 degrees.

On one occasion i was surprised to see that the temp gauge was showing a steady 165 degrees even though it was a very hot day, around 85 degrees. I realised that I had switched the fan overide switch on by mistake and the fans were running continually.

So there is more than adequate cooling capacity with the twin-fan set up.
Once I realised this I stopped carrying the engine driven fan around in the boot.
Cheers
Colyn
Colyn Firth

7 bhp ???
Where did that come from?
Art Pearse

Hi Art
A few years ago my car was being set up on Peter Burgess's dyno, it had the plastic NTG engine driven fan fitted at that time and (IIRC), Peter told me that this particular fan would probably use up to around 7 bhp.

It is a bit bigger diameter and it has much better blade design than the standard metal fan and it certainly moves very much more air than the std one.
Fitting id immediately dropped the average running temperature by 10 degrees F.

The main reason I fitted the twin fans was to save this power loss.

This is link to MGA Guru with pictures of the NTG fan.
http://mgaguru.com/mgtech/cooling/cool_208.htm

Cheers
Colyn
Colyn Firth

Quite impressive. Even so, a 7HP industrial fan would ventilate a warehouse!
Art Pearse

Hansueli.......I have not changed my original set up with twin fans.....no need as it continues to work well. Pleased to see other mga souls have modified this way...
Neil Ferguson

Hi Colyn,

thanks for the copy of your article on the installation of twin 9" fans. It is very clear and easy to understand.

What I would like to know is the cost of two fans, and the cost of the temperature control unit. I have a standard MGA radiator, and I am hoping that the two fans will fit side by side on the front of the rad.

Colyn would you kindly to tell me the source where you bought yours.

Frank

F. Camilleri

Frank, I bought my Davies-Craig fans from Maw Solutions who are the UK distributors of the fans which are actually made in Australia.
I think they are around
Colyn Firth

Colyn,
"instead of the 15 degrees of my present Revotec switch." - is that 15C(?) as I thought Revotec told me 5C but 15C would tie in more with my (C-N-H) gauge needle movement.
Cheers, Nigel
Nigel Atkins

Hi Nigel,
I measured the 15 degree range between on and off (or Hysteresis) that my Revotec thermostatic switch has, in degrees Fahrenheit.
This is mainly because my MGAs temperature gauge is marked in degrees Fahrenheit.

I hope that helps.

Cheers
Colyn
Colyn Firth

Hi Colyn,
I thought that might be the case but was hoping not as it would explain the gap the needle on my gauge gives but as there are no actual graduation markings (1973 midget) and the gauge doesn't seem that well calibrated and possibly I'd misheard the chap at Revotec, so I thought I'd ask you.

Google was also telling me that 5C was about 8-9F so I didn't know how accurate the Revotec switch might be or its tolerance or again if I misheard 5C.

I'm on my second Revotec electronic fan controller and both seem(ed) to switch off later and lower down the gauge than I'd like for the settings I tried - but as I tell my wife about the fuel gauge "it's only a gauge not an accurate". :)

Cheers for your help, Nigel.


Nigel Atkins

Nigel
I do have a Davies Craig Dual Fan Digital controller (Model 0444) in my garage which I bought over a year ago.
I thought it would control the coolant temperature between a narrower range, the ideally 10 degrees F. The ideal for my car would be for the fans to switch on at 195 degrees and off again at 185 degrees.

However, it turns out that this Digital controller has a similar 15 degree range to my present Revotec switch and so it would not really be any improvement.

I am still searching for a controller that will let me adjust both the on and the off temperatures and so until I find one, I may as well continue with the Revotec switch.

Cheers
Colyn
Colyn Firth

Colyn,
I've no idea how accurate the switch parameters are 10f might be too tight for cost and reliability. You could check with Revotec technical as I'm sure (but I could be wrong) that I was told 5c.

On my gauge the difference between on and off would look more like 10-15c.
Nigel Atkins

Personally a range of 10 to 15c sounds fine. Why have the fan kicking in and out frequently.? 5c sounds much too tight...
The engine is fine over this range if upper limit is set at 195 c ..even higher .
Possibly a little too much mental vernier control?
Neil Ferguson

Neil,
the narrow range I am looking for is down to two things,

1- I want the fans to cut in at around 195 degrees (my engine rarely ever gets this hot except when stood in traffic, it normally runs between 170 -185 and so the fans stay off.

2- The 15 degrees range that my switch has means that the fans don't switch off until the temp drops to below 185 degrees.

The twin fans are easily capable of this, if I leave the overide switch on, they will drop the temp to 170 or less.

But my ultimate aim is to only run the fans when the engine needs cooling and to me, at 185 degrees the engine doesnt really need cooling.

So if I could find a switch with a range of 5 to 8 degrees or so, then the fans would switch on at 195 and off around the 188 to 190 mark.

Remember my aim was to only have the fans running when the engine needs cooling so as reduce power losses and this was more important to me with my previous engine which had 106 bhp.

The 1950cc engine I have now gives 140 bhp and so power losses are now not my main concern.
But as I now get between 22 and 24 mpg instead of 28 to 30, then using very occasionally running twin-electric fans instead of the continually running engine driven fan can only help reduce power wastage and therefore maybe improve fuel consumption a little.

Cheers
Colyn
Colyn Firth

Colyn,
with twin fans the possibilities are more, perhaps have the fans switch on and off at different temperatures. Or if the one fan is enough normally have one on a stat and the other on a manual switch. Or have the fans operate at two speeds/power levels.

I don't have anywhere near 106bhp let alone 140bhp in my Midget so I think when my uprated Revotec 9" fan cuts in it has the uprated alternator working harder taking power from the engine which has the engine getting slightly warmer so the fan stays on slightly longer - each creating work for itself and the other. :) I don't think there's much if any engine power gain from my swapping from engine driven to electric fan - but the electric fan isn't constantly running so an overall gain plus the warm up and not over-cooling benefits for the engine.

With the switches I don't know what the tolerance of accuracy are - which has made me think of the water stat and how close that might be to the fan stat allowing for their various tolerances.

As an example, info from just one manufacturer, a 180f water stat may have a +/-3f tolerance so starts to open at between 177-183f. The stat is fully open about 15-20 degrees above its rated temperature, so fully up at 192-203f.
http://www.stant.com/index.php/english/products/consumer-products/thermostats/abcs-thermostats/

If the switch stat actually operates too close to the water stat then you could get a cycling of on and off between them.

As you now have a more powerful engine that produces more heat if you've not already done so it might pay you to have a water stat of a lower rating.

Just as an example. Yesterday it was dry and sunny so a roof down run to a country pub for food and real ale was called for. It was about 9-10c weather temperature, speeds of generally 55mph and less. On my inaccurate gauge I've roughly marked below where the needle was when the fan cuts in and out.

Cheers.


Nigel Atkins

Davis Craig fans only draw about 80w each... so total 160w . This is equivalent to about 0.22 HP . The draw on engine power is also smoothed by the electrical supply system...unlike the ditect drive pully fan.
Cant really believe these fans will affect performance or fuel economy in any real way....
NB Someone mentioned previously that a pulley fan pulls 7hp ...difficult to accept .
Neil Ferguson

Sorry, my comment was meant as a bit tongue-in-check, with the :) at the end. Overall I'd guess there'd probably be a power gain from removing the engine driven fan and swapping to electric, plus as I put other benefits. The gain I'd suggest on my Midget isn't much if any when my Revotec fan is running bearing in mind my car has nowhere near 106bhp let alone 140bhp and the Revotec high power fan I have runs at an approx working current of 8.5amps, I can definitely tell when it cuts in at idle.

I'm a fan (pun) of electric fan(s) instead of engine driven fan for classic cars that are regularly used all year round. I've run with only an electric fan fitted for many years. I'm not sure I'd bother for a car used mainly only for occasional use.

My point would be that electric fan(s) have benefits over engine driven but I don't think a very small gain in power (that I get, anyway) for road use is worth mentioning as I think regular full servicing and maintenance and regularly driving the car on reasonable length journeys would get greater power gains. To a non-technical person like me 7hp sounds a great deal to gain even if the engine-driven fan was bent and also significantly out balance.

My post was more about Colyn perhaps gaining more control over his electric fans' switch by whatever water stat is used.

Different things work for different people and different cars it's what makes things interesting.

Nigel Atkins

It was a few years ago that I had my car on Peter Burgess's dyno and although I do recall him saying that the big NTG engine driven fan I was using then was using up a surprising amount of bhp, I have admit that I dont have perfect recall of the exact number Peter , hence my use of (IIRC) in my post.

However, I do though remember thinking at the time that the power gained by removing my big NTG fan was the equivalent of a 10% power increase on the original MGA 1500 engine (approx 70 bhp) and certainly a very easy way to get it.

I will email Peter to see if he has a ballpark figure for the fans power usage and let you all know.

I dont suppose anyone has ever done a back to back dyno runs, one with an NTG fan fitted and one without.

I am though due to take my car back to Peters for a dyno engine set-up in the next few months.
Whilst I am there I will see if I can fit the NTG fan for the 1st run and then remove it for the 2nd to see if his dyno can detect the difference between the two.

The other reason for my swapping the NTG fan for the twin-electric set up was that it was surprisingly noisy in operation, you could hear a "woo woo" howling noise when you revved it which I didn't like too much, it sounded more like a double-decker bus than a sports car.

Apologies if my 7 bhp figure turns out to down to my suspect memory.

I will let you all know.

Thanks for the feedback Neil and Nigel

Cheers
Colyn

Colyn Firth

I just had a reply from Peter Burgess about the power losses caused by an engine driven fan.

He said that the standard metal fan uses up 2 to 3 bhp but has no info on my bigger, more efficient NTG fan.

I will see if he will let me do the back to back dyno runs with and without the fan fitted.

Cheers
Colyn
Colyn Firth

Colyn

https://www.haydenauto.com/Featured%20Products-Digital%20Fan%20Controller/Content.aspx

Dominic Clancy

Thanks Dominic
your link doesn't connect but I cut and pasted it into Google and it opened up the Hayden Auto website just fine.

Their Digital fan controller seems to be the only one I have ever seen that has the 10 degree hysteresis that I am looking for. It looks ideal for me.

Interestingly, it also provides a gradual start up and a gradual shut down to the fans which I cant see will be a problem but I am not sure why they have decided to do this.

Thanks again.

I will check this out.

Cheers
Colyn
Colyn Firth

Colyn,
I almost put that a way to find the loss was on a rolling road but thought that might be seen as a facetious remark.

I'm sure Peter would be up for the investigative work on your fan. My next visit will investigate whether blue or red HT leads are better. Last time I was in Peter and Keith had to show me how to properly use a feeler gauge after I'd set up the tappets and plugs, I was given a special tool but fear it's too technical for me.

The unit Domonic has linked to would give you the two stage fan operation (rather than the graduated shut down), the soft start I'd guess but don't know might be to easy the life of the fan motor and switching.

When that chap built the MGA V8 roadster/speedster(?) how did he control the heat?

(One time my neighbour's mate offered to build me a MGA with a V8 as he had a spare RV8 engine and one, if not more, spare A body/chassis.)

Getting the engine and exhaust heat out of the engine bay would always help of course, IIRC they cut holes in the inner wings for RV8 (b) car.

Just out of interest what temperature water stat are you using at the moment?

Cheers.


Nigel Atkins

I did ask Peter if he would mind doing a back to back run with the fan on and the fan off and he seemed quite keen to try this.
I suppose it would be good for him to know how much power this fan uses.
I will just gave to practice removing the fan in a hurry so I don't waste too much of Peters valuable dyno time.
Having hands like shovels doesn't help too much :-)

I am going to see if I can get hold of one of the Hayden Autos thermostatic fan controllers and fit it over the winter. I will let you know how that works out.

I plan to visit Peters Dyno in March ( he is always booked well ahead) and I will post the results of any tests that we can do.

Nigel, I run an 180F thermostat (82C) and it works fine, I suppose the thermostat only controls how cool the engine gets and doesn't affect how hot it can get.

The standard MGA rad cools my 140 bhp motor just fine, I did wonder about this at first but then I had this thought.
If my logic is correct, I supposed that the power it takes to move my MGA along at say 70 mph is the same with either a 106 bhp 1850cc engine or a 1950cc engine and so the heat output will be very much the same.

I think it would take a flat-out track test to tell if the cooling system can cope, but my feeling is that it would cope very well.

Cheers
Colyn
Colyn Firth

Re- fan HP
The hp used by the engine fan is surely comparable to what a good electric fan will consume.
Per HP, 746 watts at 12 V converts to 62 amps
What is the current draw on a decent electric fan? Not this high I would wager!
Art Pearse

Colyn,
the information might help Peter but I'm sure he'd enjoy finding out.

Please bear in mind I'm totally non-technical so could well be wrong and often am.

The water stat does effect the engine running temperature but if it's working properly once it is fully open that's it, until it starts to close again with coolant er, cooling. I was just thinking if it's operating temperature is too close to the operating temperature of the fan switch they could cycle with/against each other. The idea of the stats is to help keep the engine running temperature within a range. I'm not suggesting you have the problem but excessive heat is best avoided rather than deal with, once it builds it can be difficult to contain.

The water stat, fan switch and temperature gauge tend to be in different locations in the engine and cooling system so their figures aren't directly related. I've no idea where you'd measure from for an exact figure.

As you say, subject to engine related variations, the amount of power and heat will be the same to get your car through the air at 70mph (and probably a lot less than you'd imagine on a flat road at fixed speed).

The engines run well within a range of temperature so unless your racing I don't think there's a need to be too critical, I think that's one of the reasons the numbers disappeared off the water temperature gauge to save owners worrying too much.

Cheers.
Nigel Atkins

Art,
my Davies-Craig 9" fans draw 5 amps each when they are running at full speed (this spikes up to 12 amps each on start-up but this is only for half a second or so)

I'm not sure how much bhp 10 amps equates too, but bear in mind that my fans only ever run when the car has been stationary in traffic for 5 minutes or so and they only stay on for a couple of minutes until the temperature drops to around 185F. They scarcely ever run once the car is on the move.

An engine driven fan runs continually whether the engine needs cooling or not and so it is continually using up bhp.


Nigel, I suppose I didn't word my description too well of how the thermostat affects the water temperature, I was trying to say that, once it opens, it doesn't really have any real bearing on engine temperature.

I should have said that it is there to bring the engine up to the proper running temperature as fast as possible.


Colyn
Colyn Firth

Colyn,
it's very likely I misunderstood you and I often don't make myself clear, even to myself sometimes.

I'm grateful to you for doing the work on this and interested in the results.

Yes once the water stat is fully open then it's work is finished for the time being but if it's working correctly it will start to close up if if things get cold enough or obviously when the engine has cooled from lack of use. Also the stat isn't on and off like a switch. In winter on runs the needle on my gauge can be nearer 'C' than 'N', IF my gauge was accurate, IT ISN'T, it'd be 130f-140f or below.

Bear in mind my (possible) example from Stant earlier with a 180f (Stant) stat that (possibly) is not fully open until 192-203f. I've no idea of the coolant temperature differences between the stat, switch and gauge locations and any overlaps.

With the HP of the electric fans to my non-technical mind the electric power isn't directly related to engine HP as the fans are powered by the battery/alternator which also add their own drag/load to the engine plus pulleys and belt.

Be interesting to see the dyno results.

I'd ask Keith if during the run he'd spray lubricant on the pulley shafts just to see the look on his face at this request. :)

Nigel Atkins

Colyn

I noticed this comment in an article about auto fans.
https://www.allpar.com/fix/engines/fans.html
"For various reasons related to airflow, solid fans use much more power and fuel in dyno tests than when the car is actually being run and wind is rushing past the blades. Those magazine articles bellowing about “10 whole entire horsepower to spin the fan” at the equivalent of 65 mph are, though, grossly overstated."

So a dyno test might not tell you much. Also I doubt whether a fixed fan would use much more power than an electric one I.e approx. 10A x 12V = 120Watts. The fixed fan has more inertia so uses more power to accelerate and is running continuously shifting air but I can't see what other major loads would consume more power unless its shifting a lot more air than an electric one.

John Francis

I wish I was an aerodynamicist. However, something inside me says that with a car running at speed and an electric fan not running there is reduced airflow through the grill. The result is a slight build up of thickness of stagnant air around the snout. This causes friction to the free flowing air resulting in increased drag. The mechanical engine driven fan sucks more flow through the snout, reducing the thickness of the stagnant boundary layer air, resulting in slightly less drag. Overall I think in terms of loss engine power the 2 options balance each other out.

Steve

PS. My engine driven asymmetric 7-blade fan and origin core radiator still kept me below 180 in all the high summer temps in the UK, even crawling and shortish queues. Highest I ever saw was 195 when stationary for 10 mins.
Steve Gyles

thermometers reasons related to airflow, solid fans use much more power and fuel in dyno tests than when the car is actually being run and wind is rushing past the blades. Those magazine articles bellowing about
Colyn Firth

Interesting article but it does seem slanted towards bigger more laden cars than the humble simpler, lighter engine'd English sportscars we're used to.

With the various rolling roads I've been on there's been plenty of air to the engine if not the car as large (don't know the HP) fan units are wheeled in front of the rad grille so I wouldn't have thought, but don't know, that there was that much difference to going down the road in that respect at least.

Steve I think your probably right to an extent, but you'd only know for sure and to want extent if someone has done wind/smoke tests for MGAs with forward rad fans. With '73 Midget as it's like a brick anyway I don't think the additional brag from the electric fan and its position would be that significant. A, B, C and Spridgets have their rad reasonable recessed with a box like filter for the air to the rad, then there's the number plate position and twin horns disrupting direct airflow too. Daniel Stapleton done a book with such things in for the Spridget and an overseas owner done some tests to see what would keep the temperature down on his bitsa, mainly vents for his IIRC.

If I believed my temperature gauge it doesn't go over the equivalent of 190f and can show equivalent to 130f in winter - but I don't believe it either time. :)

Nigel Atkins

Colyn, thanks for the amperage data. OK, so 2 decent electric fans with at least the air capacity of the fixed fan consume 120W or about 0.16 hp.
Let's allow for the dynamo having to raise this from engine power at about say 75% efficiency, putting a load on the motor of 0.22 hp when on electric only.
From the 0.16 hp electrical load and assuming a motor efficiency of 0.75, I estimate the mechanical energy into the air is only 0.12 hp. The fixed fan must also be in this ball park.
Art Pearse

As stated in the article it certainly makes good sense that the fixed fan uses more power in stationary air.

As the air speed increases the fan will add less and less speed to the air, eventually reach a neutral point where it is just going at the speed the air would rotate it. At this point the only power consumed will be in mechanical losses in the fan itself. Beyond this the the air will start actually driving the fan (like a wind turbine) adding power to the engine rather than taking it.I have no real idea at what air speed the fan reaches neutral point and I guess it is well beyond the max speed of an MGA. But power consumption by the fan will certainly reduce with air speed.

Of course all the above applies to an electric fan if it has a constant running speed. Although in this case after the neutral speed a DC motor will turn into a generator.

I suppose this means a rolling road is of little use here unless it is in a wind tunnel!

Paul
Paul Dean

I have been having many a quiet chuckle to myself with all the preceding posts about power loss associated with fans. It is insignificant when, at the back of the bonnet the MGA has an almighty slab windscreen set at about 44 degrees to the horizontal. Surely that dwarfs the minuscule power loss by any fan configuration. My sports windscreen has Le Mans stanchions that are further raked by about 4 degrees. Combined with the lower frontal screen area the drag reduction is significant and alters enormously the thickness of stagnant boundary layer air from the snout to the foot of the windscreen, improving laminar flow and reducing drag. I am guessing (unproven by me) that it also improves airflow into the snout. Probably one of the reasons my car always runs cooler than many stock MGAs.

If I was to redesign an MGA my priority would be to rake the slab windscreen to the Le Mans measurement and alter the soft top to suit.

Steve
Steve Gyles

I understand where you are coming from Steve but it would be awfully quiet on here if Frank hadn't set me off again on this subject and my twin-fans which are one of one of my pet projects :-).

I must admit that the power loss issue is not really so important to me now that I have 140 bhp to play with, but the cooling capacity of the twin-fans is certainly well on top of the job and I am more than happy with them.

I often look on the USA based MG Experience MGA forum and I too smile every time someone speaks about fitting a more powerful engine and a 3.9 diff to make their MGA into a high speed motorway cruiser.

My car is more than capable nowadays of cruising all day at 90 to 100 mph, but, my ears are not! After about 20 minutes at high speed the buffeting caused by the windscreen is hard to take and I find that I have unconsciously slowed to around 65 or 70 mph which is a much more comfortable experience.

I can see how your Le Mans sports screen would improve the airflow over the car and significantly reduce the buffeting.
Im sure that also probably explains why the 1955 Le Mans MGAs with their windscreens removed had such a high top speed.

I would love to have a screen like yours on my car Steve but not being able to use the hood would make our long distance European tours even more of a challenge if we had to take motorcycle type water-proof clothing along with us.

I just cant see SWMBO going for it! :-)

Cheers
Colyn


Colyn Firth

Colyn

It was your comment about switching on your electric at speed and watching the temperature drop that got me thinking about all the air flow issues again. To me it speaks volumes that when you electric fan guys have your fans off you effectively cut off, say 50%, of the cooling capability, not helped by half an acre off plastic blocking the through flow of air.

There is another issue that I am quite happy to get shot down about if wrong. We all know with the conventional set up and the car running at speed air comes in through the top 'MGA' vents to feed/cool the carbs. Why does it flow inwards? Probably partly because of the force of air from the standard fan blasting the engine compartment. Speeded up air lowers the air pressure, hence the air being sucked inwards through the vents. If you don't get that blast of air from the fan (electric fan switched off) you will not get the same inward flow through the vents. You then have the likelihood of slightly warmer carbs and warmer air feeding them from the engine compartment. The result is when you stop/slow down/crawl you are likely to boil the fuel quicker than a conventional set-up?

Steve
Steve Gyles

Interesting stuff Steve, particularly about the engine fan maybe causing faster airflow through the engine compartment causing reduced air pressure under the bonnet.

Its kind of the opposite of my theory of airflow through there slowing down because it doesn't escape as quickly air is being forced in through the radiator.

One of us may be right, or we may both be wrong? :-)

It would be interesting to do back to back high speed runs first with an engine driven fan fitted and then with it removed to see if it is actually contributing towards cooling the engine at those speeds.
I personally think the engine fan still provides a significant proportion of the engine cooling at high road speeds.

The only way to find out is to be brave and actually try this, maybe next year on a warm summers day I will take a deep breath and give it a go.

My present twin-fans "half acre of plastic" doesn't appear to have had any noticeable effect on the running temperature either Steve, it still runs as cool as it did before when I had the engine fan fitted.
Nor has it ever been troubled by fuel vaporisation.

The strange thing is that when I first removed the engine driven fan and tried an electric fan I fitted a single 10" Revotec fan on the front of the rad, it caused the running temperature to go up by around 10 degrees overall. (To be honest the single electric fan wasnt really successful on its own as the gauge would often go up to the 200 mark in traffic)

However, when I then fitted the twin 9" Davies-Craig fans the running temperature dropped back to its previous low level.

I put this down to the fact that the beautifully made but quite thick Revotec mounting brackets actually masked the radiator much more than the twin fans do.
(Bear in mind that the twin fans don't run at all when the car is moving, only when the car has been stopped in traffic for a few minutes)

I will try to attach a picture showing the difference in between the single Revotec 10" fans (and brackets) and the twin 9" fans with no brackets.

Cheers
Colyn

PS I will seriously consider doing the experiment of running with engine fan and then with it removed.


Colyn Firth

The fan(s) are better fitted to the rear of the rad as the suction fans show as being more efficient and the fan and brackets may hold less collected debris than when fitted to the front.

My fan is front fitted and after only a couple of years at having to remove it to carry out servicing work I found a surprising amount of held debris behind particularly the fan body (straw, dead insects, I know exactly when I picked up the straw). Luckily the brackets on mine hardly intrude on the rad so nothing really there. Despite the debris I never noticed any difference to the temp gauge readings.

To frighten some (many?) I've never fitted an over ride switch to the electric fans I've had fitted to various classic cars, why have a dog and bark yourself and the only way to be fully backed up is to have a second car, same model and age of course, always follow you so that its a total back up, just in case, then a third to back up the second. :)

Colyn,
interesting photo of the Revotec brackets they now appear to be without the centre braces, so less blocking and debris, but I see there's a note in the instructions about getting the brackets fitted squarely which, if it wasn't in before, may mean they're worried about the newer brackets twisting if not fitted correctly because of the deletion of the centre braces. They also sell the brackets in black anodized finish, but not for Midgets shows the value difference of the cars. :)

https://www.revotec.com/acatalog/Negative-Earth-1.html
Nigel Atkins

That does look like a better design for the brackets than the original ones that came with my Revotec fan kit.
But to be absolutely honest, I would still probably ditch their brackets on an MGA and fit the fan to the radiator using the spring-loaded pull through tie kits.

The ones I used work well, they don't damage the rad or cause any obstruction to airflow and they are cheap enough to just snip them off and replace if you need to remove the fans for service.

Nigel, there is very little space between the fan pulley and the rad on an MGA and you would need to find a fan with a thickness of an inch or much less to fit it on the back of the rad.

Cheers
Colyn
Colyn Firth

Colyn,
which spring-loaded pull through tie kits did you use?

There's not much room behind the Midget rad but I discovered, after I'd refitted my fan of course, that if you swap to a 1500 rad cowling it gives half-inch (IIRC) rise which allows for a larger diameter slimline fan to fit the rear of the rad.

Unfortunately I deleted the photo I had of the hoard of dead insects on my rad after having the fan initially fitted for 5 years. A circle round the outer edge of the fan, clump in the centre and some where the top and bottom brackets were. A surprising amount I thought.

One of my pet subjects is thoroughly cleaning the whole (water) cooling/heating system including the engine block, heater matrix and to sort all related parts (including the fan, stat, belt, rad cap, etc.) but this subject is another full thread in the making as most find it OTT. :)


Nigel Atkins

Nigel
I used these fittings, they are spring loaded and so (in theory at least) you can't over tighten them.
They are both inexpensive.

demontweeks_pkpfkp01
Pitking Products Universal Fan Fitting Kit
£5.87INC VAT£4.89EX VAT

They also do these non spring loaded ones but I have never tried these.

demontweeks_glofpk01
Revotec Fan Pull Through Tie Kit
£7.14INC VAT£5.95EX VAT

I couldn't copy a link and so you will have to cut and paste these links into a search engine to find them.
(In fact you can just cut & paste one of them as they are next to each other on the Demon Tweeks website)

Cheers
Colyn

Colyn Firth

Thanks for that.

Try these hyperlinks -

Pitking Products Universal Fan Fitting Kit -
https://www.demon-tweeks.com/uk/pitking-products-universal-fan-fitting-kit-pkpfkp01/

Revotec Fan Pull Through Tie Kit -
https://www.demon-tweeks.com/uk/revotec-fan-pull-through-tie-kit-glofpk01/

Fan Pull Through Kit fitting video -
https://www.youtube.com/watch?v=SKMCQWsr2j0&feature=youtu.be

Seeing the video reminded me that on one of the very hot summer days this year the fan suddenly stopped just as I was pulling off from a set of traffic lights. Luckily I was able to pull over straight away and investigate. A large moth, much larger than the openings on the Midget rad grille, somehow went through an opening in the rad grille and stopped the fan as it was turning. There was only half of the moth on the rad the rest I couldn't see. I risked putting the ignition back on and the fan came straight on. I was only half a mile from home so I checked when I got there but could see no more.
Nigel Atkins

Cheers Nigel,
and thanks also to Frank for putting up with us rattle on about electric fans and stuff.

I think we have kind of beaten the subject to death, sorry Frank. :-)

Colyn
Colyn Firth

This thread was discussed between 27/07/2010 and 23/11/2018

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