Thermo fans

Hi PhilipA, yes the topic has been explored many times and I searched through and diligently read as many as I could find.
The only issue on installing electric fans that I could not find any information on is how to create the required space for the electric fans when I have a water pump who’s shaft was only 40 mm from the back of my radiator (note, all dimensions in my thread are with the radiator removed).

Fortunately Simon has been very helpful in pointing out that I need a later EFI model water pump that provides the additional space I need for the electric fans.

AU fan installed on radiator for those interested.
All of the mounting feet have been cut off along with any supporting ribs.
Attachment 185055
In particular, there is a mounting where the radiator outlet is.
Attachment 185056
With all of this removed I could fill the hole where the “boss” is and the radiator outlet goes neatly over the shroud.
Attachment 185057
Attachment 185058

The entire AU fan assembly is installed up side down compared to how it is on the Ford.
It is a remarkably good fit on the RRC radiator.

Regards
Phil

Yeah OK when on road but the point I was making is that the VC can pass many times the air flow than electric fans.

Up to maybe15 times but maybe only 10 times given the greater surface area of the electrics.

20 amps will probably need an alternator upgrade also unless he has the popular Bosch 85 amp conversion already, or those headlights will get mighty dim on a hot rainy night with aircon on.

I can recall one enthusiast poster many years ago who loved his electric fans until he got on a hot sand dune in low range.
Regards PhilipA
I had a Porsche 924 Turbo which I fitted VW fans to in a factory Porsche aircon shroud with them individually switched. They were brilliant but rubbish before I managed to get the shroud. But that was a car.

Quote:

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Originally Posted by PhilipA

Yeah OK when on road but the point I was making is that the VC can pass many times the air flow than electric fans.

Up to maybe15 times but maybe only 10 times given the greater surface area of the electrics.

20 amps will probably need an alternator upgrade also unless he has the popular Bosch 85 amp conversion already, or those headlights will get mighty dim on a hot rainy night with aircon on.

I can recall one enthusiast poster many years ago who loved his electric fans until he got on a hot sand dune in low range.
Regards PhilipA
I had a Porsche 924 Turbo which I fitted VW fans to in a factory Porsche aircon shroud with them individually switched. They were brilliant but rubbish before I managed to get the shroud. But that was a car.

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As someone who has actually used genuine fake EL thermo fans for 20 years, to cool a 350 on lpg using a stock RRC rad, I'll make some real life observations.

1. They cool far better than an engine driven fan when slogging in the bush because the fan speed is controlled by engine temp, rather than engine speed.

2. They don't have to pump as much air because they are way more efficient............

because they cover more surface area much more closely

because the outer edges of the fans are only a few mm from the shroud

3. I've only ever used a Bosch 55 amp alternator and have had no issues with power supply, apart from being aware of increased brush wear.

4. One fan 'failed' after about 100 thou of continuous use due to the brushes sticking in the motor. They were barely worn.

Double Chevron (Shane) posted an excellent wiring diagram for these fans some time ago.

cheers, DL

The biggest issue with thermofams is their operation being tied to a thermoswitch or a temp-sender/relay trigger arrangement.
Typically these have a trigger value in the range of 75-120ºC depending on the electronic package or sender type/value.
If not installed correctly, the sender will either trigger too late in the engines thermal load cycle or too frequently if installed in a position where the senders' range is narrower than the expected variation of the temperature and coolant flow rate.

So where they often fall short in an rrc application /use, is when they are incorrectly setup and used in a stationary or extreme low speed low rpm application, or with a poorly sorted electrical system with no increase in charging capacity or storage.

So many types of trigger/sensor setups available these days that in theory at least, a well-executed installation of thermofans should cater to just about any variable - but the reality is not quite the same truth - because the installation requires some actual research into airflow rates, air density and temperature and an acute knowledge of the engines coolant capacityu, thermal mass and heat dissipation factor.

This is all easily attainable, and in 99% of cases completely ignored by the end user wholesale, which leads to the endless complaints about systems not working properly or as a user expected.

The viscous coupling fan and shroud is a slightly more primitive and wholly mechanical method of a variable speed/load fan, which simply uses a clutched fluid coupling triggered by a bimetallic spring, which has a limited degree of adjustment in some cases and no adjustment in others.
Viscous coupled fans are efficient, but do draw a load mechanically, rather than electro-mechanically as is the case in an electric thermatic fan.

The disadvantages to a visco-coupled fan are in low-rpm high ambient temps, not at all dissimilar to the electric thermofan, however the visco-coupled fan suffers from being directly tied to engine rpm. When a vehicles cooling system is not operating at it's designed efficiency (i.e. not a well-maintained system) then the same issues of overheating occur - except that the visco-coupled fan is again directly tied to engine rpm, and it's operational efficiency when locked fully is only as good as the airflow at any given engine speed. Increase engine rpm, increase thermal load, may increase airflow, but airflow rate increase may not offset the thermal contribution by running engine at higher rpm.


The exact same can be said for thermofans when the airflow is suboptimal, except the primary load on the vehicle is electrical - and the alternator output is directly attributed to the Thermal load and the engine rpm. When the ambient temperature in the engine bay reaches a certain threshold, the alternator will de-rate and may not output it's full current for any given rpm, due to the thermal de-rating curve.

Again, increase engine rpm - increase heat, increases the de-rating level of the alternator, which reduces the output further, thus affecting the power delivery to the vehicles electrical circuits, one of which happens to be the thermofans used to cool the engine.

So you can all debate the relative merits and disadvantages of both until the cows come home. The facts however, are always there for any owner to observe, should they wish to learn.

Regardless of the type of cooling device used, when a fan is employed to create or increase airflow across a heat exchanger core, the fan needs to have a correctly designed venturi, the correct spacing from the heat exchanger core in order to prevent cavitation, reduce drag coefficients and provide the best possible airflow in both assisted and unassisted airflows across the exchanger core.

This is where the visco-coupled fan design provides an obvious lack of restriction in airflow for unassisted flow application. It's also why a visco-coupled fan was used instead of a direct driven fan or electric thermofan was chosen.
At the time of the vehicles production, electrically operated thermatic fans were far more primitive in their construction and operation, so a visco-coupled fan solution which was already a well-proven technology was used.

We're now more than 28 years past the expiration date of the vehicles production, so the 'rules' have changed somewhat.

Thermatic fans are now commonly PWM controlled brushless dc motors with highly efficient blade designs that do not impede airflow, and in many cases do not require a shroud of any kind. The intelligence is all in the controllers hysterisis loop and that is designed by engineers who know a thing or two.

Adaptation to an RRC nonetheless requires some consideration and planning. It may very well be the case that certain prefabricated solutions can be adapted to suit the operational requirements of the vehicle, but that does not mean they are optimal or the best or even a 'better' solution that what already existed in the original design. What they do depend on, as does any cooling solution, is a properly functional and perfectly sound cooling system, which also means every hose, every coolant passage and every mechanical device in that system be at it's optimal operational efficiency.

In other words - if anyone thinks that swapping out their visco-coupled fan for thermofans will wholesale improve the existing setup and fix a problem that is not directly related to a failed visco-coupling- they should be giving themselves a clip in the ear.

Unless that radiator is perfect inside, the thermostat and hoses are perfectly functional and the engines water pump, heater pipes, heater core and coolant passages in the block are absolutely spotless from corrosion, slime, scale and oil, then you're simply clutching at straws and wasting your time.

The visco-coupled fan is perfectly adequate when the rest of the system is in perfect working order.

If the coupling is slippy or the radiator has a bit of crud in it, or the thermostat doesn't open properly, or the heater core has a leak - or the header tank cap doesn't seal properly at pressure - then no thermofan will fix a runaway cooling system.

There's no debate - it is simply down to the facts.

Either know exactly what you are doing, or do the math and make it right if you don't. Ignoring the detail is what will get your goose cooked when the engine decides to become a piston-driven steam cleaner.

[thumbsupbig]

great post!
one thing maybe forgotten is that VCs have a bias to low revs and even when locked (by temp) peak out at maybe 2500-3000RPM as they are designed to shift air at low revs.
Many have found out this to their cost in shattered batteries and holed bonnets when they lock a VC by screwing the sides together and they fan blades seek their freedom.
regards PhilipA
THere also are reasons why D3 and D$ and 200LCs still do not have electric fans.

Manufacturers that use viscous fans do so because they are cheap and reliable. It is old tech that works.

But plenty of modern cars with more power than a RRC don’t use viscous fans anymore. My BMW, my wife’s Audi, even the Citroen and Peugeot with the TDV6 as used in the D3/D4 all just use electric thermo fans.

Set up and designed correctly they work perfectly well. Often these fans are no more than around 300W (when a single electric fan is used) on engines up to around 150kW. Volvo’s 232kW 4.4V8 in the XC90 uses a 600W electric fan.

A perfect solution would be to use both electric fans and a viscous fan as you can never have enough cooling in my opinion and a viscous fan is a good back up to the electric fans. But this does not mean a full electric fan set up can’t be made to work just as well, of course you do need to monitor engine temps (old cars don’t have ECU’s watching out for overheating).

I have installed the later water pump that now provides room for the electric fans.
Attachment 185230
I have assumed that the AU fans will perform significantly better than the two individual fans I had fitted on a previous RRC.
It had a P76 engine and LT95 4 speed with 0.996:1 high range transfer gears and performed faultlessly on and off road for many years.
As Ford have engineered these fans for the correct clearance between radiator and fan and the design of the fan blades and motor rating, I believe it should be effective.
I agree that no fan arrangement will cure a defective cooling system issue.

Time will tell for it’s suitability.

Regards
Phil

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Originally Posted by Phil 850

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I have assumed that the AU fans will perform significantly better than the two individual fans I had fitted on a previous RRC.
It had a P76 engine and LT95 4 speed with 0.996:1 high range transfer gears and performed faultlessly on and off road for many years.
As Ford have engineered these fans for the correct clearance between radiator and fan and the design of the fan blades and motor rating, I believe it should be effective.
I agree that no fan arrangement will cure a defective cooling system issue.

Time will tell for it’s suitability.

Regards
Phil

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The fans are useless on their own, it's the combination of the fans integrated WITH the shroud, i.e. the complete fan system.

Yeah Ford engineered this system for Oz conditions.

The stock AU 6 & 8 cylinder radiator measures around 660 x 42 x 28mm for an overall volume of cooling surface of 7.9 litres.

There are aftermarket Ford rads available for performance applications that have a core volume of 13 to 14 litres.

The stock RRC rad core measures 695 x 380 x 50mm for an overall volume of cooling surface of 13.2 litres.

As I've said in numerous posts in the past, one fan on my pos is on all the time and the other is run via an adjustable temp switch. Not ideal, but it works fine for me, one day I'll get around to putting in the other switch.

Even with a 55 amp alternator the stock heater fan switched to high drops the volts on the dash meter waaaay more than the second rad fan kicking in.

cheers, DL

Quote:

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Originally Posted by Phil 850

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AU fan installed on radiator for those interested.
All of the mounting feet have been cut off along with any supporting ribs.
Attachment 185055
Attachment 185058

The entire AU fan assembly is installed up side down compared to how it is on the Ford.
It is a remarkably good fit on the RRC radiator.

Regards
Phil

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Hi Phil,

I can see how you've done this, just a couple of suggestions.

On my set up I made 2 aluminium brackets that support the weight of the fan assembly either side, using the rad locating bolt mounts.

Attachment 185606

I'd suggest you do similar, or extend the right angle flange you've made for the bottom of the shroud so the weight is taken by the rubber grommets at the bottom / side of each rad tank.

RRC radiators are prone to splitting the seams between the core and the tanks in stock form. I suspect this is due to the weight being taken by the bolts either side rather than the grommets at the bottom, and the weight of the fans could worsen this.

cheers, DL

I have EL fans on my D1V8 and AU fans on my 4.6 SD1. Both are controlled by a Delta Current Controller, made by Brain Baskin in the US, where they are very popular with the muscle car crowd. They come with a dial to mount on the dash which lets you set the temp you want the engine to run at. The DCC does the rest, ramps the speed of the fans up and down to maintain a constant temp.

I think that's the advantage of the DC Controller - all the other fan controllers are on/off controllers AFAIK - they turn the fan on full at the preset high temp, and turns it off at the cool temp - so the fan is cycling on and off going from full speed to off. This is not really an issue at speeds above 40 mph when the fan is not really needed.
The DC Control unit is a variable speed controller - it varies the fan speed to maintain a constant coolant temp - it slowly speeds up as needed rather than pulling a lot of current to go full speed.
I also have the LED on my dash that tells me what the fan is doing - it changes color depending whether the fan is off (green) at partial speed (orange), and full speed (red) - works great
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