Electric Fan

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24 Nov 2014 21:07 #2 by Tony Lee
Tony Lee replied the topic: Electric Fan
Been discussed several times, but I think the consensus was that while you might manage normal city and highway driving, all day slogging through sand or other slow steep going in hot weather will result in problems.

Current fan only runs when needed so whatever power needed to run that is going to have to be replaced with power generated by a larger alternator.

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25 Nov 2014 04:57 #3 by Peter_n_Margaret
Peter_n_Margaret replied the topic: Electric Fan
#196 uses a fan from a Falcon, I reckon.
Can't remember. Been there 10 years.

Cheers, Peter.
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25 Nov 2014 06:41 #4 by dandjcr
dandjcr replied the topic: Electric Fan

OKABloke wrote: Puller Fan is around 20% more efficient than the same fan as a pusher.


I didn't actually believe this when I read it but David is right, there's tons of evidence on the net about it (something to do with laminar airflow from sucking rather than turbulent air produced by blowing).

But it is counterintuitive, when your face is hot you blow air on to it, you don't suck air away.

Car engines used to have engine driven puller fans, like the Oka, but electric fans are invariably pushers (on my cars anyway), presumably due to ease of installation.

But my problem is slightly different.

I suffer from overheating since my Oka (XT) air tunnel is stuffed with a/c condensers and fans so air flow is already impeded, especially pulling hard over slow terrain, but more importantly, on a hot day with the a/c on full blast, the air reaching the radiator is already extra hot and no amount of fan power can change that.



So my question is has anyone considered how to get extra cooling air into the tunnel without first passing through the a/c condenser system? Using a scupper from under the front bullbar? (Now that I've removed the thick plate where the bash plate was fixed).



I'm now leaning towards installing electric fans, since my viscous hub is not viscous-ing anymore, not to reduce engine power drain but because they'll work effectively at low speeds and lower engine revs.

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25 Nov 2014 08:16 #5 by TH
TH replied the topic: Electric Fan

dandjcr wrote:

OKABloke wrote: Puller Fan is around 20% more efficient than the same fan as a pusher.


I didn't actually believe this when I read it but David is right, there's tons of evidence on the net about it (something to do with laminar airflow from sucking rather than turbulent air produced by blowing).

But it is counterintuitive, when your face is hot you blow air on to it, you don't suck air away.

Car engines used to have engine driven puller fans, like the Oka, but electric fans are invariably pushers (on my cars anyway), presumably due to ease of installation.

But my problem is slightly different.

I suffer from overheating since my Oka (XT) air tunnel is stuffed with a/c condensers and fans so air flow is already impeded, especially pulling hard over slow terrain, but more importantly, on a hot day with the a/c on full blast, the air reaching the radiator is already extra hot and no amount of fan power can change that.



So my question is has anyone considered how to get extra cooling air into the tunnel without first passing through the a/c condenser system? Using a scupper from under the front bullbar? (Now that I've removed the thick plate where the bash plate was fixed).



I'm now leaning towards installing electric fans, since my viscous hub is not viscous-ing anymore, not to reduce engine power drain but because they'll work effectively at low speeds and lower engine revs.


I have been wondering about this also. The intercooler on #234 takes up the entire tunnel. I'm yet to venture out in 40'C temps but I think the old girl would struggle.

Cheers, Tony

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25 Nov 2014 10:33 - 25 Nov 2014 10:36 #6 by Dean and Kaye Howells
Dean and Kaye Howells replied the topic: Electric Fan
Hi Martyn, We had a couple of cooling issues on #413 a little while ago which turns out to be caused by a failed viscous coupling along with a sticky thermostat. Diagnosis was compounded/confused by a mis reading temperature gauge.

OKA Paul provided the viscous coupling and it certainly wasn't 'hundreds' of dollars though did need slight modification to work best. Engine thermostats are a consumable item, they are not designed to last forever and on the OKA are a bypass type which works very effectively. The radiator was removed and rodded several years ago and has run coolant/inhibitor since.

The long and the short of it is...why change a perfectly good (well designed and constructed) cooling system for a lashed together more complex (failure prone) ad hoc electrical one ?

OKA 413 has recently returned from another 'round Australia' jaunt, 17K Km of some very arduous travelling under some very hot and trying conditions. The temperature sat on a steady 82 degrees C (thermostat temp) all the way. :) Note. factory aircon was not used.

IMO you're best to fix what you've got. Can't talk much about the XT cooling system though, from memory a smaller radiator and an absolute bugger to work on.

Deano
Last Edit: 25 Nov 2014 10:36 by Dean and Kaye Howells.

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25 Nov 2014 11:00 #7 by Ralley
Ralley replied the topic: Electric Fan
I found the bearing in the hub of 169 was rough and it was going to cost a similar amount to get a new one. The bearing was also not available (similar to a water pump bearing). I ended up modifying what was there to take 4 normal ball bearings. It's since done 35000km with no problems. I also fitted a Davis Craig viscous hub.

Rob

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26 Nov 2014 09:07 - 26 Nov 2014 09:17 #8 by Dean and Kaye Howells
Dean and Kaye Howells replied the topic: Electric Fan
Thanks for the additional info Martyn, my original perception was that the viscous hub had failed.

As to the efficacy of the Perkins cooling system design, I'd note that after nearly 20 years (or more) of effective service for the hub bearing to fail hardly constitutes poor design / manufacture. More of a normal 'wear and tear' issue. That it was compounded by corroded fasteners/threads of the hub boss to the block/water jacket bolts is certainly a problem one could do without, but again, for a 20 year old engine not unusual.

What I'm asking here is whether changing from an engineered (for the Perkins) tried and proven design to a generic after market and more complex system is the best solution considering cost, efficiency and reliability/longevity ?

ie. would the damaged block threads have been OK with studs cemented in with a suitable Loctite/Stag type product that would not need to be again removed (for the life of the engine or another 20 years) or as you say drilled and tapped or by using helicoils ? I've replaced Land Rover 300 Tdi fan hub bearing assemblys which are very similar to the Perkins with a cut down (Ford) waterpump hub for a cheap, effective and sometimes better than new (original) solution.

My other concern is whether an electric fan can pump the same CFM's as an original fan when required. Without knowing what the original Perkins figure is seems a bit 'suck it and see'.

I couldn't find any current figures quoted for the Zirgo fan mentioned but even if the original fan uses a mere 1/2 HP when running this equates to a minimum additional 30 amps of alternator/battery load (at 100% efficiency) for an electric fan to match it. When considering the additional 'frailties' of an electric motor, thermostats, relays and high current wiring in a potential harsh off road environment I wonder if electric is the way to go ?

Whilst I've got nothing against a properly engineered thermo fan solution I can't see a reason to change from the tried and proven Perkins/OKA design. I assume there are benefits in changing to a thermo fan system, I just can't see what they are. :)


Deano :)
Last Edit: 26 Nov 2014 09:17 by Dean and Kaye Howells.
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26 Nov 2014 21:07 #9 by OKADOC
OKADOC replied the topic: Electric Fan
Throw out the t/stat, the water pump impeller , install a 150 litre per min electric water pump in the return radiator hose, throw another one in the essential spares box, (takes 15 min to change out) fit two 16 in suckers mounted on an air plenum built with a 75 mm space between core face and plenum fan base which creates even air flow pressures over the sqare face area of the heat exchanger . Fit a digital variable speed controller near driver position, wire to fans and water pump. Fill with glycol, start the old oiler, witness the water pump start slow revs and slowly ramp up until coolant reaches the set temperature on controller , then the fans will start slow revs and ramp up as and when required .
Easy way to efficiently control engine temps whilst operating and after shut down occurs, prevents heat sink.
But wait there's more, the removal of the drag of original fan and water pump will add min 12 hp more likely 15 with a bit of luck offset a little by the extra amps drawn on the alternator to run the show.Where do ya get it, Davies Craig .com.au .You won't be disappointed you did. Happy safe travels to all, Doc and Lyn
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27 Nov 2014 05:02 - 27 Nov 2014 05:24 #10 by dandjcr
dandjcr replied the topic: Electric Fan

OKADOC wrote: Throw out the t/stat, the water pump impeller , install a 150 litre per min electric water pump in the return radiator hose, throw another one in the essential spares box, (takes 15 min to change out) fit two 16 in suckers mounted on an air plenum built with a 75 mm space between core face and plenum fan base which creates even air flow pressures over the sqare face area of the heat exchanger . Fit a digital variable speed controller near driver position, wire to fans and water pump. Fill with glycol, start the old oiler, witness the water pump start slow revs and slowly ramp up until coolant reaches the set temperature on controller , then the fans will start slow revs and ramp up as and when required .
Easy way to efficiently control engine temps whilst operating and after shut down occurs, prevents heat sink.
But wait there's more, the removal of the drag of original fan and water pump will add min 12 hp more likely 15 with a bit of luck offset a little by the extra amps drawn on the alternator to run the show.Where do ya get it, Davies Craig .com.au .You won't be disappointed you did. Happy safe travels to all, Doc and Lyn


Doc you make a compelling (but not inexpensive) argument. There are several useful YouTube videos on the DaviesCraig website , especially this one which explains their philosophy.



I hadn't appreciated just how much power a mechanical water pump can take, not just the fan (1 KW=1.34 HP).



I'd recommend a bypass switch for the electronic controller so you can always power the water pump if the electronics fail.

Dual electric fans will also provide redundancy. [One of our a/c condenser fan motors failed during our last trip, when it was hot of course. Partial internal short circuit, started drawing 30 Amp, dragging the 12v down and blowing various fuses every few minutes, took a while to track down].

This just leaves the problem of getting more air to the radiator...

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28 Nov 2014 07:21 #11 by Paul Scherek
Paul Scherek replied the topic: Electric Fan
Martyn, in principle I think the electric route is brilliant. Both the pump water volume and the fan air volume can be set to exactly what is needed. Full cooling is available while stationary or crawling, and no power is wasted circulating more water than is needed. Temperature regulation is not by a wasteful thermostat re-directing pumped water away from the radiator path.

However.... I thanked Dean because he brought up the issue of power used. Having seen statements that the belt driven pump and fan can consume 10 horsepower, I too have wondered how an electric pump and fan can circulate enough air and water to give adequate cooling. Assuming the 10 hp figure is not just advertising hype, that works out to around 600 amps if 10 hp is supplied by a 12 volt electrical system. Clearly impossible.

So what is the answer? Are the belt driven systems really only 5% efficient? Even if this is the case, as Dean points out 30 amps is a big ask. Not impossible, but not totally desirable.

I add to all this that of all the vehicles I have ever used - lots - the Oka has the most effective cooling system. Under stinking hot sand dune conditions the temperature rises by only about 2 degrees. So I agree, in principle the electric route is great, but in practice the Oka system works really well and I can't see how an electric system can compete without seriously beefing up the alternator.

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28 Nov 2014 10:02 - 28 Nov 2014 10:03 #12 by outyonda
outyonda replied the topic: Electric Fan

OKADOC wrote: Throw out the t/stat, the water pump impeller , install a 150 litre per min electric water pump in the return radiator hose, throw another one in the essential spares box, (takes 15 min to change out) fit two 16 in suckers mounted on an air plenum built with a 75 mm space between core face and plenum fan base which creates even air flow pressures over the sqare face area of the heat exchanger . Fit a digital variable speed controller near driver position, wire to fans and water pump. Fill with glycol, start the old oiler, witness the water pump start slow revs and slowly ramp up until coolant reaches the set temperature on controller , then the fans will start slow revs and ramp up as and when required .
Easy way to efficiently control engine temps whilst operating and after shut down occurs, prevents heat sink.
But wait there's more, the removal of the drag of original fan and water pump will add min 12 hp more likely 15 with a bit of luck offset a little by the extra amps drawn on the alternator to run the show.Where do ya get it, Davies Craig .com.au .You won't be disappointed you did. Happy safe travels to all, Doc and Lyn


When every one is indoors with the AIR COND going flat out!!
OKA DOC's OKA's are still out there in the desert 50 degree heat working.

his system cools the big P400's & has done so for several years now!!

Moral of the story
the fan belt has done the job for years BUT
electric & technology is efficient, economical & good at the job!!

OKAs 091, 093, 094, 113, 346x6 & 405
Last Edit: 28 Nov 2014 10:03 by outyonda.

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28 Nov 2014 10:50 #13 by Dean and Kaye Howells
Dean and Kaye Howells replied the topic: Electric Fan
Hi again Martyn.........................an interesting response.

This time I think it's been your turn to 'mis understand' some of what's been said. :)

The suggestion that STUDS (using washers & nuts) can be used to replace bolts into partially damaged threads is not a substandard repair. A problem with re using bolts in this scenario is that when they are installed/removed the already damaged internal thread is further damaged, leading to failure. To replace these bolts with properly cemented in studs (Loctite products have been around for a long time and they have a product specifically designed for this purpose) can give a good solid bond between stud and block which does not risk further damage due to movement with the added bonus of forming a waterproof bond, if into the water jacket, which will also stop coolant leaking up the threads to cause further corrosion, coolant loss and oil contamination possibly leading to engine failure. The new studs and nuts now take the movement/wear and do not compromise the previously weakened and repaired bolt holes. Using nylock nuts here can also be a benefit as less torque is required to maintain a 'rattle free' connection which decreases the load on the repaired stud/thread connection. In some cases this setup can actually be stronger than the original as the wear/movement area is now steel to steel (stud & nut) not steel to cast (bolt and cast). Another benefit of this type of repair is that a new stud can actually use the complete length of threaded hole in the casting which may not have been the case when using a bolt. In this scenario a benefit is that the timing cover may not need to come off to make the repair.

Sorry about the long winded explanation here Martyn, just trying to give you a bit more detail :), I was not advocating some dodgy 'quick fix'.

Re the fan hub, with the number of people changing from Perkins to other engines it may be possible to pick up a good second hand hub for a lot less than the $700 quoted by Perkins Australia. It's been my experience that importing engine parts directly from the UK can be a lot cheaper than the local agents.

You quote me............................. "I've replaced Land Rover 300 Tdi fan hub bearing assembly's which are very similar to the Perkins with a cut down(Ford) waterpump hub for a cheap, effective and sometimes better than new (original) solution" and ask the question ......... "so it was ok then why not now to an Oka?"

This is precisely what I am advocating.

The Land Rover 300 Tdi engine has a similar hub bearing setup to the OKA and the same problem when it fails, the whole casting (timing cover) and bearing must be bought from Land Rover as one item for around the same $700 quoted for the OKA part. A cut down fan hub bearing from an EA, EB, ED falcon water pump is EXACTLY the same as the Land Rover unit with the benefit of a machined steel pulley boss as opposed to Land Rover's cast offering. I've done this repair several times for an all up cost of about $35. A significant saving with no compromise to quality, in fact a superior result with the better boss.

www.aulro.com/afvb/projects-tutorials/61...ing-solutions-4.html

This link explains it all and although Land Rover 300 Tdi oriented gives the general idea.

To answer your question..............." you have changed your front diff to LSD and your lighting to run through relays, two fuel gauges even air intake and exhaust all away from original because you wanted better performance, efficiency ease of operation etc so why not fan? "

A fair question.

1/. The front axle is a Dana 60 assembly made by Dana Spicer in the USA and imported by OKA for its vehicles. The LSD I've installed is the properly designed, engineered and constructed Dana Spicer option as outlined in the OKA service/repair manual. It is not a modification but a manufacturer option.

2/. The OKA's primitive head lighting system is an automotive design joke. Apart from, again, Land Rover, I don't think any automotive manufacturer has built a shoddy system like this since the early 70's. Like the daytime driving lights this improvement in lighting is an improvement in safety. It can all be returned to original in a few minutes as it all plugs in using the same plugs/sockets as the original OKA poor design.

I have no issue with design improvement modifications especially those which have no adverse impact on the running of the vehicle such as minor issues like lights, air cleaner/exhaust baffling but what I do think long and hard about is modifications to critical design areas such as the cooling system. The LT OKA has a very simple and well designed cooling system, when maintained correctly it runs flawlessly even under the most adverse conditions, as I said before.

"....I've got nothing against a properly engineered thermo fan solution, I can't see a reason to change from the tried and proven Perkins/OKA design. I assume there are benefits in changing to a thermo fan system, I just can't see what they are."

A comparatively complex electrical/electronic solution that significantly increase electrical load/stress or a simple tried and proven system ? I remain to be convinced but am open minded to progress, improvement and good engineering design.




Deano :)

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28 Nov 2014 11:29 #14 by TH
TH replied the topic: Electric Fan
I'd question the claimed hp requirements of mechanical pump. Just think of how much water a 6.5hp firefighter can move in a minute. I'd be surprised if it takes more than 2hp to circulate the system. So the electrical requiements, in theory, shouldn't be excessive.

Cheers, Tony

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28 Nov 2014 13:49 #15 by Dean and Kaye Howells
Dean and Kaye Howells replied the topic: Electric Fan

TH wrote: ................................. I'd be surprised if it takes more than 2hp to circulate the system. So the electrical requiements, in theory, shouldn't be excessive.


Hi Tony, 2 HP is the equivalent of approx. 1500 watts or 125 amps on a 12 volt system. This is the theoretical 'best case' value assuming no losses in generating the 2 HP at all.

This figure represents a massive additional load on the vehicles electrical system. OKA 413 has a Bosch 1280, 12 volt 80 amp alternator fitted. This figure (125 amp) represents a more than 50% overload of its maximum rating and does not take into account any other electrical load on the system.

This is why I am concerned about stress on the vehicle electrical system when using an electric fan/pump setup.

If indeed 2 HP is a realistic figure then an alternator with a minimum rating of at least 200 amps (250 would be better) would be needed. This would require a substantial upgrade of mounting, cabling and drive (dual belts minimum) and would be quite costly. There would IMO need to be some pretty significant comparative advantages to change to a system such as this.

Deano :)

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28 Nov 2014 18:02 - 30 Nov 2014 05:05 #16 by PeteFox
PeteFox replied the topic: Electric Fan
I've been sitting back biting my tongue in this one for about a week but I can't resist it.
Like death and taxes, the laws of physics are inescapable.
Unless Perkins have designed some monstrously inefficient fan / water pump setup then the following applies:

If the Perkins fan consumes a certain amount of power and the electric fan consumes a fraction of that power then the electric fan will move air at the same ratio. i.e. Under the same set of operating conditions a fan that uses say 25% of the power, moves 25% of the air. There is no such thing as free energy irrespective of the type of power used. There is no escaping this.

Also:
The claimed CFM performance of a fan is a meaningless statement unless there is also a statement about the pressure that the air is delivered at. That is how much air will it push through a radiator core.

Pete Fox OKA266 MultiCab
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28 Nov 2014 21:50 - 29 Nov 2014 06:05 #17 by dandjcr
dandjcr replied the topic: Electric Fan
The current consumption figure for the Davies Craig EP115 water pump "suitable for small, medium, large, high-performance and 4WD vehicles" is 10A max. Same for the EP150.

That's 138W at 13.8V or 0.2HP. See their spec sheet here .

The Davies Craig DSCL14 fan draws 13A at 13.8V or 0.24HP.

For comparison, 2 are recommended for the F350 so the total for a water pump and 2 fans would be 36A or 0.66HP. This would be the worst case and the average would be less using an electronic controller so the fans only run as necessary.

Alternators are around 50% efficient, so that producing that 0.66HP would require 1.3HP from the engine.

Not sure how much power is required to drive a mechanical water pump and fan unit but I'd be surprised if it was less than that, Doc suggested 10HP.

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Last Edit: 29 Nov 2014 06:05 by dandjcr.
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29 Nov 2014 05:27 #18 by Peter_n_Margaret
Peter_n_Margaret replied the topic: Electric Fan
I thought an aircon was in the order of 5HP?

Cheers, Peter.
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29 Nov 2014 05:44 - 29 Nov 2014 06:46 #19 by dandjcr
dandjcr replied the topic: Electric Fan

Peter_n_Margaret wrote: I thought an aircon was in the order of 5HP?


Peter, as far as I can ascertain, that's about right.

Wikipedia says "In a modern automobile, the A/C system will use around 4 horsepower (3 kW) of the engine's power, thus increasing fuel consumption of the vehicle".

This report on a/c in vehicles says "The air conditioning system is the single largest auxiliary load on a vehicle by nearly an order of magnitude".

Which is why a/c compressor belts need to be so tight, they're transferring a lot of power, constantly. Compressors are not very efficient (around 20%) so 80% of that energy is converted into heat, which must then be dissipated in all the condensers and fans (which take more power). Turbo intercoolers do the same thing.

By comparison, an 80A alternator at full load and 50% efficiency requires 3HP (80A*13.8V*50%/746W=2.96HP) but they are seldom operating at full power. 1.1KW is a lot of electrical power to be using.

I sometimes turn off the a/c when climbing a steep hill, partly to gain a bit more power and partly to keep the water temperature in check.

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Last Edit: 29 Nov 2014 06:46 by dandjcr.

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29 Nov 2014 09:01 - 29 Nov 2014 09:22 #20 by Dean and Kaye Howells
Dean and Kaye Howells replied the topic: Electric Fan
Thanks David for the info and links, it makes for interesting and informative reading.

I presume you've used the F350 dimensioning figures in your example as this would be comparable to the OKA ? I thought so as well until I looked deeper and found that Davis Craig recommend the same fan setup for a Honda Prelude.

Well, this begs the question,................... "How is it that a small 2 litre Sports Coupe has the same cooling requirements as a 6.2 litre heavy duty 4WD".

Clearly it does not. What Davis Craig say in their 'What fan do I need' advice is ......"Where radiator is rectangular there may be no choice but to fit two smaller fans; choose the largest that can be accommodated in space available."

I take this to mean that the maximum surface area of the radiator should covered (by fan) as this will give optimal cooling efficiency and lessen the potential formation of 'hot spots' in the radiator. From a design point of view this makes good sense.

The OKA LT radiator core measures approx. 800mm X 450mm so using Davis Craig recommendations 2 X 'Thermatic fan - Heavy Duty DSCL16' are what's required.

For these the current draw is 19 amps each. So with 10 amps for the electric water pump makes a total of 48 additional amps the electrical system needs to deliver. Not an insignificant amount.

In power terms this equates to 13.7 volt X 48 amps = 658 watts. Taking into account a 50% efficiency rating for the alternator this equates to 1.75 HP of engine power.

From a cost view point around $900 all up or a bit more if you get the alloy housed pump as opposed to the plastic one. Add to this another $300 or $400 for a decent 130 amp alternator for which a dual V belt drive would be a good idea at $?. It is possible that a battery upgrade could be needed, especially in a single vehicle battery setup at $?. A spare pump at around $300 (as suggested by DOC) plus fitting it all makes for a reasonably expensive cooling solution.

A couple of technical points here for anyone considering this modification.

From the photos it looks like Davis Craig mount the fans directly to the radiator core with long bolts and large washers to pull up against the radiator core. I'd recommend against this as if/when the nuts loosen off the rubbing of these bolts, washers or fan shroud on the radiator tubes can cause them to fail. It is a much better idea to mount the fans on separate bars across the front/rear of the radiator.

On another note, DOC's suggestion of "throwing away the thermostat" might be OK for a Chev V8 (about which I claim no expertise what so ever) but to do so on the Perkins engine with its bypass thermostat system could very easily result in it serious overheating and failure. Please don't do so without fully understanding how this bypass system works and what the effect of removing the management of water flow direction is. It may be possible to solve this issue with a simple 'baffle' in the thermostat housing or other solution but I haven't looked close enough at the issue to say for sure.


Deano :)
Last Edit: 29 Nov 2014 09:22 by Dean and Kaye Howells.

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29 Nov 2014 09:11 #21 by TH
TH replied the topic: Electric Fan

Dean and Kaye Howells wrote:

TH wrote: ................................. I'd be surprised if it takes more than 2hp to circulate the system. So the electrical requiements, in theory, shouldn't be excessive.


Hi Tony, 2 HP is the equivalent of approx. 1500 watts or 125 amps on a 12 volt system. This is the theoretical 'best case' value assuming no losses in generating the 2 HP at all.

This figure represents a massive additional load on the vehicles electrical system. OKA 413 has a Bosch 1280, 12 volt 80 amp alternator fitted. This figure (125 amp) represents a more than 50% overload of its maximum rating and does not take into account any other electrical load on the system.

This is why I am concerned about stress on the vehicle electrical system when using an electric fan/pump setup.

If indeed 2 HP is a realistic figure then an alternator with a minimum rating of at least 200 amps (250 would be better) would be needed. This would require a substantial upgrade of mounting, cabling and drive (dual belts minimum) and would be quite costly. There would IMO need to be some pretty significant comparative advantages to change to a system such as this.

Deano :)


The mechanical pump is likely the most efficient method of cooling in terms of power consumption but it's hardly an efficient method of cooling. I have an intercooler in the way that takes up the entire tunnel and I need to improve the bog cooling system so I can cruise to remote summer fishing spots in comfort instead of at 1am.

Cheers, Tony
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