Viscous fan to electric

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The load on the alternator is not a problem cos the average load of a Td5 is 50A tops so an extra 35-40 is not a killer for a 120A generator, only the CFM matters and when i said 2500 minimum i meant a normal UK weather, in warmer regions where the outside temp goes often above 30*C at least 4000 is needed(that's about the viscous fan's performance)
 
sierrafery said:
The load on the alternator is not a problem cos the average load of a Td5 is 50A tops so an extra 35-40 is not a killer for a 120A generator, only the CFM matters and when i said 2500 minimum i meant a normal UK weather, in warmer regions where the outside temp goes often above 30*C at least 4000 is needed(that's about the viscous fan's performance)
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50A sounds a bit low? Heated screen 35-40A alone! Rear heated screen, another 15-20A for all the lights etc etc
 
I should have mentioned the 50A for summer off course, i thought it's obvious as we speak about thermocoupled engine cooling fans which would not kick in both or at all when heated screens are needed :cool:
 
Have you got a remap to worry about EGT? Get your gauge going before you shell out on an intercooler as a decent remap should not require one. If you have s 15p i think that has a bigger intercooler anyway
 
robhtid said:
Surely the cowel restricts airflow massively when the fans arent running.the viscous isnt coweld and surely 2x220w fans outperform the viscous
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It is a balalncing act.
I run capilliary temp gauges on my two 200s, one I fitted the 16 elec fan in front of the rad, and straight away I noticed during normal operaton the engine now ran 2 to 3 degs warmer due to air flow restriction.
The other has the fan on the rear of the rad and that one kept the same temp as before.
 
robhtid said:
No not at all its just something I've seen. I may look at duel fans with 4500cfm then set up on different stats to come on in stages.

I diddnt know there was only 3 levels. Mine is normally at the lowest then goes up to halfway when being worked in heat.

Ill get a gauge sorted for it when I get the fans!

I'm already getting an egt gauge because of you! And actually your the reason I'm getting a intercooler to bring my egts down a touch to try prolong its life!
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It isn't really a gauge, not in the same sense as older cars. Think of it as more like 3 lights:
-blue
-green
-red

Sort of thing. Therefore a large temperate range exists for each 'stage/colour'.
 
Ok thanks for that that's useful to know the temp gauge isnt very useful. I may end up with the one in the link provided. Thanks.

As for the egt temps it's not because of mapping but slightly larger tyres and towing.

I think my way arround all this is keep the viscous fan and when I fit the airtec cooler fit a alloy rad too, found some that are +30 capacaty
 
robhtid said:
Do you think 2 electric fans is no good still.
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I'm not up on the TD5, but as long as the electric fans move more air than the engine driven fan, in theory it should be ok with some caveats, (see below).
robhtid said:
I was also thinking there is basically a lump with vairbleb restriction from the fan stuck on the crank and in my previous life In making things fast the lighter crank rods etc the better. I'm not trying to make it fast but I thought it would help the engine
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Removing the fan will make no difference to the rotating mass of the engine. Maybe if it were a light weight, revvy petrol engine sure, but a large, heavy, slow turning, slow accelerating diesel, no there's no noticeable difference removing 3Lb of fan.

The air the fan moves will cause more drag than it's rotating mass.
robhtid said:
I may look at duel fans with 4500cfm then set up on different stats to come on in stages
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A viscous linked engine driven fan is an efficient way to cool an engine. An engine fan is using power directly from the engine, i.e. no other losses in the system, except a bit of belt drag. Now consider an electric fan, with an equivalent air flow rate. You need to generate the energy (electrical) often from the same belt as the mechanical fan. Generation of electric creates a loss in energy conversion, then you have to feed that electric energy to the fans(more losses in the wiring), which then power electric motors in the fans (again more losses), effectively cancelling out any potential benefits to using them. The only reason to use electric fans, is to aid warm up times, when it's very cold (there's no increased airflow over the engine), or to overcome some inherent design error made by the vehicle manufacturer.

Most modern cars have electric fans, but only because radiators are now proportionately huge compared to the heat load of the engine, and almost all vehicles now have transverse engines, making engine driven fans impractical.

Me, I'd make sure the viscous coupling is working correctly, and stick with the engine driven fan. ;)
 
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robhtid said:
No not at all its just something I've seen. I may look at duel fans with 4500cfm then set up on different stats to come on in stages.
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So is that 4500cfm for just one fan, or is each fan quotes at 2250cfm ? if so putting two fans together does not increase the maximum airflow of the fans.
So if you have a fan that pushes 2250cfm in a theoretical, no resistance situation, putting two of them together will still only push 2250cfm.
What stacking can do though is help overcome resistance to the fan.
It is common practice among AC/water coolers to stack fans to help overcome the resistance of the radiator that the fans are blowing air through.

Much the same with sound, 100db sounder plus another 100db sounder doesn't make it 200db.
 
discool said:
So is that 4500cfm for just one fan, or is each fan quotes at 2250cfm ? if so putting two fans together does not increase the maximum airflow of the fans.

When side by side they are pulling there own air through the rad so the volume is
So if you have a fan that pushes 2250cfm in a theoretical, no resistance situation, putting two of them together will still only push 2250cfm.
What stacking can do though is help overcome resistance to the fan.
It is common practice among AC/water coolers to stack fans to help overcome the resistance of the radiator that the fans are blowing air through.

Much the same with sound, 100db sounder plus another 100db sounder doesn't make it 200db.
Click to expand...


I agree what you are saying and that is true if the fans are on top of each other but next to each other. They can both pull 2250cfm throuh their own section of radiator
 
A bucket of water... put one 5lpm pump in it

A second bucket of water the same size...put 2 5lpm pumps in it

Wich one empties first?

Swap the water for air and the pumps for fans
 
I'm not doubting your knowledge as there are some very clever people about and I'm sure you are one of them but I would like to understand this.

Are you saying there is no improvement in cooling using two fans instead of one as there is no increase in airflow?
 
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