ifloochies
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Have you considered the current draw of those fans when they kick in and the load it would put on the alternator?
Viscous fan to electric
- Thread starter robhtid
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sierrafery
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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)
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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
sierrafery
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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 
ronsealdeath
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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
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.
300bhp/ton
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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
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
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).
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.
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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ronsealdeath
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Does the viscous fan also aid air flow around the wider engine bay i wonder? Helping disperse heat from manifold/turbo?
Of course. A turbo is air and oil cooled, although some are also water cooled too.
Google engine heat soak.
discool
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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.
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
discool
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I assumed that the fans would be side by side as they are in vehicles
discool
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No it isn't, the air flow is still the same which is the capacity of the fan. You confused with flow and pressure.If they are side by side then they do have a joint airflow of 4500
discool
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You have mistake with the quantity of the water and air there's a difference.
If u have an HNC qualification, like me you should see it instantly.
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?
Are you saying there is no improvement in cooling using two fans instead of one as there is no increase in airflow?
