Engine Fans.

Iamzod

Iamzod

Iamzod

Soldato
Joined
7 Dec 2002
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UK
How much power do Mechanical/Viscous cooling fans eat as opposed to fully electric ones?

Same question really with fuel consumption, i let out a breif list of swear words half way through refuelling the other afternoon when i realised Normal Super unleaded had shot up to £1.01 a litre

I know its going to vary from car to car, but are we talking an average of something totally irrelevant like 1- 2 BHP?
 
I saw a diagram a while ago which showed bhp loss over an engine and it said it was about 5-7bhp for the viscous cupled fan. Whether its believeable or not is a different matter but considering it does take its drive from a pulley driven from the crank there should be some parasitic losses just like a supercharger so it isnt unrealistic.
 
Yes, viscous fans do draw a few HP away from your total output. However, so does a sodding 'gert electric fan, which loads up the alternator quite a bit! :p BUT - when it's not on, you don't have the load (or the reason why I run them) the irritating whooshing noise :)

And, at the end of the day, a few HP can't be felt on the road. Worth it for the MPG more than anything, mine went up by a phenomenal 2mpg :p

One of the Sprints I had couldn't take the load when the electric fan kicked in and would stall, which was quite amusing :( More down to 70s electronics than anything mind...
 
No - I mean just the wooshing that the blades make at high RPMs. Sorry, no idea why I said 'whir' :D ..most viscous fans tend to rattle when they're on the way out anyway. Kept thinking my waterpump was going.....
 
No, no, I mean when you rev it hard and you get the "THWIRRrrrrr"

:p

Ha, I'm certainly not being very coherent today. I do apologies :D

You do get fan noise from it as you drive along anyway, the viscous action(certainly in mine) isn't there to stop the fan rotating, merely slow it down at high RPMs to prevent over cooling. So you still get a pronounced whir as you drive along :)
 
Lashout_UK said:
No - I mean just the wooshing that the blades make at high RPMs. Sorry, no idea why I said 'whir' :D ..most viscous fans tend to rattle when they're on the way out anyway. Kept thinking my waterpump was going.....
Click to expand...
Mines so on the way out it bangs :s . What happens when they finally die? It always slips or never slips?
 
Erm...I can't say for other manufacturers but the viscous fans on mine...

They tend to try to escape - either by going "BANG" and hitting the bonnet, making a nice dent, or by going "THRRRRR", unscrewing themselves and chewing their way through the radiator! A messy state of affairs either way.

:o
 
I'm going to be removing the viscous fan from my CA18DET when it goes in the Anglia, can fit a much slimmer electric fan, as space will definitely be at a premium at the front of the engine bay! ;)

Any BHP increases will quite probably be noticed in something with >170bhp and weighs <900kg :)
 
Hmm. Could be interesting. Things is it's a right faf to sort out and I've got a new engine on the way anyway. It's lasted this long, I'm sure it'll manage...
 
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