Replacing the clutch fan with a thermo fan
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raywise
Member
I've often thought of this myself and if it would be worth doing. In one of the 4wd mags recently they found that you gain approx 1/4 HP by going thermo fans, and it was definatley not worth doing if you want to do this solely to get back some lost HP.
Modern viscous hubs work fine anyway.
Modern viscous hubs work fine anyway.
the big problem is that most electric fans cannot match a mechanical for air flow. for a vehicle thats crawls up hills at low speed that extremely important.
brendan
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not knowing the flow rates of the engine fan. i will say thermo fans draws max air flow at any given rpm. engine fan is related to engine speed
D
Dave
Guest
Yes it would but dont forget when the engine heats up the gel inside the fan coupling gets thicker and makes the fan work.
Normally it is almost free spinning.
Dave.
Normally it is almost free spinning.
Dave.
that makes almost no difference. when your at max heat your doing more than enough rpm to run the mechanical fan.
the only good thing with electric is it can keep going after you have slowed down or stopped, which gets rid of the heat stored in the system. which may make it ok for small hills etc.
but at the end of the day, without good airflow you can overheat the motor.
bods
Member
as most of these type topics it's going to be more what people prefer as to what is necessarily better.
think about it this way, ford and holden both used viscous hub fans for years, but mid 90's changed over to thermo fans. the newer models obviously produce more power than the older ones so if cooling with thermo fans as opposed to clutch fans was an issue i can't see them having changed over.
i don't know why all new cars don't come with thermo fans these days. the main advantage i can see in a 4wd is water crossings, you can simply hop out and pull the relay or the plug and not worry about having to pull the drive belts off or having the fan decide to eat the radiator if you happen to stop mid crossing.
a properly designed and shrouded thermo fan would probably be more efficient than a clutch fan. the biggest problem with thermo fans is that most of the people that don't like them have either used them or know someone who has, without a shroud, in which case a clutch fan would be no better anyway...
think about it this way, ford and holden both used viscous hub fans for years, but mid 90's changed over to thermo fans. the newer models obviously produce more power than the older ones so if cooling with thermo fans as opposed to clutch fans was an issue i can't see them having changed over.
i don't know why all new cars don't come with thermo fans these days. the main advantage i can see in a 4wd is water crossings, you can simply hop out and pull the relay or the plug and not worry about having to pull the drive belts off or having the fan decide to eat the radiator if you happen to stop mid crossing.
a properly designed and shrouded thermo fan would probably be more efficient than a clutch fan. the biggest problem with thermo fans is that most of the people that don't like them have either used them or know someone who has, without a shroud, in which case a clutch fan would be no better anyway...
i have to disagree with bods.
even the aftermarket electric fan companies concede that mechanical fans are better for slow moving high load vehicles ie tractor, truck, 4x4 etc.
most car manufactures don't use mechanical as electrics are more 'efficient'. i mean efficient as in they turn off when not required so they don't cost any power, economy or emissions when they are not in use. all 3 are things car companies have really chased after. especially when its in a car that rarely goes slow enough to warrant having a mechanical fan.
in a ute or 4x4 thats more than likely will be going slow, it makes more sense to use a mechanical fan as they are better at pulling air through.
even the aftermarket electric fan companies concede that mechanical fans are better for slow moving high load vehicles ie tractor, truck, 4x4 etc.
most car manufactures don't use mechanical as electrics are more 'efficient'. i mean efficient as in they turn off when not required so they don't cost any power, economy or emissions when they are not in use. all 3 are things car companies have really chased after. especially when its in a car that rarely goes slow enough to warrant having a mechanical fan.
in a ute or 4x4 thats more than likely will be going slow, it makes more sense to use a mechanical fan as they are better at pulling air through.
