Has anyone dyno'd with the stock fan vs an efan?
#1
Rotary Freak
Thread Starter
Has anyone dyno'd with the stock fan vs an efan?
There was a thread a while back discussing efan drag vs mechanical fan drag. The general conclusion seemed to be that the efan would take just as much power to turn, and would be dragging the alternator as much or more than the stock fan.
I've spent the past few days working on my stock fan (bad clutches on it, and then a bad replacement clutch - third one seems to be working). It seems to me that at high RPM, that fan is going to draw a LOT of power. Even with the clutch slipping as designed, there's still going to be an awful lot of power drained by that fan spinning. And the faster the engine spins, the more power is going to be taken (either spinning the fan or slipping the clutch).
An efan, on the other hand, is going to draw a constant amount of power. As the engine speed goes up, this drain will be less and less, percentagewise.
So, to answer the question, has anyone tried running a dyno with the stock fan, and then again with it removed? If nobody's actually tried this, I may have to do some experiments and see if I can generate some numbers.
-=Russ=-
I've spent the past few days working on my stock fan (bad clutches on it, and then a bad replacement clutch - third one seems to be working). It seems to me that at high RPM, that fan is going to draw a LOT of power. Even with the clutch slipping as designed, there's still going to be an awful lot of power drained by that fan spinning. And the faster the engine spins, the more power is going to be taken (either spinning the fan or slipping the clutch).
An efan, on the other hand, is going to draw a constant amount of power. As the engine speed goes up, this drain will be less and less, percentagewise.
So, to answer the question, has anyone tried running a dyno with the stock fan, and then again with it removed? If nobody's actually tried this, I may have to do some experiments and see if I can generate some numbers.
-=Russ=-
#2
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I've got an electric fan that I installed with a simple toggle switch. I only have to turn it on if I'm going slower than 15-25 mph for more than a minute or two. Any speed over that and the air passing through takes care of the cooling. So my fan doesn't take any power to turn at all 99% of the time.
#3
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Originally Posted by Syonyk
It seems to me that at high RPM, that fan is going to draw a LOT of power .Even with the clutch slipping as designed, there's still going to be an awful lot of power drained by that fan spinning.
And the faster the engine spins, the more power is going to be taken (either spinning the fan or slipping the clutch).
Originally Posted by fc3skid
I've got an electric fan that I installed with a simple toggle switch.
Last edited by NZConvertible; 07-23-04 at 05:51 AM.
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I've read in varoius places that different mechanical fans pull 5-15 HP.
Ours only pull hard when the radiator heat activates the fan clutch.
An E-fan should work the same - no worries.
For an E-fan to move the same amount of air, they need to draw approximately the same power.
Most don't move as much air, so yes, they don't use quite as much power.
If you really must count on that ~10 HP for a short (14 sec) period, Use an E-fan with a temporary cut-out switch.
Or even better, an alternator cut-out switch.
Flip it off when you pre-satge, flip it back on when you lift & slow down.
Ours only pull hard when the radiator heat activates the fan clutch.
An E-fan should work the same - no worries.
For an E-fan to move the same amount of air, they need to draw approximately the same power.
Most don't move as much air, so yes, they don't use quite as much power.
If you really must count on that ~10 HP for a short (14 sec) period, Use an E-fan with a temporary cut-out switch.
Or even better, an alternator cut-out switch.
Flip it off when you pre-satge, flip it back on when you lift & slow down.
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I have a Fiero fan that has not been installed....I plan to dynotune with the stock fan first and after I remove all emissions I will dyno with the efan........we'll see.
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#8
Rotary Freak
Thread Starter
Can you possibly try running with the stock fan & efan in the same configuration? They shouldn't collide, and even though running the stock fan without a shroud would be not exactly the same as running it in the shroud, it should be close enough to see if it makes a difference.
-=Russ=-
-=Russ=-
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Originally Posted by NZConvertible
That's asking for a melted engine. The chances of you forgetting to turn it on one day are too high. When one overheat can trash the engine, why risk it? It's not like thermoswitches are expensive.
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