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Old 07-01-2015, 04:10 PM
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crystalworks crystalworks is offline
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Quote:
Originally Posted by trader4 View Post
Then someone should be able to explain the physics of why this
little 15" fan can require so much power to operate where all
similar size fans, doing similar work, don't require anywhere near
that much power. What is so special?

Also note that a dyno test is without the car moving. With
the car moving air is being rammed into the fan, which would
substantially reduce the power needed. At highway speed there
is enough air that the fan probably isn't needed at all. And
was the test done with the electric fan running or off?
Dyno was done with the fan off of course. Leaving it on creates a fairly large load on the alternator and will cause HP loss. That's one of the points of going with an electric over a parasitic. You don't have to run it all the time... as you said like at highway speeds and such. Less wear and tear on the water pump snout/bearing is a nice bonus as well.

The comparisons you are trying to make with other application type fans are not going to work... and I wish I were a mechanical engineer to explain technically why. But trying to compare say a 5hp fan with a dedicated 5hp engine on it to a 120hp car engine with a fan on the front of it is just not an apples to apples comparison. Rotational mass, condition of fan clutch, etc, etc... will all come into play.

bcredliner... I believe there is an electric water pump available for the M54. At least I THINK I remember reading something about them on e46fanatics.
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