[s-cars] Fans on the dyno

[QSHIPQ at aol.com]

I don't think it was a measureable part of it at all Mark!  You can  stop 
that fan with your hand in a glove when the VC is locked up, and it will  slip on 
the belt.  I doubt it's even 2 hp (see math below). 
 
The reason for VC fans is to keep the load off the electrical system.   As a 
rule, engine power to drive a fan is more efficient than electrical  power.  
The narrower the pitch of the fan (and S shaped fans are less  efficient at 
moving air) the less load it will have on the  motor/engine.   The smaller fan 
blade depth, the less efficient  it will be as well.  But, mechanical fans also 
tend to move more air for a  given rpm, because they don't overload the motor. 
 For more on this look at  flow vs load draw on Spa electric fan 
specification sheets.
 
Prior to the v8 then Scar, cooling was using a 70amp driven electric 7  blade 
fan in the 5000/200.  12 x 70 = 840watt fan.  That sucks up a  lot of 
alternator capacity.  Add in the S car aux fan 300watter, you have  potentially 
1140watts of draw using that same app. 1140/12 = 95 amp draw on a  110amp alt, no 
other load counted!
 
Now, if we know that 1 hp = 750watts, then that old 840 watt fan is  1.12hp,  
Mark, call the one in the S car double the old 200 fan,  at 2 horsepower, 
it's the equivelent of a 1600watt fan.  At that, it  shouldn't need the 300w aux 
fan.  No, I rather suspect that the stock fan  is less than 1hp, as Golledge 
notes, it's not even a driven part (it's off the  back of the belt)
 
Those of us familiar with the older monster 7 blade fans, would call the S  
car VC driven fan a joke in comparison to the old 200 7 blade style.
 
Continuing the argument, for 40hp = 30,000 watt fan.  Saying that  the S car 
mechanical fan is 30 times the air of the old 840 watt audi fan, seems  a bit 
unreal to me.
 
I have a lot of my Landcruiser library full of information on  switching from 
the monster helicopter blade to electrics, including research  into the 
electro coupling mechanical fan.   I have yet to find a  electric setup I'm 
comfortable with to equal the cooling potential, and would  rather see the 
electro-mechanical coupling conversion come into play, it is the  future of all 
automotive and truck fans IMO.
 
Scott Justusson
In a message dated 5/11/2007 7:28:18 P.M. Central Standard Time,  
StrangConst at rogers.com writes:

Like I  said later, mine was seized so that would actually suck the power if 
it need  the cooling or not.
I did  measure a 40 HP gain, I cannot say 100% it  was due to just the fan, 
but I really have to believe that was a large portion  of it

Mark 


 



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