[s-cars] Fans on the dyno

[QSHIPQ at aol.com]

Safety first!  I've stopped a lot of fans with gloves Mark, and the S  car 
one is the easiest (you should see the blade on the landcruiser!).  I  don't 
advocate it, just indicating that 40hp wouldn't allow me to stop that fan  with a 
2x4.
 
Usually a mechanical fan is more efficient at higher engine rpm (electrics  
advantage is that it's not tied to engine rpm), and not so efficient at lower  
rpm, since fixed pitch blades have an "optimal" rpm.  Higher fan rpm  does 
mean higher load, on both the mechanical and the electric (again see Spa  specs). 
 This is a function of the work output of drawing air thru the  radiator (or 
in the case of my supercharged landcruser at Steamboat, a function  of drawing 
the blades thru the radiator core... doh!).
 
That said, I think if you compare full load of the mechanical fan in the S  
car with a equivalent electric fan, the alt at 100% will draw more power.   If 
that wasn't the case, then the mechanical pulley for the fan in the S  car 
should be on the front of the ribbed belt, not looped to the back.
 
Again, I got a beer says taking the mechanical fan off the pulley of an S  
car, won't yield any measureable gain on the dyno, because I doubt it draws 1 hp 
 fully locked up.
 
My .02
 
Scott Justusson
Electric fans a plenty 
1 landcruiser mechanical fan modded with the aid of rocket scientist Dave  
Lawson
 
In a message dated 5/12/2007 7:41:01 A.M. Central Standard Time,  
StrangConst at rogers.com writes:

I will not argue with your math, not one bit.
But I would not be trying to stop my , or anyone else's seized VC fan.  Not 
with a glozed hand, not with a block of wood.
I don't remember what other changes where made between run's but it  wasn't 
significant.
I think I just removed the fan and adjusted the water injection.
 
Maybe my only comments to your deductions is that a mechanical fan's  power 
requirements are a function of it's RPM. Higher RPM = higher load ? No  ?
 
Just how many HP does it take to turn the alternator shaft when the load  on 
it is 95% ?
 
Mark



 



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