<VV> Re: [fastvair] Fans

[ScottyGrover at aol.com]

In a message dated 8/5/2007 9:15:03 P.M. Pacific Daylight Time,  
ScottyGrover at aol.com writes:

In a  message dated 8/5/2007 7:56:19 P.M. Pacific Daylight Time,   
eschakel at earthlink.net writes:




Scotty, before you go  into the world of fan design and manufacture,  does
anyone on this  list have contemporary fan test information?

All  of the fan data  I've seen comes from ancient SAE or GM tests using  OE
configurations  on stock engines. The highest RPM listed in Bob  Helt's
Classic  Corvair is 5200. Does anyone on this list have real fan HP  losses  
at
the elevated RPM the FastVair folks tend to push? I run my engine   to 7200
now and then, and there are rumors of some of the eastern  Vairs  pushing over
8000 regularly. My cut-down LM magnesium fan has  been more  than adequate in
street driving, and no problem on the  track in 110 degree  conditions since I
added a front-mount oil  cooler. 

The estimates  I've read for losses at 6500 with a  cut-down fan range from 9
HP to 23 HP,  which is probably interpolated  from GM data or just  flat
made-up.

So, what's a new fan design  worth? If I'm losing 9 HP  at high revs, I don't
think there's any  good reason to screw around with  fans, particularly if the
whole  drive and ducting system has to be changed  to accommodate the  new
design. Now, if I'm losing 23 HP at high revs, let's  talk about a  new fan
design. We know the electric fan isn't going to get  the job  done under a
load as initially offered, and that is a great step.   

Other than that, however, we seem to be heading for the  stratosphere  again.
Anybody have data?

Eric  Schakel

_____  



Eric, 
If you search Google with the subject "fan laws", you will find out why  your 
HP requirements are reduced when you cut down the fan diameter.
I refer you to that site rather than give you the data directly because I  am 
no ME, they are.
 
Scotty from Hollyweird



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