<VV> [fastvair] Fwd: fans and such

[jvhroberts at aol.com]

 Ask the question 'why?'. Slip isn't all that bad a thing for a stock fan. But back to your question...

In a word, no. Toothed drive belts, be they Gilmer or the newer and preferred PowerGrip HTD  or GT2 style have extremely rigid and non extensible fiberglass cords, meaning, a twist would put all the tension to the outer edges of the belt. Futhermore, for this to work, the belt would have to be very narrow, and those styles generally don't have particularly good power handling capability. And the lack of slip eliminates the 'safety valve'. 

Flat style belts, used as serpentine belts on today's cars, are more forgiving. By not being synchronous belts, they can slip. Also, with the grooves running parallel to the belt travel direction, they are FAR more self guiding than a toothed belt. And a lot of these are available in narrow flavors. Also, their construction, contrary to some rumors, is not a duplicate of a timing belt. They can twist, but not sure they can twist as much as a Corvair drive belt does. 

However, serpentine belts do have one advantage: They can drive from both sides. This makes driving the fan opposite in direction from the crank a very realistic possibility should one choose a fan with a horizontal axis. For a fan with a vertical axis, who knows? A pair of idler pulleys near the front of the engine may give a similar option. 

But back to my first question. In any pursuit of an engineering solution you need to ask 'What problem are we solving'?  Is it more cooling? What are the options? Adding more power to the stock fan is a dead end. It already sucks up too much HP for what it delivers. Is it to prevent overloading the drive at high RPM? Well, a slipping belt does that! Or a viscous clutch, or... 
But if the fan was truly an efficient design, there may not be a drive problem whatsoever! Not to beat a dead horse, but 911 fans move more air, develop more pressure, and consume a LOT less HP than the Corvair unit. And in that, I believe, is where the right approach lays. 

 

John Roberts
 

 

-----Original Message-----
From: scottygrover at aol.com
To: virtualvairs at corvair.org; fastvair at yahoogroups.com
Sent: Sun, Mar 28, 2010 10:55 am
Subject: [fastvair] Fwd: fans and such


  
                  


____________________________________
 From: ScottyGrover at aol.com
To: mfrancis at wi.rr.com
Sent: 3/25/2010  1:08:26 P.M. Pacific Daylight Time
Subj: Re: fans and such

I'm wondering whether toothed belts can be made to go over toothed  pulleys 
with a bend in the belt similar to the stock system. If they can, and  if 
belts can be found that will handle the power needed to drive the fan to  
higher RPM's, it might help with the cooling problem. At the very least, it  
would prove or disprove the theory that the limit to CFM's delivered is the  
slip in the belts when the belt can no longer handle the HP needed to drive  
the fan at higher RPM's
 
Scotty

[Non-text portions of this message have been removed]


    
         
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