<VV> Fan belt tension (Clarification)

[RoboMan91324 at aol.com]

Mark,
 
Yes, the engine's growth should be greater than the belt's growth.   
However, if you look at the coefficients and expected temperature rise, the  
growth is not huge.  You might expect 0.1 - 0.15 of an Inch growth from the  
crankshaft pulley to the fan pulley.  Those numbers are off the top of  my head. 
 This is not that much if you have the tension properly adjusted  but it 
would contribute to a problem if the tension started out too tight when  cold. 
 Keep in mind that the crankshaft pulley will get hot with a  resulting 
increase in friction.  The alt/gen pulley also gets fairly  hot.  This means 
that any slippage the system requires is more likely to  occur at the fan 
pulley which stays relatively cool in the cooling air slip  stream.
 
The fact that the belt has little heat gain means that it will not grow in  
length much.  However, there will be some heat gain and growth.  I am  not 
sure how much.  Keep in mind that the belt's growth is held in  check 
lengthwise by the fibers but the rubber/polymer content will still plump  up more 
than the direct thermal coefficient of expansion would normally  indicate.  
Also, even a small rise in temperature of the  rubber/polymer in the belt 
will cause a noticeable rise in friction.   Both of these effects contribute 
to the problem.
 
Doc
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 
In a message dated 4/13/2012 9:00:29 A.M. Pacific Daylight Time,  
virtualvairs-request at corvair.org writes:

Message:  1
Date: Fri, 13 Apr 2012 06:29:48 -0700
From: Mark Durham  <62vair at gmail.com>
Subject: Re: <VV> Fan belt tension  (Clarification)
To: "RoboMan91324 at aol.com"  <RoboMan91324 at aol.com>,
"virtualvairs at corvair.org"  <virtualvairs at corvair.org>,
"cmckinley313 at verizon.net"  <cmckinley313 at verizon.net>
Message-ID:  <-7658543937085229929 at unknownmsgid>
Content-Type: text/plain;  charset=ISO-8859-1

So Doc, first thanks for the exacting engineering  briefing. Can we then 
summarize by saying the engine will grow more than the  belt and the belt will 
tighten up some as the engine reaches operating  temperature, not so much 
from the belt getting hot, but from the engine's  expansion?
Mark Durham