<VV> RE: Lower shrouds

[JVHRoberts at aol.com]

A couple of things:
1. Corvair engines are NOT designed like aircraft engines.
2. Corvair engines in cars are not exposed to the same condtions as  aircraft 
engines. 
3. Shock cooling a Corvair engine is nearly impossible, and I have never  
heard of ANYONE whose engine has suffered thusly. 
4. Corvair engines have marginal cooling at best, I have never come across  
one that has suffered from overcooling under anything resembling ordinary  
driving conditions, even in zero degree weather. Slow to warm up, sometimes, but  
steady state low temperatures while driving, never. 
 
In a message dated 7/2/2007 9:59:25 AM Eastern Daylight Time,  
corvair at fnader.com writes:

If  you're measuring head temps in the stock sender location, that 
reading is  influenced by the exhaust temps and is something like 75-100 
degrees  hotter than the actual head temps (measured traditionally at the 
spark  plug). In my fully laden 110/PG VW Westy, I can drive the head 
temps  (measured at the plug) to 300 or so (roughly equivalent to your 
400 at the  stock sender location) by lugging it down in top gear and 
full throttle up  long hills;  well within the specs and the typical 
temps for  air-cooled engines. The alternative measurement location is 
why Corvair  temp specs seem so high to those well-versed in other 
air-cooled  engines.

While the engine will quickly cool (either by shifting into  Low or by 
cresting the hill) I don't think it's fast enough or far enough  to be 
considered "shock cooling"... whether with or without bottom  shrouds.

Bill

Pitts10ch at aol.com wrote:

>I live in CT  and it is hilly around here of course.  I see 300 degrees  
most  
>of the time when I am zipping around the curvy hills at power.  I  do  see 
it 
>drop when on the back side of a hill about 50 degrees  over a minute or  
two.  
>With the shrouds on, I see 400 - 410  on the highway.  That seems  hot to me 
but 
>I come from  aircraft engines and 400 + is pretty warm on that  front.  I 
can  
>see that I could be shock cooling on the backside of a hill   which causes 
>cracking in aircraft engines between the spark plug hole  and the  exhaust 
valve.  
>Anyway, I think IL is probably a  really safe bet on  the shroudless and I 
am 
>probably on the  ragged edge when going down a long  hill.  Has anybody ever 
 
>heard of cracking jugs on these beasts?  If  that is not the  concern what 
other 
>negative effects could over cooling   have?  
> 
>Fingers worn out,
> 
>Chris  H.
>'66 140/4 


 



************************************** See what's free at http://www.aol.com.