<VV> Eelco Aluminum Exhaust Manifold

[JVHRoberts at aol.com]

Ever see the exhaust system on a turbo Corvair after a hard run? The  turbine 
housing is glowing... That's well over 1200 F. 
 
In a message dated 8/4/2007 4:28:16 PM Eastern Daylight Time,  
hmlinc at sbcglobal.net writes:

Hi  Crawford,

Aluminum becomes a liquid at 1220F.  I don't know the  temp of our exhaust 
and I'm sure it varies to some degree from car to car  and HP levels as well. 
I suspect we are talking something above 600F -  maybe in the 600 to 700+ 
range.  While the aluminum may not become  liquid at that point, it certainly 
will soften to at least some  extent.  Over time and repeated use it is 
likely that aluminum  exhaust manifolds will begin to show some sag and 
potentially loose at  least a portion of the sealing capacity at the head.

Now, you mentioned  head temps earlier in comparison to exhaust valve temps. 
I simply want to  ask, have you never had an engine apart where the head 
gaskets have left  an impression in the head?  I've seen more that one 
(probably  overheated head) where an obvious lip has been left in the head 
and it is  very obvious upon removal of the gasket.  Now, the head did not 
melt  down to molten - but it also did not completely retain it's original  
shape.  Would something similar happen with Aluminum logs?

I  can see their use in specific applications - like short races.  I really  
doubt they would hold up in the long run on everyday driven vehicles -  
especially where the car is driven long distances with only fill up stops,  
like on the way to a convention.

Now, Smitty is going to tell me to  "prove it", but I don't want to.  <GRIN> 
I admit right now that  these comments are speculative in nature, but based 
on past  observations.

Later, JR


 



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