RE: Whats the sodium for?

[Robert Myers <rmyers@inetone.net>]

Sodium melts below 100 degrees C.  It will definitely be liquid at valve
stem operating temperatures.

However, in a tube like a valve stem, whether or not the Na is liquid will
have very little to do with its ability to help cooling.  It is a fantastic
conductor, both electrically and thermally - far better than steel.  It is
this conductivity which helps remove heat from the hot end of the valve.
Convective circulation of molten Na in the narrow tube with its built in
restriction to flow is possibly a help but I doubt it is all that big an
effect.

At 08:09 AM 6/1/98 -0400, you wrote:
>
>I'm not sure that sodium reaches a liquid state at the temperatures
encountered in even a turbo-charged internal combustion engine. Anyone got
another theory?
>
>-glen
>
>
>>In the turbo head the valves have sodium in 'em.  How does this allow
>>you to run more boost?  Does it cool the valve better???
>
>As the valve opens and closes the liquid sodium moves inside the valve,
>taking the heat away from the tip and transfering it to the well cooled
>stem. Liquid sodium is an excellent heat conductor - it is used on some
>nuclear sumbarines for cooling reactors.
>
>
>Aleksander Mierzwa
>Warsaw, Poland
>mailto:alex@matrix.com.pl
>87 Audi 5000CS turbo (mine)
>88 Renault Medallion wagon (mom's)
>91 mountain bike (just in case both cars broke at the same time :-)
>
>
>
>
>
___
   Bob
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