Re: Whats the sodium for?

["David L. Cooper" <d.cooper@ix.netcom.com>]

Can this happen in a fraction of a second?

Douglas Hurst Quebbeman wrote:

> > > >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.
> > >
> > 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?
>
> Sodium melts at 97.8 deg. C (208 deg F). So yes, I'd
> say it's definitely melting. So simple convective
> cooling is taking place. Once the sodium has melted,
> the hotter sodium rises up away from the valve face,
> carrying the heat to the valve stem, where it's then
> conducted out by the rest of the valve train. Then, as
> the sodium cools, it falls back down the valve stem
> toward the valve face, where all the heat is being
> generated.
>
> Very nice system, and I was surprised the first time
> I heard about it (this was before I understood what
> Vorsprung Durch Technik means).
> --
> -Douglas Hurst Quebbeman (dougq@iglou.com)            [Call me "Doug"]
>     QuattroClub USA# 4536              Audi International # 100024
>        74 100LS Auto, 77 100LS Auto, 84 Coupe GT, 86 5Kcstq
> "The large print giveth, and the small print taketh away."  -Tom Waits