[Vwdiesel] Turbo dreams

[Libbybapa at wmconnect.com]

My understanding of sodium-filled valves is that the sodium melts at a low 
temperature.  The liquid flows around inside valves transferring more heat to 
surrounding parts of engine (guides, lifters, etc...), rather than just to the 
seats.
I know a machinist who doesn't like them, says that they are weaker due to 
being hollw.  Any additional thoughts?
Andrew