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RE: RE: Whats the sodium for?
So, the way I read this is that Audi used sodium-filled valves on the turbo cars because the standard valves were not up to the job and SS must have been too expensive for production use?
-glen
There is an aspect of apples vs. oranges here. Valve longevity is aided by
both cooling and temperature resistance. Given a metal with sufficient
ductility, hardness, whatever for valve use, then higher temperature
resistance is better. This is generally associated with high nickel content
(SS, Nimonic 80A, ...)
For better cooling, sodium can be used to transfer heat from the valve head
to the stem, where the oil splashing about can cool it. It was my
understanding that sodium-filled valves were only partly filled, so the
sodium was cycled from head to stem as the valve moved up and down (or vice
versa).
.... Kirby (Kirby A. Smith)
2 x 1988 90q
New Hampshire USA