Another Drew

Since I'm so bored waited for my S4, anyone know what's behind those sodium cooled valves?
Drew

I sure hope that high sodium levels don't cause high blood pressure and cause the valves to clog.

Jim De Arras

As I understand it, the valve stem, and maybe the body too, is hollow, and filled with Sodium, which is susposed to carry the valve heat out the stem faster and keep the valve itself cooler.

Jim

Jim De Arras

Sodium-cooled valve: An exhaust valve with a hollow stem that is partially filled with metallic sodium. When the valve gets hot enough (138°C), the sodium melts and moves up and down in the valve stem. The sodium absorbs heat from the hot valve head and carries it away to the outer part of the stem and then into the valve guide in the cylinder head and next to the cylinder head itself. This circulation cools the valve head and thus the valve is allowed to run at a lower temperature.

Another Drew

For one of my senior level classes back in undergrad, I worked with internal combustion engine designing (piston design and pre-chamber combustion) and that sodium cooled valves sounds really neat. Where did you get this info and do you know of any other cars that have these?

Drew

Kevin L

If the sodium finds a way out of the valve, it is sure to poison the cataytist in the convertor!

Christophe

It is not that new for sport engines.
The exhaust valves are filled in with a sodium component inside , which acts like a cooler for the valves.
I remember the first Alfa Romeo of my father was already equipped with this feature (in 1976).
All Ferrari or BMW Alpina have that feature since ages.
Notwithstanding, the S4 has an extremely well shaped engine. But it is mainly due to electronic components.

have Sodium filled valves

All turbocharged Audis since the late seventies

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I forget which manufacturer was using it, but it's old anyway. Few really new technologies have been invented in the recent years. The one that stands most to mind is the computer (ECU).

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