Hollow-stemmed valves

Anyone heard of, thought about, or used hollow-stemmed or hollow-stemmed, Sodium-filled valves?

I think if you combine them with beehive springs, and the smaller retainer that comes along with them, even in moly, not Titanium, you'll have less valvetrain mass than by using conventional double or triple springs, and Ti retainers AND valves.

Plus you'll have the longer lasting stainless valves and moly retainers.

Plus you'll have less spring poundage sapping power.

And better spring resonance dampening, leading to more potential rpm.


If you use less poundage on the spring, the strength of the two-piece, hollow valve will be less of an issue. If you combine it with a cam that isn't overly agressive, I'm thinking it'd be a decent setup.

I worked out that over standard dual springs, stainless valves and moly retainers you would save, at 6500rpm, 80lb of mass from moving around in the valvetrain EVERY SECOND.

I'm wondering why, like beehives, I haven't heard much of them. Is it a strength issue?

Looking forward to your input!

Thanks for the input. I get all excited when I read about something new to me that makes something lighter or stronger, etc.

I read further about the filled ones, and they're filled with a soduim AND potassium compound. One reacts violently in water and the other does so in just air, so lets put them in the hottest place imaginable - in the stems of the exhaust valve lol.


One last query - something to think about - Do they seal the hollow valves in a vacuum? If they go so far as to make them hollow, surely to do it properly you'd think they'd try and get a vacuum in there.

Yeh I can imagine it eating the valve away. It sounds like one of those race only frequent replacement things like Titanium valves (because they or the soft valve seats you use for them wear quick).