Hollow-stemmed valves

[Route666]

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!

 

[SoCalCruising]

This combo was written up in MMFF in '04 or '05 by David Vizard. He acheived the kind of gains you describe. The valves are relatively expensive, but much less than Ti, and the beehives have their detractors. I spent a lot of time looking into beehives. The top shop in my area advised against them because there is no damper or second spring - if one breaks, the valve goes directly into the cylinder. He had seen a few go that way when coupled with big cams. On smaller cams, it would be much less of a concern. I woulnd up going with a cam/spring combo from Ed Curtis. It should be good to 6500RPM, which is all I was looking for.

 

[rbohm]

sodium valves, and hollow stem valves have their place in a race engines. you can even use them in hot street engines as well, but for the most part they are not needed, and would be a waste of money, with perhaps the exception of sodium filled exhaust valves in a medium or heavy duty application. and that only to help keep exhaust valve temps in line under heard use.

the way that these valves are made, leaves them particularly vulnerable to breaking if the friction weld has a flaw in it.

 

[Route666]

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.

 

[1320stang]

Some of the old 427's had sodium filled valves, they had problems with the heads poping off. Part of this I think is due to age, and maybe technology of the 60's, but I recall that sodium reacts with the valve material and eats it from the inside out over time.

 

[Route666]

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).