Sodium Filled Valve Stems. Why?
 

Dumb question I guess, but why do engine manufacturers make
valve stems that are filled with sodium (I think only exhaust
valves are sodium filled). Is it a heat expansion issue?

Thanks.

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Artemia Salina wrote:

Dumb question I guess, but why do engine manufacturers make
valve stems that are filled with sodium (I think only exhaust
valves are sodium filled). Is it a heat expansion issue?

Thanks.

Better heat conductivity aids in transferring the heat away from the
valve head.

So I was taught during my time at trade school, regarding aero engines.

Cheers
Trevor Jones

On Sun, 06 Mar 2005 15:48:35 -0500, Artemia Salina
wrote:

Dumb question I guess, but why do engine manufacturers make
valve stems that are filled with sodium (I think only exhaust
valves are sodium filled). Is it a heat expansion issue?

Heat transfer and dissipation.

"Trevor Jones" wrote in message
...
Artemia Salina wrote:

Dumb question I guess, but why do engine manufacturers make
valve stems that are filled with sodium (I think only exhaust
valves are sodium filled). Is it a heat expansion issue?

Thanks.

Better heat conductivity aids in transferring the heat away from the
valve head.

Curious that aluminum and copper both have a much higher thermal
conductivity than sodium
http://web.mit.edu/3.091/www/pt/pert14.html

But I have a feeling that the relatively low melting point of sodium(371K)
with copper(1356K) has something to do with transfering heat better. I
dunno.
http://web.mit.edu/3.091/www/pt/pert12.html
the sodium would be a liquid at internal engine temperatures.

Lawrence L'Hote wrote:
"Trevor Jones" wrote in message
...

Artemia Salina wrote:

Dumb question I guess, but why do engine manufacturers make
valve stems that are filled with sodium (I think only exhaust
valves are sodium filled). Is it a heat expansion issue?

Thanks.

Better heat conductivity aids in transferring the heat away from the
valve head.


Curious that aluminum and copper both have a much higher thermal
conductivity than sodium
http://web.mit.edu/3.091/www/pt/pert14.html

But I have a feeling that the relatively low melting point of sodium(371K)
with copper(1356K) has something to do with transfering heat better. I
dunno.
http://web.mit.edu/3.091/www/pt/pert12.html
the sodium would be a liquid at internal engine temperatures.




AFAIK sodium filled valve stems operated on the thermosyphon principle.
The sodium "absorbed" heat by evaporating at the part of the stem near
the valve head and delivered it to the other end where the sodium
condensed and the heat it gave off was transferred out through the valve
guides.

Somewhat similar to "heat pipes" but without the wick inside:

http://www.thermacore.com/hpt.htm

Jeff





--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"

The valve stems are not completely filled with sodium. As the valve heats
up, sodium vapourizes and rises up the valve stem by convection. This
carries the heat up to the top of the stem where it is dissipated by the oil
and air surrounding it. The sodium condenses and falls back to the bottom of
the valve and collects heat from the seat and continues the cycle. It
effectively forms a "heat pipe" to transfer the heat away from the seat .

Tom

"Artemia Salina" wrote in message
...
Dumb question I guess, but why do engine manufacturers make
valve stems that are filled with sodium (I think only exhaust
valves are sodium filled). Is it a heat expansion issue?

Thanks.

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0:-) 0:-) 0:-) 0:-) (-:0 (-:0 (-:0 (-:0

On Sun, 06 Mar 2005 16:39:01 -0500, Jeff Wisnia wrote:


AFAIK sodium filled valve stems operated on the thermosyphon principle.
The sodium "absorbed" heat by evaporating at the part of the stem near
the valve head and delivered it to the other end where the sodium
condensed and the heat it gave off was transferred out through the valve
guides.

Somewhat similar to "heat pipes" but without the wick inside:

http://www.thermacore.com/hpt.htm

Thanks for all the responses. As food for thought, what got me
looking at IC engine valves was the idea to remove the cam, rocker
arms, lifters, and etc. and replace it all with computer controlled
solenoid actuators. Needless to say, someone is already working on
this, with several enticing prototypes under his/her belt:

http://rbowes1.11net.com/dbowes/index.htm

That's almost exactly the idea that I'd had! Neat!


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Gravity
The liquid sodium is heavier than the vapour.

Tom
"Tom" wrote in message
...
Tom Miller wrote:

The valve stems are not completely filled with sodium. As the valve
heats
up, sodium vapourizes and rises up the valve stem by convection. This
carries the heat up to the top of the stem where it is dissipated by the
oil
and air surrounding it. The sodium condenses and falls back to the
bottom of
the valve and collects heat from the seat and continues the cycle. It
effectively forms a "heat pipe" to transfer the heat away from the seat
..

Tom

"Artemia Salina" wrote in message
...
Dumb question I guess, but why do engine manufacturers make
valve stems that are filled with sodium (I think only exhaust
valves are sodium filled). Is it a heat expansion issue?

Thanks.

--
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0:-) Artemia Salina (-:0
0:-) Surrounded by Angels (-:0
0:-) 0:-) 0:-) 0:-) (-:0 (-:0 (-:0 (-:0


This, in a reciprocating valve? What would keep the sodium
at the head end of the valve?

Tom

Tom wrote:
Tom Miller wrote:

The valve stems are not completely filled with sodium. As the valve heats
up, sodium vapourizes and rises up the valve stem by convection. This


This, in a reciprocating valve? What would keep the sodium
at the head end of the valve?
Yes, exactly. The valves are hammered with hundreds of G's every time
they slam open and shut. Convection would be totally insignificant
under such extreme acceleration. Every time the valve opens, the sodium
is thrown against the rocker arm or lifter, every time it shuts, it is
slammed back to the head. (Maybe it bounces, and makes TWO round trips
every valve cycle.)

Jon

On Mon, 7 Mar 2005 09:30:39 +1100, "Tom Miller"
wrote:

Gravity
The liquid sodium is heavier than the vapour.

Yeahbut... which way is up?

I thought the heat transfer was effected by the sodium being shaken
from one end of the cavity to the other by the G forces inherent in a
rapidly operating valve. Just my impression tho, I haven't seen the
theory of the things written down anwhere.

Jon Elson wrote:

Tom wrote:

Tom Miller wrote:

The valve stems are not completely filled with sodium. As the valve
heats
up, sodium vapourizes and rises up the valve stem by convection. This



This, in a reciprocating valve? What would keep the sodium at the head
end of the valve?

Yes, exactly. The valves are hammered with hundreds of G's every time
they slam open and shut. Convection would be totally insignificant
under such extreme acceleration. Every time the valve opens, the sodium
is thrown against the rocker arm or lifter, every time it shuts, it is
slammed back to the head. (Maybe it bounces, and makes TWO round trips
every valve cycle.)

Jon

I recall first hearing about sodium filled valve stems in relation to IC
aircraft engines and some racing cars. I just did a little Googling.

Further supporting the theory that "You've got to take the bad with the
good", I found this text related to aircraft engines which claims that
sodium cooling the valve heads can accelerate valve guide wear.

It's from this web page:

http://www.prime-mover.org/Engines/Marvel/tbo3.html

**********************************

The Problem of Sodium Filled Valves

As revealed above, sodium filled valves in the O-320 engine did not
eliminate valve distress problems. To the contrary, our question is
whether or not they either cause or increase these problems. Sodium
filled valves are an extremely expensive component that we believe are
greatly to blame for valve/guide distress incidents. They do not make
heat magically disappear, as some would have you believe. All these
valves do, at great monetary expense, is transfer heat from the valve
head to the valve stem, or more generally, from the combustion chamber
to the cylinder head via the valve guide. They merely move heat from
point "a" to point "b." It still has to be eliminated from the cylinder
head by either air cooling or oil cooling or both. The problem is that
valve guides are wearing out prematurely and are doing so in spite of
operators keeping CHT levels in the proper range. Excess heat is the
primary cause of premature guide wear (in a properly assembled
cylinder), as most engine shops will tell you. The problem with sodium
filled valves is that they serve to import even more heat into the guide
by transferring it up from the valve head. Lycoming's long history of
valve/guide failure incidents in the parallel valve cylinders has shown
that there is simply no way that the guide can shed all of its higher
heat load via the cooling fins alone, and Lycoming's design provides for
very little oil to aid in that process. The irony here is that
Continental uses solid stem valves that dissipate most of their heat
into the valve seat. Relatively little comes up the stem and into the
valve guide and yet Continental has an abundance of oil in this area to
aid in heat transfer. If sodium filled valves are needed at all, one
wonders why Continental doesn't use them, since their barrel style
hydraulic lifters provide substantial oil for additional cooling of the
guide and valve. Lycoming's mushroom style lifters do not. We think that
without any change in oil flow to the rocker boxes, Lycoming valve and
guide longevity might well benefit from simply going to solid stem
valves. Unfortunately, these are not available.

************************************************** ****

Jeff

--
Jeffry Wisnia

(W1BSV + Brass Rat '57 EE)

"As long as there are final exams, there will be prayer in public
schools"

On Sun, 06 Mar 2005 18:28:02 -0500, Jeff Wisnia
wrote:

**********************************

The Problem of Sodium Filled Valves

As revealed above, sodium filled valves in the O-320 engine did not
eliminate valve distress problems. To the contrary, our question is

Snip..

Whoever wrote that never owned a turbo charged Volvo.



Regards,

Boris Mohar

Got Knock? - see:
Viatrack Printed Circuit Designs (among other things) http://www.viatrack.ca

Below was cribbed from a website:



From MB tech literatu
"Sodium is a heat-conducting element. Sodium fuses and becomes liquid at
an approximate 97 degree in running engine and conducts the heat on
valve head to valve stem by convection. Heat on the valve stem first
conducted to valve guide second to cylinder head then finally
transferred to the cooling water. Cooled sodium sinks to the bottom and
fuses again. Cooling of the valves continuously repeated by this method.
When a sodium filled valve is compared with the same dimensional valve
without sodium, a heat difference of 80 to 150 degree is reported at
valve head circle as well as at the critical point where the valve stem
and head radius intersects. This is one of the major facts on resistance
of the material. Furthermore valve weight is reduced by 7% - 16% by the
drilled volume. This enables a considerable reduction of mass effect on
high performance valves."

--
Steve Walker
(remove wallet to reply)

David R Brooks wrote:
Sodium boils at 883C = 1620F (Kaye & Laby). Do they really run that
hot?

1625F is commonly cited as peak exhaust gas temperature for IC aircraft
engines. The measurement is usually taken several inches from the
exhaust port, so valve temperature could run a little higher.

"Tom Miller" wrote:

:The valve stems are not completely filled with sodium. As the valve heats
:up, sodium vapourizes and rises up the valve stem by convection. This
:carries the heat up to the top of the stem where it is dissipated by the oil
:and air surrounding it. The sodium condenses and falls back to the bottom of
:the valve and collects heat from the seat and continues the cycle. It
:effectively forms a "heat pipe" to transfer the heat away from the seat .
:
:Tom

Most aircraft engines today have horizontal cylinders, thus horizontal
valves.

:"Artemia Salina" wrote in message
m...
: Dumb question I guess, but why do engine manufacturers make
: valve stems that are filled with sodium (I think only exhaust
: valves are sodium filled). Is it a heat expansion issue?
:
: Thanks.
:
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: 0:-) 0:-) 0:-) 0:-) (-:0 (-:0 (-:0 (-:0
: 0:-) Artemia Salina (-:0
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: 0:-) 0:-) 0:-) 0:-) (-:0 (-:0 (-:0 (-:0
:
:

Artemia Salina wrote:
On Sun, 06 Mar 2005 16:39:01 -0500, Jeff Wisnia wrote:



AFAIK sodium filled valve stems operated on the thermosyphon principle.
The sodium "absorbed" heat by evaporating at the part of the stem near
the valve head and delivered it to the other end where the sodium
condensed and the heat it gave off was transferred out through the valve
guides.

Somewhat similar to "heat pipes" but without the wick inside:

http://www.thermacore.com/hpt.htm


Thanks for all the responses. As food for thought, what got me
looking at IC engine valves was the idea to remove the cam, rocker
arms, lifters, and etc. and replace it all with computer controlled
solenoid actuators. Needless to say, someone is already working on
this, with several enticing prototypes under his/her belt:

http://rbowes1.11net.com/dbowes/index.htm

That's almost exactly the idea that I'd had! Neat!


There is an article in the current HSM with instructions to build a
4-stroke engine using solenoid-operated valves.

--
- -
Rex Burkheimer
WM Automotive
Fort Worth TX

On Sun, 06 Mar 2005 17:01:45 -0500, Artemia Salina wrote:
On Sun, 06 Mar 2005 16:39:01 -0500, Jeff Wisnia wrote:


AFAIK sodium filled valve stems operated on the thermosyphon principle.
The sodium "absorbed" heat by evaporating at the part of the stem near
the valve head and delivered it to the other end where the sodium
condensed and the heat it gave off was transferred out through the valve
guides.

Somewhat similar to "heat pipes" but without the wick inside:

http://www.thermacore.com/hpt.htm

Thanks for all the responses. As food for thought, what got me
looking at IC engine valves was the idea to remove the cam, rocker
arms, lifters, and etc. and replace it all with computer controlled
solenoid actuators.

If you're looking for a solidly made, easy to work on engine with
sodium valves, any Saab 2 Liter engine since about 1978 (maybe earlier)
will have the sodium filled exhaust valves. I'd pick a mid-1980's
or later turbo engine, personally, but you can choose between an 8
valve and a 16 valve head for the later ones. Well built engines,
excellent for experimentation. If you get one with the Bosch CIS
fuel injection (up to about '86), fuel management is simply handled.

On Sun, 06 Mar 2005 18:28:02 -0500, Jeff Wisnia wrote:

I recall first hearing about sodium filled valve stems in relation to IC
aircraft engines and some racing cars. I just did a little Googling.

Further supporting the theory that "You've got to take the bad with the
good", I found this text related to aircraft engines which claims that
sodium cooling the valve heads can accelerate valve guide wear.

Saab engines typically do many hundreds of thousands of miles, and I've
never done or even heard of anyone having to redo the valve guides.

Artemia Salina wrote:

Dumb question I guess, but why do engine manufacturers make
valve stems that are filled with sodium (I think only exhaust
valves are sodium filled). Is it a heat expansion issue?

Thanks.

--
0:-) 0:-) 0:-) 0:-) (-:0 (-:0 (-:0 (-:0
0:-) Artemia Salina (-:0
0:-) Surrounded by Angels (-:0
0:-) 0:-) 0:-) 0:-) (-:0 (-:0 (-:0 (-:0

It is a misnomer, the stems were generally only filled to 60%
of the cavity space which included that in the valve head.
At operating temps, the sodium was molten and transfered heat
from the valve head to the cylinder head via the stem & valve
guide.

Tom

Tom Miller wrote:

The valve stems are not completely filled with sodium. As the valve heats
up, sodium vapourizes and rises up the valve stem by convection. This
carries the heat up to the top of the stem where it is dissipated by the oil
and air surrounding it. The sodium condenses and falls back to the bottom of
the valve and collects heat from the seat and continues the cycle. It
effectively forms a "heat pipe" to transfer the heat away from the seat .

Tom

"Artemia Salina" wrote in message
...
Dumb question I guess, but why do engine manufacturers make
valve stems that are filled with sodium (I think only exhaust
valves are sodium filled). Is it a heat expansion issue?

Thanks.

--
0:-) 0:-) 0:-) 0:-) (-:0 (-:0 (-:0 (-:0
0:-) Artemia Salina (-:0
0:-) Surrounded by Angels (-:0
0:-) 0:-) 0:-) 0:-) (-:0 (-:0 (-:0 (-:0


This, in a reciprocating valve? What would keep the sodium
at the head end of the valve?

Tom

Tom Miller wrote:

Gravity
The liquid sodium is heavier than the vapour.

Tom
"Tom" wrote in message
...
Tom Miller wrote:

The valve stems are not completely filled with sodium. As the valve
heats
up, sodium vapourizes and rises up the valve stem by convection. This
carries the heat up to the top of the stem where it is dissipated by the
oil
and air surrounding it. The sodium condenses and falls back to the
bottom of
the valve and collects heat from the seat and continues the cycle. It
effectively forms a "heat pipe" to transfer the heat away from the seat
.

Tom

"Artemia Salina" wrote in message
...
Dumb question I guess, but why do engine manufacturers make
valve stems that are filled with sodium (I think only exhaust
valves are sodium filled). Is it a heat expansion issue?

Thanks.

--
0:-) 0:-) 0:-) 0:-) (-:0 (-:0 (-:0 (-:0
0:-) Artemia Salina (-:0
0:-) Surrounded by Angels (-:0
0:-) 0:-) 0:-) 0:-) (-:0 (-:0 (-:0 (-:0


This, in a reciprocating valve? What would keep the sodium
at the head end of the valve?

Tom

Yeah right. You've never shaken a halfilled bottle of water up & down?

Jeff Wisnia wrote:

Jon Elson wrote:

Tom wrote:

Tom Miller wrote:

The valve stems are not completely filled with sodium. As the valve
heats
up, sodium vapourizes and rises up the valve stem by convection. This



This, in a reciprocating valve? What would keep the sodium at the head
end of the valve?

Yes, exactly. The valves are hammered with hundreds of G's every time
they slam open and shut. Convection would be totally insignificant
under such extreme acceleration. Every time the valve opens, the sodium
is thrown against the rocker arm or lifter, every time it shuts, it is
slammed back to the head. (Maybe it bounces, and makes TWO round trips
every valve cycle.)

Jon

I recall first hearing about sodium filled valve stems in relation to IC
aircraft engines and some racing cars. I just did a little Googling.

Further supporting the theory that "You've got to take the bad with the
good", I found this text related to aircraft engines which claims that
sodium cooling the valve heads can accelerate valve guide wear.

It's from this web page:

http://www.prime-mover.org/Engines/Marvel/tbo3.html

**********************************

The Problem of Sodium Filled Valves

As revealed above, sodium filled valves in the O-320 engine did not
eliminate valve distress problems. To the contrary, our question is
whether or not they either cause or increase these problems. Sodium
filled valves are an extremely expensive component that we believe are
greatly to blame for valve/guide distress incidents. They do not make
heat magically disappear, as some would have you believe. All these
valves do, at great monetary expense, is transfer heat from the valve
head to the valve stem, or more generally, from the combustion chamber
to the cylinder head via the valve guide. They merely move heat from
point "a" to point "b." It still has to be eliminated from the cylinder
head by either air cooling or oil cooling or both. The problem is that
valve guides are wearing out prematurely and are doing so in spite of
operators keeping CHT levels in the proper range. Excess heat is the
primary cause of premature guide wear (in a properly assembled
cylinder), as most engine shops will tell you. The problem with sodium
filled valves is that they serve to import even more heat into the guide
by transferring it up from the valve head. Lycoming's long history of
valve/guide failure incidents in the parallel valve cylinders has shown
that there is simply no way that the guide can shed all of its higher
heat load via the cooling fins alone, and Lycoming's design provides for
very little oil to aid in that process. The irony here is that
Continental uses solid stem valves that dissipate most of their heat
into the valve seat. Relatively little comes up the stem and into the
valve guide and yet Continental has an abundance of oil in this area to
aid in heat transfer. If sodium filled valves are needed at all, one
wonders why Continental doesn't use them, since their barrel style
hydraulic lifters provide substantial oil for additional cooling of the
guide and valve. Lycoming's mushroom style lifters do not. We think that
without any change in oil flow to the rocker boxes, Lycoming valve and
guide longevity might well benefit from simply going to solid stem
valves. Unfortunately, these are not available.

************************************************** ****

Jeff

--
Jeffry Wisnia

An opinion specific to a particular engine design, hardly an opinion
shared by Pratt & Whitney, Wright, Allison, Ranger, RR, de Havilland,
Daimler-Benz, Alfa Romeo, Junkers, Hispano Suiza and also Continental
to name just a few makers who used sodium cooled exhaust valves in their
aircraft engines.

Tom

Tom

http://www.prime-mover.org/Engines/Marvel/tbo3.html

The Problem of Sodium Filled Valves

It appears this pertains to air cooled aircraft engines.
Water cooling is much better at eliminating hot spots.

That said, there are lots of auto engines with sodium
valves and I'm sure that major car manufactures would not
do it if there wasn't benefit.

chuck

one
wonders why Continental doesn't use them, since their barrel style
hydraulic lifters provide substantial oil for additional cooling of
the
guide and valve. Lycoming's mushroom style lifters do not.

Lycoming uses hydraulic lifters in all but the O-235 series engines,
and whether hydraulic or not, they send oil up the pushrod to the
rocker and valve stems. They are located above the rocker shafts and
valves, and get plenty of oil on them. Lycoming's camshaft is above the
crank and tends to get little cam lube at idle. Continentals have their
cams at the bottom, getting lots of oil, but the valves are high and
get a bit less drip. They have a gallery thru the rocker to make sure
some oil gets to the rocker tip and valve stem.
Lycomings problems are not so different from Continentals. I've had
much more valve trouble in the small Continentals than in the Lycs, and
what valve trouble Lycs give is due more to the guide material (appears
to be bronze), which doesn't have really good wearability at high
temps. First sign of trouble is a leaky exhaust valve, as the guide is
allowing it to seat a bit off-center and wearing one edge.

Dan

I had a 1976 with a simple fuel injection system, I also worked at a dealer
in 1986 ish the 1974-1989 (I think 1989) had more power than the next
generation. same specs but the older "b" motors just ran like raped apes, I
think they under rated there HP.
"Dave Hinz" wrote in message
...
On Sun, 06 Mar 2005 17:01:45 -0500, Artemia Salina
wrote:
On Sun, 06 Mar 2005 16:39:01 -0500, Jeff Wisnia wrote:


AFAIK sodium filled valve stems operated on the thermosyphon principle.
The sodium "absorbed" heat by evaporating at the part of the stem near
the valve head and delivered it to the other end where the sodium
condensed and the heat it gave off was transferred out through the valve
guides.

Somewhat similar to "heat pipes" but without the wick inside:

http://www.thermacore.com/hpt.htm

Thanks for all the responses. As food for thought, what got me
looking at IC engine valves was the idea to remove the cam, rocker
arms, lifters, and etc. and replace it all with computer controlled
solenoid actuators.

If you're looking for a solidly made, easy to work on engine with
sodium valves, any Saab 2 Liter engine since about 1978 (maybe earlier)
will have the sodium filled exhaust valves. I'd pick a mid-1980's
or later turbo engine, personally, but you can choose between an 8
valve and a 16 valve head for the later ones. Well built engines,
excellent for experimentation. If you get one with the Bosch CIS
fuel injection (up to about '86), fuel management is simply handled.

On Thu, 10 Mar 2005 23:05:04 -0500, Waynemak wrote:
I had a 1976 with a simple fuel injection system, I also worked at a dealer
in 1986 ish the 1974-1989 (I think 1989) had more power than the next
generation. same specs but the older "b" motors just ran like raped apes, I
think they under rated there HP.

Yes, the 8-valve B engine with turbo, really really goes. Mine is in a '78
99 Turbo, so it's lighter than the 900, which probably helps. Hella fun car.