[Z06] Sodium Filled Exhaust Valves
08-23-2013, 05:03 PM
#1
Safety Car
Thread Starter
Sodium Filled Exhaust Valves
Plausible explanation of valve failures
"Urritia: Sodium-based valves were manufactured in the ’60s when then aerospace industry had piston-driven engines and needed to find a way to cool down the exhaust valves. They were eventually manufactured for the OE automotive industry and are still used today. They work well in controlled environments where the temperature change is not drastic. If you installed sodium-filled valves in an racing engine, you will find issues with the sodium not working properly to cool the bottom area of the stem of the valve. The sodium would stop working and create a possible failure where the valve is now hollow in that area."
Yes, I know, they didn't all fail in a racing environment but it does help explain what happens, if even just a little bit.
from http://www.enginelabs.com/features/e...alyzes-valves/
"Urritia: Sodium-based valves were manufactured in the ’60s when then aerospace industry had piston-driven engines and needed to find a way to cool down the exhaust valves. They were eventually manufactured for the OE automotive industry and are still used today. They work well in controlled environments where the temperature change is not drastic. If you installed sodium-filled valves in an racing engine, you will find issues with the sodium not working properly to cool the bottom area of the stem of the valve. The sodium would stop working and create a possible failure where the valve is now hollow in that area."
Yes, I know, they didn't all fail in a racing environment but it does help explain what happens, if even just a little bit.
from http://www.enginelabs.com/features/e...alyzes-valves/
08-23-2013, 05:24 PM
#2
08-23-2013, 06:31 PM
#6
I already know... I was checking to see if the OP understood what he posted 
(and I'm not all that sure Zeke understood what he said 
)
.
(and I'm not all that sure Zeke understood what he said ).
Last edited by Mark2009; 08-23-2013 at 06:34 PM.
08-23-2013, 07:12 PM
#7
Safety Car
Thread Starter
But instead of questioning me, perhaps you could educate us on why you believe the article is wrong. I'm not here for a pissing contest, I posted an article that though may be helpful in shedding some light on some of the failures to the valves.
We have speculated poor machining, supported by GM, poor quality of the valves to excessive heat at the guides, well, this article provides some basis to the heat transfer theory. It could be a combination of all three.
08-23-2013, 07:27 PM
#8
Melting Slicks
It's my understanding that the sodium in the valves is in a liquid form and cools the valve by transferring the heat faster to the guides than a solid stem valve. Unfortunately, once the sodium reaches it's boiling point it turns to a gaseous state which severely impacts the cooling effect and leads to failures... as stated in the article.
But instead of questioning me, perhaps you could educate us on why you believe the article is wrong. I'm not here for a pissing contest, I posted an article that though may be helpful in shedding some light on some of the failures to the valves.
We have speculated poor machining, supported by GM, poor quality of the valves to excessive heat at the guides, well, this article provides some basis to the heat transfer theory. It could be a combination of all three.
But instead of questioning me, perhaps you could educate us on why you believe the article is wrong. I'm not here for a pissing contest, I posted an article that though may be helpful in shedding some light on some of the failures to the valves.
We have speculated poor machining, supported by GM, poor quality of the valves to excessive heat at the guides, well, this article provides some basis to the heat transfer theory. It could be a combination of all three.
Others believe that the valve is causing the guide to wear from heat possibly from the cause stated in this article. GM says otherwise and that its a geometry problem in the guide. I have also heard other excuses like inconsistent wall thickness.
08-23-2013, 08:13 PM
#9
It's my understanding that the sodium in the valves is in a liquid form and cools the valve by transferring the heat faster to the guides than a solid stem valve. Unfortunately, once the sodium reaches it's boiling point it turns to a gaseous state which severely impacts the cooling effect and leads to failures... as stated in the article.
But instead of questioning me, perhaps you could educate us on why you believe the article is wrong. I'm not here for a pissing contest, I posted an article that though may be helpful in shedding some light on some of the failures to the valves.
We have speculated poor machining, supported by GM, poor quality of the valves to excessive heat at the guides, well, this article provides some basis to the heat transfer theory. It could be a combination of all three.
But instead of questioning me, perhaps you could educate us on why you believe the article is wrong. I'm not here for a pissing contest, I posted an article that though may be helpful in shedding some light on some of the failures to the valves.
We have speculated poor machining, supported by GM, poor quality of the valves to excessive heat at the guides, well, this article provides some basis to the heat transfer theory. It could be a combination of all three.
The commonly reported facts of the matter are that the sodium does not reach a gaseous state until around 1600*F, which is far beyond the design limit of the LS7. Now while certain full race engines might reach that temp on the exhaust valve, as Mr. Urrutia seems to have been implying, that has absolutely nothing to do with the LS7 since it is not intended to reach that temperature.
If it is reaching that temperature, then the solution is to find out why and prevent it from doing so, not to replace the valve with a different type (which under the same conditions would likely reach that temperature as well... contrary to what may pass as conventional wisdom around here, there has been no presentation of any engineering data or theory stating that a non-sodium hollow valve runs any hotter than a solid valve, nor that a gaseous sodium valve is going to run any hotter than a plain hollow valve).
What you perceive as a pissing contest is instead an attempt to illustrate that poorly understood concepts should not be posted as fact or as workable explanations for things to which they do not apply. With all due respect the net result of your OP is not to inform, but to cast yet another poorly aimed arrow at an item that has been judged guilty without any type of a fair trial or rational examination. The simple answer for quite some time is that valves are failing because the guides are worn out... and the sum total of CF resistance to that simple explanation is quite stupefying. Whether the worn guides are inducing excessive stress or excessive heat or a combination thereof is irrelevant to solving the problem unless the goal is to employ a valve that will survive operation in a worn out guide (rotsa ruck wit dat).
Last edited by Mark2009; 08-23-2013 at 08:32 PM.
08-23-2013, 08:29 PM
#10
.
Last edited by Mark2009; 08-23-2013 at 08:31 PM.
08-23-2013, 08:36 PM
#11
Race Director
I was reading a bit on the hemi motors in the charger and challenger..guess what type of valves they use ... I don't think valves are the issue ...its the guides in the LS7 .
08-23-2013, 09:08 PM
#13
Burning Brakes
Member Since: Jul 2002
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I treat the word sodium as a very basic generic term for marketing material as it's used in valve applications like this. It would be nice for someone in-the-know to explain what IS sodium in a chem sense is in this application. Perhaps there is an SAE paper on sodium valves someone has access to?
Simple fact is sodium valves have been used for a long time, are still used and will continue to be used by many manufacturers. WITHOUT FAILURE.
I understand condemning something most doesn't understand is rapidly becoming this nations past time, but the easy way out doesn't make it the truth.
In relation to the LS7... well, given that the head guides wear no matter what the guide material or the material of the valve regardless, condemning the 'sodium valve' as the culprit is taking the simplest way out.
And yes, I understand that a hollow does not have the same strength properties as a solid, but in the same respect, take a sodium valve out and put in a plain hollow SS and I don't think you are improving you odds or buying any more time. Heck, we already have read posts here that even with solids excessive guide wear is still present.
Sounds like if you want to escape the LS7 head issues, you might want to try a different LS (or LT???) head version all together
08-23-2013, 10:01 PM
#14
Safety Car
Thread Starter
By questioning you I determine your level of understanding. You couldn't have understood the article you linked, mainly because it was lacking in specific information. In fact, there was no mention in the article of sodium being in a gaseous state, so you are mixing and matching what you've read in various places and coming to a conclusion not supported by any facts (the sodium 'stops working' and that lets/makes the valve break... implication, get rid of the sodium and the valve won't break.... conclusion, the sodium is making the valves break).
The commonly reported facts of the matter are that the sodium does not reach a gaseous state until around 1600*F, which is far beyond the design limit of the LS7. Now while certain full race engines might reach that temp on the exhaust valve, as Mr. Urrutia seems to have been implying, that has absolutely nothing to do with the LS7 since it is not intended to reach that temperature.
If it is reaching that temperature, then the solution is to find out why and prevent it from doing so, not to replace the valve with a different type (which under the same conditions would likely reach that temperature as well... contrary to what may pass as conventional wisdom around here, there has been no presentation of any engineering data or theory stating that a non-sodium hollow valve runs any hotter than a solid valve, nor that a gaseous sodium valve is going to run any hotter than a plain hollow valve).
What you perceive as a pissing contest is instead an attempt to illustrate that poorly understood concepts should not be posted as fact or as workable explanations for things to which they do not apply. With all due respect the net result of your OP is not to inform, but to cast yet another poorly aimed arrow at an item that has been judged guilty without any type of a fair trial or rational examination. The simple answer for quite some time is that valves are failing because the guides are worn out... and the sum total of CF resistance to that simple explanation is quite stupefying. Whether the worn guides are inducing excessive stress or excessive heat or a combination thereof is irrelevant to solving the problem unless the goal is to employ a valve that will survive operation in a worn out guide (rotsa ruck wit dat).
The commonly reported facts of the matter are that the sodium does not reach a gaseous state until around 1600*F, which is far beyond the design limit of the LS7. Now while certain full race engines might reach that temp on the exhaust valve, as Mr. Urrutia seems to have been implying, that has absolutely nothing to do with the LS7 since it is not intended to reach that temperature.
If it is reaching that temperature, then the solution is to find out why and prevent it from doing so, not to replace the valve with a different type (which under the same conditions would likely reach that temperature as well... contrary to what may pass as conventional wisdom around here, there has been no presentation of any engineering data or theory stating that a non-sodium hollow valve runs any hotter than a solid valve, nor that a gaseous sodium valve is going to run any hotter than a plain hollow valve).
What you perceive as a pissing contest is instead an attempt to illustrate that poorly understood concepts should not be posted as fact or as workable explanations for things to which they do not apply. With all due respect the net result of your OP is not to inform, but to cast yet another poorly aimed arrow at an item that has been judged guilty without any type of a fair trial or rational examination. The simple answer for quite some time is that valves are failing because the guides are worn out... and the sum total of CF resistance to that simple explanation is quite stupefying. Whether the worn guides are inducing excessive stress or excessive heat or a combination thereof is irrelevant to solving the problem unless the goal is to employ a valve that will survive operation in a worn out guide (rotsa ruck wit dat).
I stated long ago that I believed it to be a geometry problem. This was back when LG said they were looking into the problem. I have also stated in the past the LS6 didn't have the same failures as seen by the LS7, even though they used a sodium filled valve, when people were blaming the valves.
You can't have a valve wallowing around in a guide and still expect it to effectively transfer heat to the guide. So yes, I can see it being a contributing factor to the failure, but not the initial, nor did I say it was the initial cause.
08-23-2013, 11:33 PM
#17
Instructor
Yes i have just replaced my exhaust guides with bronze ones and used factory ex valves couldnt see any reason to replace with SS type but have only done 1500ks since full rebuild of engine so i can only hope there will be no problems, no reason that i can think of ,any after market alloy head you buy always has bronze guides so they must work,good luck
08-23-2013, 11:42 PM
#18
Team Owner
Every time I see someone post that the sodium valves are junk because the sodium turns to gas at 1600*F I just have to wonder if anyone even stopped for a millisecond to think about what 1600*F is and what it takes to reach that temp INTERNALLY in a valve up the stem. Not to mention 1621*F is the boiling temp of element sodium if I'm not mistaken and likely not in a vacuum state or sealed state. Some of your chemistry geniuses fill us in, but if I recall even a smidge from 25yrs ago high school chem, boiling points have many external factors.
I treat the word sodium as a very basic generic term for marketing material as it's used in valve applications like this. It would be nice for someone in-the-know to explain what IS sodium in a chem sense is in this application. Perhaps there is an SAE paper on sodium valves someone has access to?
Simple fact is sodium valves have been used for a long time, are still used and will continue to be used by many manufacturers. WITHOUT FAILURE.
I understand condemning something most doesn't understand is rapidly becoming this nations past time, but the easy way out doesn't make it the truth.
In relation to the LS7... well, given that the head guides wear no matter what the guide material or the material of the valve regardless, condemning the 'sodium valve' as the culprit is taking the simplest way out.
And yes, I understand that a hollow does not have the same strength properties as a solid, but in the same respect, take a sodium valve out and put in a plain hollow SS and I don't think you are improving you odds or buying any more time. Heck, we already have read posts here that even with solids excessive guide wear is still present.
Sounds like if you want to escape the LS7 head issues, you might want to try a different LS (or LT???) head version all together
I treat the word sodium as a very basic generic term for marketing material as it's used in valve applications like this. It would be nice for someone in-the-know to explain what IS sodium in a chem sense is in this application. Perhaps there is an SAE paper on sodium valves someone has access to?
Simple fact is sodium valves have been used for a long time, are still used and will continue to be used by many manufacturers. WITHOUT FAILURE.
I understand condemning something most doesn't understand is rapidly becoming this nations past time, but the easy way out doesn't make it the truth.
In relation to the LS7... well, given that the head guides wear no matter what the guide material or the material of the valve regardless, condemning the 'sodium valve' as the culprit is taking the simplest way out.
And yes, I understand that a hollow does not have the same strength properties as a solid, but in the same respect, take a sodium valve out and put in a plain hollow SS and I don't think you are improving you odds or buying any more time. Heck, we already have read posts here that even with solids excessive guide wear is still present.
Sounds like if you want to escape the LS7 head issues, you might want to try a different LS (or LT???) head version all together
Where are all the heat induced sodium filled two piece valve failures in the LS6 at 10.5:1 compression which has been proven to be a workhorse at the track over many years. 
08-24-2013, 10:07 AM
#19
Race Director
hopefully it does not drop a valve LOL There is one forum member I know of that has done that , but just recently in the last few months, but no reported problems that I know of.
08-24-2013, 11:12 AM
#20
You can contact these members for their input, or you can refer to their prior posts.