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Here's a fun swap donor


Guest jdllaugh

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It would be a nice swap, but after seeing how many problems these new engines are having, I'll never own one. Did you know that the valves are actually hollow and they are filled with sodium? Just do a search on Yahoo or Google or whatever, you'll be suprised at what you find out.

 

!M!

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Guest Anonymous

The sodium valves create a splash effect that removes heat from the combustion chamber, resulting in higher rpm limits and far more efficient cooling, to the added effect of densifying? the air/fuel mixture.

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Sodium filled valves were common fare back in the 70's to help cars cope with unleaded gas.

 

Maybe it cools the intake air. But I think it is more to keep the valve from burning up since they no longer have the lead to help lubricate them.

 

BTW, few things conduct heat more readily then sodium. That is why some nuclear reactors were cooled with pure liquid sodium.

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I'm calling your bluff here. Some of these assumptions are way off.

But first, I would love to have that motor in my car. Period. I have the previous version in my M coupe and it is incredible.

But I digress.

Sodium filled valves are really for one purpose. To help the exhaust valve withstand more heat. It helps keep the valve cooler by transfering heat away from the end of the valve and into the head. Under high heat, the sodium

becomes a liquid and splashes up and down inside the hollow valve stem. If this is what you were refering to by splash effect, ok, but I have never heard it called that before. So in that respect, it does have better cooling, but it is a far cry from "far more efficient". The only time the valve head could transfer heat was when it was on the seat. Now, think about that liquid sodium when you extend the valve, it rushes up to the top of the valve stem, with all its heat, and lets it transfer its heat out then. Next, as the valve closes, it rushes back down to the valve head where it can transfer heat out to the valve seat. It is not just transfering it out, but absorbing the heat as well.

Next, it has nothing at all to do with high rpm limits. If anything, in really,(over 10k) high rpm motors they won't use sodium filled valves, since you are introducing a liquid that is moving up and down, often in the opposite direction of the valve. It may not be much weight, but take that at 9-10,000 rpm and it starts to become significant. They are used in race motors and exotics,(ferrari, etc..), but there is a limit to what they can take, and they are not really used to gain a higher rpm limit. The exhaust valve is usually the hottest part in the combustion chamber, hence the need to cool it a little better than the other stuff. Sodium filled valves are lighter than a conventional valve, and that is why you often see them in high powered, higher rpm motors. It is really a mid to high rpm design. It is not really a high rpm motorcycle type design.

Think about this, VW motors use those valves, Air cooled, gets kinda hot.... I once saw a reference to VW motors that went like this:

 

What a VW motors sounds like at idle: putt, putt, putt.

 

What it sounds like at Redline: putt, putt, putt.

 

Sorry, good side humor.

 

And the reference to making the air more dense, remember, we are talking about the exhaust flow, not intake. The idea is to keep heat from the valve seat and transfer it up to the cylinder head. I seriously doubt it is a noticable or measurable difference in the temp of the outgoing air charge with a sodium filled valve vs. the other.

Not picking on you in particular, but just wanted to clear some of this up. They actually started this with NaCl, or table salt in the valves, and eventually got to the metal sodium.

-Bob

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Guest Anonymous

I would think Titanium valves would be the valve of choice, especially when you see NASCAR engines turning 9000 R's for 500 miles without failure, stronger and lighter.

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Guest silverbullet

Just my $.02 but from what I can remember what I was told/read the sodium filled valves are mainly to withstand more heat from more efficient heat transfer, I don't really think it helps the air density/charge/efficiency.

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Guest Anonymous

Nissan uses those type of valves too, in the SR20s in the silvias. This is according to my service manual for the 94 and up models, probably the same on the earlier SRs too.

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  • 4 weeks later...
Originally posted by Mat73GNZ:

[QB]Did you know that the valves are actually hollow and they are filled with sodium?[QB]

Alot of cars are like that and it shouldn't cause any problems, usually the exaust valves, the LT4 for instance. If they are having problems with the valves its a design issue on wall thickness or MFG tollerances (which would be a supprise).
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That would be fun motor. I just had the same thought today. Nothing like an inline motor that makes a ton of power and is generally accepted as being a reliable motor. What about an M3?? Here is a link to a place that sells rebuilt motors. They aren't cheap but they have 2 yr unlimited mi warranties. I would love to have a 98 M3 motor. They aren't as powerful as the latest motor but a beatiful motor non the less.

 

http://www.bmrparts.com/engine1a.htm

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