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Who installed sodium filled exhaust valves in their new build and why?

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I’m trying to get an idea of why we choose to only substantially update only our exhaust valves.

The intake valves sit there with all this heat in them and our air, after just being sent through a heat exchanger, flow past glowing hot slugs of metal before it gets to the chamber. Returning all this heat back to the air has to be considered if one is doing exhaust valves; if it is being done to help remove excess charge heat.

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Thank for the FYI for the question that was not asked, that all OEM exhaust valves from Subaru are Sodium filled.

They don’t have narrower stems in the area of flow.

They don’t have other enhancements that some would consider worthy of having and therefore buy and replace their OEM valves during their build.

You could answer the question that was asked and contribute to the discussion.

We might even get some insights.

BTW page ME(H4DOTC)-62



Crank Sprocket

17.Crank Sprocket A: REMOVAL


Perform the work with the engine installed to body when replacing a single part.

1) Remove the V-belts. <Ref. to ME(H4DOTC)-41, REMOVAL, V-belt.>

2) Remove the crank pulley.

<Ref. to ME(H4DOTC)-48, REMOVAL, Crank Pul- ley.>

3) Remove the timing belt cover.

<Ref. to ME(H4DOTC)-50, REMOVAL, Timing Belt Cover.>

4) Remove the timing belt.

<Ref. to ME(H4DOTC)-51, REMOVAL, Timing Belt.>

5) Remove the crank sprocket.


1) Check the crank sprocket teeth for abnormal wear and scratches.

2) Make sure there is no free play between crank sprocket and key.

3) Check the crank sprocket protrusion used for sensor for damage and contamination of foreign matter.



1) Install the crank sprocket.


2) Install the timing belt.

<Ref. to ME(H4DOTC)-53, INSTALLATION, Tim- ing Belt.>

3)Install the timing belt cover. <Ref. to ME(H4DOTC)-50, INSTALLATION, Timing Belt Cover.>

4) Install the crank pulley. <Ref. to ME(H4DOTC)- 48, INSTALLATION, Crank Pulley.>

5) Install the V-belts. <Ref. to ME(H4DOTC)-41, INSTALLATION, V-belt.>



This page mentions nothing about valve construction, and this installation manual for this engine is for just one of the many engines under the Subaru banner and so does not represent that all of their exhaust valves are filled with sodium.

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mmh. Strange. Here is a screenshot of the page I was referencing. And I am specifically referring to the 2005-2009 LGT and 2005-2009 OBXT. As far as I understand, the attached screenshot is for these cars. Not sure about the rest of the Subaru fleet.


Edited by xt2005bonbon
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I don't know how many people are changing out valves on the NA vehicles, my understanding is the issue with exhaust valves is mainly an issue on the turbo vehicles due to the open/close delay causing the engine to run lean and burn the exhaust valves.


I just had mine replaced since they were nasty when I got the engine to the machine shop for the short block swap. I was advised that they usually end up needing to rebuild the heads on these cars (turbo ej) and that they usually go for high temp slightly oversize valves. This helps with the burn issue and the construction helps exhaust a little better. I was told the only advantage in getting more robust valves on the intake was to help flow the air in better and wouldn't matter until very high levels of boost.

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When I pulled -62 I got the crank sprocket stuff.

I my case, my first rebuild was replaced with am ej257 block and my head were redone because the valves had been rocking in the guides.

Everything was replaced with cosworth items but it wasn’t until after the build that I stated thinking I should have gotten the intake valves thermal coated.

Are we sure the NA valves are sodium like the ej255 ones?

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Cobb didn’t have their kit that works with a Spec B then.

Chicago area e85 is not consistently 85% and I filled up with something like 35%. It dropped my reading from 77% to 40% with a ten gallon fill up on a sixteen gallon tank. I didn’t do the math on this but you can get the idea.

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Did you not have a map for lower ethanol content?


Its a pain but I have multiple ethanol maps for when the fuel changes for the winter.


Also the pumps near me say that the ethanol content is a minimum of %51 on the "E85" pumps. How do you know it was E35?


As for your original question, I would assume the factory valves are sufficient for %90 of rebuilds and any "upgrade" would not give you benefit enough to justify the cost.

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  • 4 months later...

Late to this thread, but the thinking behind sodium valves being restricted to the exhaust is that the intake valves have fresh, cool air that keeps their temperature down. Exhaust valves only ever deal with hot gases.



[ame=http://www.youtube.com/watch?v=onpyNFKGEYQ]How Sodium Filled Exhaust Valves Work - Kia Stinger GT - Best Engines - YouTube[/ame]

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