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Old 03-27-2020, 04:08 PM   #1
enduroxt
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Member#: 310796
Join Date: Feb 2012
Location: UT
Vehicle:
05 obxt

Default ED3 vs ED4 exhaust valves -- what are the diff?

I have an interesting situation where I have ED3 valves installed on one head and ED4 on the other (B25 heads).
The FSM states that oem valves are sodium filled. Simple question: what are the difference between ED3 and ED4 valves?
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Old 04-08-2020, 01:55 PM   #2
Homemade WRX
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I'm actually curious but I don't know. I don't often play with OEM valvetrain.
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Old 02-17-2021, 08:33 PM   #3
Scargod
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silver gray metallic

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Quote:
Originally Posted by enduroxt View Post
I have an interesting situation where I have ED3 valves installed on one head and ED4 on the other (B25 heads).
The FSM states that oem valves are sodium filled. Simple question: what are the difference between ED3 and ED4 valves?
Oh, yeah, your ID says '05 OBXT. I was wondering what car/engine.
I can't see how this is helpful. Heads aren't alike? Are the ED3 or ED4 sodium-filled?
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Old 02-17-2021, 10:57 PM   #4
enduroxt
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I am pretty sure the ED3 valves are sodium filled as they cost like 60$ a piece, while the ED4 valves are most likely not (20$ a piece) and a little difference in weight.
IIRC, Subaru switched to ED4 at one point for most turbo EJ engines.
As for me, I just kept the ED3s on one head and the ED4s on the other. My engine was like that most likely as a result of a partial head rebuild before I purchased the car.
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