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Old 10-27-2015, 06:17 AM   #1
Chali08wrx
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Default Machined heads.

What should I been looking/listening/ect. For?
Will anything change like compression. The motor is a 2008 wrx ej255. When the water pump went the heads warped. No cracks or other problems, but what else should I be concerned about?
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Old 10-27-2015, 06:27 AM   #2
rtv900
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You'd have to say what you had done to the heads.
If they warped and you had those same heads fixed, then yes, compression ratio will absolutely change because nobody straightens heads, they mill the mating face until it's flat. That decreases your combustion chamber size.
Unless you, or the shop, accurately measured the volume before and after it is a total guess at this point.
All you know is it' is higher now.

one other thing to keep in mind, when something warped is milled flat, you take a different amount off the ends than the middle, or one side vs another, depending how it warped.
you'll kind of have to tune to your worst case.
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Old 10-27-2015, 07:34 AM   #3
Chali08wrx
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Just machining flat and cleaning and flushing. So with a tune everything can be accounted for? Running intake, stock turbo, and turbo back. Has a street tune but I figured it would need to be re tuned.
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Old 10-27-2015, 11:28 AM   #4
MrTris
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I wouldn't worry about it. If it was SO much to be taken off, you shouldn't have done it to begin with. Who looked at them and determined that they would be OK with a little machining?

In any case, the minute amount taken off by machining the faces flat, won't affect your CR enough to warrant any major changes, much less worrying about it.
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Old 10-27-2015, 11:51 AM   #5
Chali08wrx
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Water pump failed after it was replaced a compression test was done. The shop determined that the heads had warped. I don't know exact details. It his comes from the dealer making it right. The at ran great before the water pump. Now they are replacing the water pump machining heads and all gaskets. Just trying to see if I will notice any major changes or any major problems that could come after. No cracks in the block others though.
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Old 10-27-2015, 11:55 AM   #6
MrTris
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So, the dealership is doing the work? Perfect! Means that if anything goes sideways, it's on them! Let it ride!
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Old 10-27-2015, 12:24 PM   #7
Chali08wrx
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Sounds good. Thanks just didn't know what to expect.
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