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Old 11-30-2012, 04:57 PM   #26
nottofast
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design flaw
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Old 11-30-2012, 05:06 PM   #27
FuJi K
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Quote:
Originally Posted by NW2TONE
you would like to buy some crack?????
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Old 11-30-2012, 06:44 PM   #28
NW2TONE
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Quote:
Originally Posted by tja1618 View Post
Just found that my 2003 WRX heads have the infamous cracks. Was planning to use these in a hybrid build, but now I'm just going to get new castings to go along with the new EJ257.



How can I prevent this with a new engine? I'm going to have the new heads chamber matched and ported.
those cracks aint ****. run it. you wont notice a differance.
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Old 11-30-2012, 07:25 PM   #29
djdalaney
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I'd say worst case scenario, you end up with some knock once in a while if the crack is sharp enough to create rough edges that heat up more than the rest of the combustion chamber and ignite the fuel. As long as they pass a pressure test and aren't massive cracks, it shouldn't cause any major issues. Of course, you always run the risk of them getting worse over time and THEN causing problems.
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Old 12-01-2012, 09:42 AM   #30
tja1618
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I wouldnt be so worried if it weren't for all the machining I have planned. I'll probably just buy new head castings since they're only about $1,200 for a set. I just don't feel comfortable putting cracked heads on an otherwise brand new motor.

This new motor is going to be meticulously maintained, so I just want to do what I can to prevent the new heads from cracking.
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Old 12-27-2012, 11:33 PM   #31
spoolinred
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Well lets say you were shooting for high hp (600-650whp)on a cnc'd hybrid build with heads that had small cracks do you think it would be a bigger issue opposed to someone that is only running a smaller turbo and lower hp?
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Old 05-25-2013, 07:33 PM   #32
HiImZackJones
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Quote:
Originally Posted by RaceFaceXC View Post
In Aircraft Engines cracking between plug hole and Exhaust valve seat is not uncommon and it's attributed to heat Management. This is supported by improved cooling fin design in the area reducing or stopping the problem from happening and that it's often found on Engines with poor baffle seal.

Does anyone have cylinder head temp probes on an Engine where the cracking occurred? Is there a trend in what cylinder the heads are cracking on?
I hate to reply to this so many months after but I have seen damage happen on cylinder #4 first in most cases. The unequal header length tends to create more tear on that cylinder due to it being the longest length.
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