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Which heads on a 4.8l Turbo motor? 243 or 317 heads?

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Old 12-09-2011, 11:23 AM
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243s unless plan on 30psig, then go with the 317s.
Don't mill if don't have to.
If have to, keep under .010.
.005 if possible
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Old 12-09-2011, 11:42 AM
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Run a set of ported 862s. a 4.8 is going to be a dog out of boost with low compression. You can safely run 15 psi on 9.8:1 compression, its all in the tune. Do not mill a head for boost applications.
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Old 12-09-2011, 11:53 AM
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Originally Posted by pewterliftedz
Run a set of ported 862s. a 4.8 is going to be a dog out of boost with low compression. You can safely run 15 psi on 9.8:1 compression, its all in the tune. Do not mill a head for boost applications.
X2 !!!

Personally I wouldn't try to push it past 15 although guys have reported runing as much as 19 PSI with a conservative Tune...
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Old 12-09-2011, 12:36 PM
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So why not mill the heads? It it because of higher compression or because the heads have a weak point?
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Old 12-09-2011, 03:51 PM
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Originally Posted by 03regcab sierra
So why not mill the heads? It it because of higher compression or because the heads have a weak point?
Because you weaken the deck and lose clamping force. This would make it more likely to lift a head gasket under boost conditions.
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Old 12-10-2011, 10:34 AM
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Originally Posted by 1FastBrick
Personally I wouldn't try to push it past 15 although guys have reported runing as much as 19 PSI with a conservative Tune...
24 on an LQ9 in my friends car. And another friend of mine ran 19 in an L33.
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Old 12-28-2011, 09:35 PM
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ill go for 317 heads for low compression for boost
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