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Which head will yield more power....

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Old Dec 26, 2008 | 11:10 AM
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Default Which head will yield more power....

A set of 317's or 243's? Pretty much on a mild cammed, full bolt on ls1? pros/cons of both please.
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Old Dec 26, 2008 | 02:36 PM
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They flow the same and have the same port size 210/75cc. The only diff is the combustion chamber volume. 64.45 for the 243 and 71.06 for the 317. The 317s are good for forced induction due to the lower compression.

If you plan on staying all motor go with the 243 ls6 head.
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Old Dec 26, 2008 | 05:18 PM
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Originally Posted by Silver_TransAm
They flow the same and have the same port size 210/75cc. The only diff is the combustion chamber volume. 64.45 for the 243 and 71.06 for the 317. The 317s are good for forced induction due to the lower compression.

If you plan on staying all motor go with the 243 ls6 head.
I'm no expert, and haven't seen any back to back tests, but this is what I was always told too. They are basically the same except the 243's have a smaller cc volume. I've seen a lot of forced induction guys go with the 317's for the reason listed above as well.
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Old Dec 26, 2008 | 09:59 PM
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So on a NA engine would the 317's with lower compression hurt performance? If so how much ?
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Old Dec 26, 2008 | 10:11 PM
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just get the 243s for all motor and the 317s for boost
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Old Dec 26, 2008 | 10:20 PM
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Compression is power, if you are going to buy new pistons then you can tailor the compression to be what you want it to be.
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Old Dec 29, 2008 | 10:01 PM
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^ compression= power, all mods are to boost oxygen and compression, thats why S/C and T/C are such big power-adders
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Old Dec 29, 2008 | 10:28 PM
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All things being equal, the 243 heads will make more power under the curve due to the higher compression. If you are staying N/A go with the 243 heads, maybe even add a thinner head gasket to raise compression. If you have any plans for forced induction go with the 317 heads, it will help when you do add boost.
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