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Advantage to use unported 6.0 heads?

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Old 05-17-2004, 02:21 PM
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Question Advantage to use unported 6.0 heads?

I have a G5X2 that will be going in my car soon and was wondering if it would be worth it to get a set of unported 6.0 heads (317 casting) to put on the motor right now and have them ported some time down the road. Would the 6.0 heads give an advantage to stock 5.7 heads or could they possibly hurt performance by being unported? Thanks for the help.

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Old 05-17-2004, 02:23 PM
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Originally Posted by Brandon98TA
I have a G5X2 that will be going in my car soon and was wondering if it would be worth it to get a set of unported 6.0 heads (317 casting) to put on the motor right now and have them ported some time down the road. Would the 6.0 heads give an advantage to stock 5.7 heads or could they possibly hurt performance by being unported? Thanks for the help.

Brandon.
I would say yes, you will loose compression, but gain flow. I would say the flow gained would out-weigh what was lost in compression.
Old 05-17-2004, 02:39 PM
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Thats what I was thinking.
Also, what are the stock valve sizes for the 5.7 and 6.0 heads?

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Old 05-17-2004, 02:52 PM
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Originally Posted by Brandon98TA
Thats what I was thinking.
Also, what are the stock valve sizes for the 5.7 and 6.0 heads?

Brandon.
Same....same... They are 2.00 and 1.55
Old 05-17-2004, 06:14 PM
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Originally Posted by ackman
I would say yes, you will loose compression, but gain flow. I would say the flow gained would out-weigh what was lost in compression.
I disagree. The resulting compression ratio on a stock shortblock will be 9.46:1. The loss of compression will hurt performance. I don't think the slight difference in flow will offset this loss. Why go through all of that work and expense for stock 6.0 heads?
Old 05-17-2004, 06:26 PM
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Expense would be the same in the end, I just dont have it all upfront to get them ported right now. The reason I ask is because I can get a good price on a set of bare 6.0 heads right now that I would use as cores for porting later on.

If the loss of compression is the problem, could I just mill the heads a little right now and fix it? Would I be able to mill them enough without have to worry about flycutting the pistons?




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