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Old 08-26-2014, 01:16 PM
mtntop1 mtntop1 is offline
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Cubic Inches

If I bore a 302cu in .30 over what will the new cubic inches be. Also approximately how much torque improvement.
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Old 08-26-2014, 02:06 PM
85e150six4mtod 85e150six4mtod is offline
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That gives you a 306 and probably no measurable difference in power. You gain 4 CI, but you lose just a tick of compression.

Is this just a clean up bore during a rebuild?

http://www.wallaceracing.com/cid.php
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Old 08-26-2014, 04:46 PM
xlt4wd90 xlt4wd90 is offline
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Wouldn't boring out the cylinder GAIN a tick of compression? It's squeezing a little more volume into the same combustion chamber.
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Old 08-27-2014, 12:40 AM
85e150six4mtod 85e150six4mtod is offline
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Bigger space and VE is not 100%. Marginal VE is even lower. Plus you usually have a bigger head gasket gap.
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Old 08-28-2014, 11:07 PM
SDDL-UP SDDL-UP is offline
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Yes, you gain compression by increasing the bore.
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Old 08-29-2014, 12:39 AM
85e150six4mtod 85e150six4mtod is offline
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Checked a couple of static CR calculators. You are correct, you get a bit of a boost in CR with a bigger bore, all else being the same.

Dynamic compression....not sure, but given the marginal volumetric efficiency, I don't see how you gain cylinder pressure while running. I suppose there is a standard, known calculation for that as well, but I don't feel like looking it up and proving myself wrong again.

Op hasn't been back yet.....
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Old 08-29-2014, 12:39 AM
 
 
 
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