Thread: 6x-4's or 8s?
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  #26  
Old 10-14-2021, 08:58 PM
'ol Pinion head 'ol Pinion head is offline
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Quote:
Originally Posted by steve25 View Post
So if you go .030” over to a bore of 4.150” and then to the 4.250” crank, when you use the -4 head at 91 CCs , then by my math using common numbers for deck height, head gasket volume and valve notch volume I come up with a compression of 9.39 to 1.

If you run the -8 head at 98 CCs then your at 8.88 to 1 in compression.

With that 4.250” stroke crank every 3 CC change will change the compression ratio by 1/4 point basically.
Since the early 90's have always had 455 block surface squared & zero decked. That will add near an extra 1/2 pt of static CR.

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