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Discussion Starter #1
So based upon the info I acquired plus help from others I typed in all the info to figure out compression of a set of pistons...what I came up with and what they are is 2 totally different things..maybe I typed something in wrong? Any1 able to chime in?

172440
 

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89.50* bore?
 

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Piston I’m referring to comes out to 89.05mm or 3.506” even if it was 89.5 the compression would be even more...these should not be 11 plus compression lol
 

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I don't think our pistons come up to the top of the cylinder bore so there is more than the head volume as the minimum compression volume.
For our 9.5:1 and 2488cc we should have a compression volume/cylinder of approx. 65.5cc
With the head volume measured at 55 does the gasket thickness allow for this extra ?
Also I thought the stock pistons were dished not domed.
 

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Discussion Starter #5
I’m not referring to stock pistons I’m referring to a set I have here I posted a diff thread on them...as for the 55cc I was told that’s the volume but obviously I don’t know what it is and you say 65 lol
 

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Even then, IIRC we get the same comp when we swap over to the 2nd gen pistons or do we not? I have to wonder now if what was said in that thread I posted in your thread if that was correct for the first gen head as I only did the 2nd gen head.
 

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if that is true, that would account for the difference, there is a differnce in the combustion chamber that might account for "10cc", plug in 65 and see what happens.
 
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