Pistons specs question for 340 build

70Hardtop said

Yes so did I, but they are ADDING to the volume, not taking away, so the CR goes down. I didn't know that the other manufacturer uses a positive for theirs, seems like there's no standard for that yet. As you say (and I didn't know until you said it) the 5 is 5cc for the valve depressions and 16 is for the dish. The only minus value should relate to the CR, but it's not, so it seems strange they use it for cc

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Well, there IS a standard and I can tell you what it is.

When you actually SIT DOWN and manually figure compression ratio using formulas, instead of online calculators, you must use the positive and negative numbers as I outlined. If you reverse that, your results will not be correct. That's why I make the argument. If you use the online calculators, just make sure which way they use those figures and that you are entering them correctly.