The "tdc method" does not solve for dish/dome volume. It combines the dish/dome volume with the deck clearance.


Using previously mentioned perfectly flat 4.00 piston.......

The fill down for 4.00 x .500 is 103cc.

If you measured the .500 from tdc, and observed a fill volume of 98.9cc, what would you call the dish/dome volume?

The piston itself has zero volume.......the fact that it's sitting above the deck .020 is where the reduction of 4.1cc's comes from.

Which way you do the math won't change what the actual cr is, it just makes more sense to me to use the actual dome volumes and deck volumes instead of combining them.

Either way will work, just make sure if you're comparing notes with someone else that everyone is on the same page.
As this thread has shown, when you're not.........the results can be way off.