Don’t get confused here. I think DTD is correct. What it’s telling you is the actual volume of the combustion space (actually the chamber because the piston is the actual bottom of the chamber) when the piston is at TDC. I hate maths so I keep it simple.
If you have a 100 cc chamber, and a 10 cc dish piston and the piston is down the bore .020 and that adds another 10 cc’s you’ll have a total of 120 cc’s of volume with the piston at TDC.
That’s what DTD is telling you. And without seeing all your numbers no one can say for sure if DYD is correct or not. I suspect it’s close but I don’t know what inputs it asks you for.
