Im not allowed yet to post pics, maybe someone can re-post my link and embed it so everyone can see.
https://drive.google.com/file/d/0BwGUz3GGZ1bASFVxb3hub0Y4T1U/view?usp=sharing
the picture is the job card for the Arias pistons
the job card says 8.6:1 compression ratio, so that might answer the question
***Thread jacking question*** in the picture the piston on the left is the KA24e ARIAS forged piston (3520300) and on the right is a Nippon NPR KA24e hypereutectic piston(10-600). Notice the dish on each one; it seems like the Arias has more dish which is why i am still confused as to what it may be. The NPR piston actually says 2.88 on the box but the dish is a teeny tiny bit. Doesnt "seem" dished at all.
Is it the case, that at the end of the day they are both 8.6:1 compression ratio while the design of the more expensive forged pistons are designed to work safer under boost than the cheaper NPR "dish"? That's my guess, what gives, can someone explain this to me,