the pistons are NOT the same...the 2.0 has 10:1 compression and the 2.3 has a 9.7:1 compression...the bores are the same, but the piston have different compression ratios...the 2.0 has a slight higher to compensate for the less power
I haven't read anything yet regarding any of this information I'm just making a generality.
But typically manufacturers change the compression ratio by differing the size of the combustion chamber in the head and keep the same pistions. If its a "bolt on" change sometimes they do it by changing the piston.
The compression ratio is a function of how much power you want out of an engine and the end combustion temperature so it affects the combustion products you are going to get so it is sometimes altered to meet emissions standards.
I just got done doing all the little self tests in my engine dynamics and theory books. I feel like I know everything, but it seems that the pistons would differ because of the higher compression on the lower output motor and a lower on the bigger. Because if it was just rod length then you would want to think the opposite. Unless*** There is a huge possibility that the 2.3 head just has more cc's in each chamber than the 2.0 resuliting in a higher output, yet lower compression.
compression ratio is a function of the volume difference between top dead center and bottom dead center. Whatever is leftover could be from the piston difference or from the shape of the combustion chamber.
A forum community dedicated to Mazda 3 and all Mazda vehicle owners and enthusiasts. Come join the discussion about MazdaSpeed performance, modifications, classifieds, troubleshooting, maintenance, and more!