i found out today that series one, series 2 and fiesta turbos all have different pistons. but the same rings.

i had a series 2 and a frst piston together today and noticed a few differences. the series 2 has a larger crown and deeper valve cut outs.

my question to you is could you use erst pistons in a frst block?
i dont have a micrometer so i couldnt measure from the top of the piston to the bottom of the rod on each to compare them.

just from seeing the larger crown on the erst piston i thought if you put that in the frst block would it increase the compression ratio?


also just wondering, do erst and frst engine have the same compression ratio?