SS/SZ Pistons vs "Normal Pistons"

Hi Björn,

my information says 1300 normale = 8.5:1 compresion ratio
1300 veloce = 9.1:1 compresion ratio
1300 SS = 9.7:1 compresion ratio

Hope that is of some help to you.
Have a nice weekend,
Nick

There were just today a set of NOS Mahle Normale pistons (8.5) on ebay that I got outbid on. The crown shape looked quite a bit lower, with resulting smaller valve cutouts, than what Centerline shows on its site for 9.1 "Normale" pistons.
Andrew

Aside from the compression ratio and piston crown shape, I think the Veloce pistons were also forged instead of cast (but I'm not positive about this point).
Jim

Regardless of what piston you are using (Dome shape), if you are rebuilding an SS (1300) or SZ engine I would chamfer the top edge of the piston about 3-4 mm to relieve the edge as the engine block has been shortened on these engines. If you have the old pistons, you will see how much was removed. I would then "clay" any replacement pistons to make sure there is the correct clearance in the valve pockets. Your machine shop will tell you how much is satisfactory accounting for heat expansion.