Piston direction 3.3liter 930

[millhaus]

I just want to confirm the correct piston orientation. My 930 piston has a mark on it that looks like it is supposed to represent the flywheel and crank to help orient the piston correctly.

Is that correct? Sorry for the crude sketch.

[Flat6pac]

The squiggle orients toward the flywheel.
Bruce

[millhaus]

By "squiggle" do you mean the vertical line that looks like th eside of the flywheel connected to the crank? In this case the fly wheel is to the right?

[Flat6pac]

The whole stamping refers to the flywheel. The stamping goes the flywheel side of the piston.
Bruce

[Flieger]

So on the opposite bank's pistons, the vertical line should go toward the flywheel but both banks have the whole mark on the flywheel side of the piston. They just used one stamp, rather than "handed" pairs.

[Walt Fricke]

I'm not a 930 guy, but this must mean that the 930 piston top doesn't have valve pockets or funny asymetrical shaped domes like the CIS pistons have. Otherwise you couldn't use a mark which was the same on all pistons to orient both banks toward (or away) from the flywheel.

930 pistons have a symetrical concave top, rather than any kind of dome? To keep the CR down?

This must also mean that the 930 pistons have offset wrist pins, and Porsche wanted them all to be in the same relationship to crank rotation. Probably for anti-slap.