Custom piston choices
 

I have a 1996 993 C4S with 3.6 Varioram motor. It has a prototech turbo conversion setup on stock internals. The setup runs 6 psi with 11:2 CR. The performance is awesome!! Approx 450hp on 100 oct.

I need to tear into the motor to address an unknown knock. While inside I am considering replacing the pistons. I like the response of the high compression low boost setup.

I know the JE pistons don't have the high silicon alloy that matches the expansion rate of the stock mahle cylinders. What choices do we have to have to best match the factory barrels?

I think its important to understand that the vast majority of piston makers (except Mahle) use the same Alcoa 2618 alloy for performance engines. Turbo applications should use either Mahle or a properly made 2618 forging.

LN Engineering makes their own cylinders which Charles claims to match the expansion rates of 2618 so that may be a good option for you. They sure stay round a lot better than Mahle's do in these sizes.

JB Racing also carries a group of steel insert cylinders that are good for turbo applications. LN is another good application. Charles can also give you some good parameters on what to run