grendelFFR

Hi all,
I'm in the process of doing a complete engine rebuild on a 97 Cobra motor, and I'm changing the pistons out for a Mahle PowerPak. I already have the pistons, but I bought them from a friend who no longer has the instructions (they were new, but the pack was opened). Anyway, does anyone know what the ring end gaps should be? Are they the same as stock? (.03974" for compression rings) Also, are there any other special instructions for these pistons (like which way the rings go or clean instructions, etc)?

thanks in advance!

NR

livefast1

what kind of build is this n/a, forced induction, shooting for high numbers?

grendelFFR

It's just a straight, naturally-aspirated, stock rebuild with all tolerances very tight (blueprinting). I'm just shooting for 350hp with some tuning and a few bolt ons..this is going into a 2000lb FactoryFive roadster, so it should be plenty for now. The type of rebuild isn't really that important I wouldn't think; I'm just looking for the piston manufacturer's (Mahle) specs on what they would want the ring end gaps to be. I could just go with the stock piston specs, but I'm afraid the ring material is different, therefore having different expansion rates and require a different gap.

dennis_112

Dont hate me if I am wrong but I think .004 per inch of bore NA, and .006 per inch of bore for superchargered is a good starting point. And if my memory serves me right, standard bore is 3.552, if I am right it would come out to .014 ring gap. Sorry if I am wrong doing this from memory and computer calulator.