Does anybody know what the piston ring end gap should be for new rings for a 996tt?


-Jason

 

It's basically a stock build, I had the heads ported and polished with Ferrea valves. A combination of Raceware and ARP studs with Pauter rods. We'll probably do a Cobb tune, with exhaust and your turbo's & intercooler's next year sometime. The pistons and jugs are stock 3.6, but purchased new rings. Any idea what the ring gaps should be?

-Jason

 

Did you pull these from Porsche? Those numbers aren't published and there is the problem with the 2nd ring groove which has a locating pin in it. The head of the pin is wider than the .0065 and is actually .057. The new rings will measure .027 which is considerably larger than .0065. I only ask as I have never seen Porsche publish the numbers and most of the time we all go to CP or other and the specs you posted would be appropriate for that since they don't have the interference with the pin. it's odd to be sure.

 

Anybody else?


-Jason

 

Can you measure the used rings you have and compare that with what Sean posted?

 

The old ones are all inconsistent

 

dump that stuff and have sean get you a set of cp pistons and rings with la sleeves. then build it old school like any chevy or ford motor build.

 

While in theory one would think this would be acceptable, however the variables are too many to get an accurate reading. The most obvious is bore wear in the cylinder. On the TTs there is a locating pin in the second ring groove that keeps the ring from walking around. Under boost the ring will rattle under that pin and cause the ring to groove out on the top. It's not a great design and causes uneven wear on the ring. The end result is there is no way to accurately read it. Porsche will not and does not publish the numbers. In their eyes you simply buy a matched set and move on. That or aftermarket. It is interesting that no one has uncovered a true spec for this. FWIW that also includes me!