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Old 01-07-2019, 10:49 AM   #3
Homeoboxter
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Join Date: Oct 2018
Location: North Cali
Posts: 745
Garage
Quote:
Originally Posted by marsheng View Post
Generic answer.

Is there pressure buildup from the engine case breather, if not, rings are probably fine.
If the car is for high RPM, a slightly larger gap is ok as very little gas/air gets through the gap a such a short time.
Hasting Rings says 0.014 " per inch of bore.

I'm sure there will be after market rings for sale. Most ring widths today are roughly the same for similar size pistons. I haven't stripped a 986 motor but I presume they are nikasiled, so get compatible rings. Ie not for cast iron.

I have a 2.7 motor in the shed just waiting for some spare time to give it a full overhaul.
Hi,

Thanks for the answer. Unfortunately I know nothing about the pressure buildup bc I`ve never seen this engine run. I looked at a Haynes manual for my SAAB 900, based on that values the second ring is out of spec (SAAB uses Mahle pistons and rings as well, the bores are larger though, so I don`t know how accurate that is for a Porsche). Based on what you are saying it really depends on the bore size so it still might be good, I`ll check that out. My worry is mostly about the side rails for the oil ring, if I place them into the bore I can see through the ring and the bore.
Interestingly, you can buy aftermarket rings for all the other engines but not for the 2.5L. For my car the only option I found is to buy the originals, that cost around 2K so it`s out of the equation. I did some research and found that certain BMW rings are the same in size, I`m not sure those are good for Nicasil though..
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