We all wrestle with the high cost of Porsche engine parts. In the case of 911 cylinder studs, purchasing OEM studs can save quite a bit of money over high strength aftermarket replacements with high quality self locking nuts. However, those of you who really want to make the stud problem go away forever, should still weigh the fact that none of the OEM studs come with a guarantee against failure. Porsche does not provide any metalurgical data on any of their studs, and we have a collection of broken studs of EVERY part number in our shop. Without knowing the basic material characteristics.... no one can make an informed decision which stud is better than another one. You could buy 10mm all-thread, cut it to lenght, and it would work for a while..... The question is, "How long?"
There is no part of the Porsche that is the subject of more conjecture and hearsay than the studs.
We have tested brand new OEM studs with yield strengths as low as 120ksi, and others (of identical part number) that had a 17% difference in yield.
In engine service, all broken studs are FATIGUE failures. They may start at a tool mark, or from chipped coating corrosion,.. but the propagation from the starting point will still be from fatigue.
In reality, we all know there are very few things that are free. The extra $$ buys material, processes, and quality control that assure the stud will never approach its fatigue limit. The cost of doing this for an OEM manufacturer like Porsche is prohibitive on the production line. However, when you divide the number of pieces (72) required to make a full cylinder fastener kit into the cost, you may be pleasantly surprised at the unit $$ for an all USA AS9100 manufactured product.
You are really buying the assurance that the studs will never, ever, be an issue down the road, no matter how many miles you put on the engine. You will not find loose head nuts or worse when the covers are off for valve adjustment at 30K, 40K, or 200K miles. Heads will not be damaged by hammering on the cylinder top rim, and tough oil leaks become history.
Lastly, high strength studs are more critical to a daily driver than to a race engine. Fatigue can be induced both mechanically and thermally. In this application, the thermal growth of the all aluminum cylinders is the culprit. The expanding cylinder barrel puts a tremendous mechanical (tensile) load on the cold studs. Engines with frequent cold starts, and hard acceleration before full warmup, create the most severe fatigue cycle on the stud (far worse than any race engine).
Bill Ryan
Casper Labs, Inc.

Update. I don't have it all yet but ...

Several cylinders found out of round. Evidence of one piston and valve collision. One broken scraper ring. Some pistons worn. Evidence of prior cylinder swapping. They are aluysil.

Heads are out for new guides, all new valves and springs.

Question: Can you replace the rod bolts without new bearings and can it be done without breaking the rod to crank (i'll call it seal) to cap?

I'm trying to so this without breaking the case.

What are my barel-piston choices?

You can replace the rod bolts and use the old bearings if they are in good shape. Normally I'd replace them anyway as they aren't that expensive and that way you'll get the most life out of them. You won't be able to replace the bolts without pulling the caps out, they are in too stiff to do that. I'm not sure why you want to replace the rod bolts. If you have 3.0 engine the bolts will last forever. 3.2 engines had a rep for breaking rod bolts not earlier engines.

I'd try to buy a good used set of pistons and cylinders. I see two sets on e-bay at Rothsport in Oregon. Others come up for sale frequently on this sight. A good set of Alusils can be had for as little as 300 dollars. I got my last set for my racing engine that way and was even able to re-use the rings.

-Andy

The engine is a 3.2 for my Daughters 87 Carrera, not the SC in my signature line. I understand the confusion.