ok thats intersting.

I know porsche has different bore sizes, its listed at 100mm but they can range from 99.980 or so to 100.00mm in 3 steps i believe. I wonder if you have the higher value, as i do in my car. There is a number stamped into the block above each cylinder inside the V of the 928 engine. I wonder if the standard rings are made for the smallest of the available bore sizes and thus they are out of spec for some blocks that have a slightly larger bore.

I was really only going to go with OEM Goetz, i dont want to pay 4x the price for rings, how far out where they. I dont know the specs for proper ring gap, were they double?

If Goetz are slightly too small, i wonder if the Deves rings would be a better fit. I have heard Deves is lower down on the quality scale then Goetz, but I could be completely wrong in this.

Thanks so far for all the posts. Please keep them coming, no one on the 928 board had much to say about this stuff, i am glad i asked my 4 cylinder brothers.

 

The factory end gap spec on new 951 rings is: 0.20-0.40mm 1st ring, 0.20-0.40 2nd, 0.30-0.60 3rd (oil scraper)

Fact. Spec on used rings is (wear limit): 0.80 1st, 0.80 2nd, 1.20 3rd.

My measurements on the new Goetze rings were 0.305-0.432 1st, 0.508-0.559 2nd, 0.432-0.483 3rd.

So although the new rings did not all meet factory new specs, they were well within the wear limit. So I installed them, and have not looked back....

And interestingly, all the 1st and 3rd rings I took out of a 50k mile motor were above the wear limit. But the 2nd compression rings were within the factory spec for wear limit, two of them were tighter than the new Goetze rings.

I cannot comment on Deves quality versus Goetze. I do know that Goetze rings are very commonly used rebuilds, so although I found a slight deviation in the specs, I think they should be ok. Just make sure you check them.

 

Removal and reinstall of the crank girdle is not trivial. It must be sealed properly with the Loctite or you will have oil pressure problems due to the main oil gallery being intergral with the girdle. Also, I had problems with the oil pump mating surface - too much of a step for 'stoning'. I ended up cutting a brass shim to flatten out the mating area.

 

I pulled the first piston and put the rings back in the bore to check end gap, and i get .5mm or there abouts for the 1st and second rings.

I am now debating wether or not i should even replace these. Mind you the car has 110K miles on it.

Is there more to a rings condition then simply the end gap?

 

i would like to know too, im in the same situation right now (deciding weather or not to replace my rings) except my engine has 200k on it. i will be checking the gap tomorrow