Cylinder Ring Replacement on Aulsil Jugs

[porschedude996]

Ok, I know I’m opening an old can of worms. I checked and mine are 10 fin. So that makes them Aulsil. There is no ring ridge and the bore surface has a strange almost clear gray anodized look to it. Not what I’ve ever seen. I see posts that say don’t even take the pistons out of the cylinder. While others say they can be re-ringed.

Unfortunately I did not perform a leak down test, nor a compression test prior to disassembly. I could do a top of the bore and a bottom of the bore leak down test on one bank since the heads are still on and the rockers are removed. That would give me a general idea of the next steps. In addition, I have cover plates on the ports, so I would be testing the rings only.

I just performed a leak down test on one bank and they were 82/100, 90/100, 85/100 with the pistons at the bottom of the stroke. I then did the test at the top of the stroke and came up with the same. I did hear leakage around the spring seats. The leakage was on the intakes. Sounds like the valves are not sealing properly. With a cylinder head rebuild the leak down numbers should come up dramatically.

Any thoughts?

[mikedsilva]

Originally Posted by porschedude996

Ok, I know I’m opening an old can of worms. I checked and mine are 10 fin. So that makes them Aulsil. There is no ring ridge and the bore surface has a strange almost clear gray anodized look to it. Not what I’ve ever seen. I see posts that say don’t even take the pistons out of the cylinder. While others say they can be re-ringed.

Unfortunately I did not perform a leak down test, nor a compression test prior to disassembly. I could do a top of the bore and a bottom of the bore leak down test on one bank since the heads are still on and the rockers are removed. That would give me a general idea of the next steps. In addition, I have cover plates on the ports, so I would be testing the rings only.

I just performed a leak down test on one bank and they were 82/100, 90/100, 85/100 with the pistons at the bottom of the stroke. I then did the test at the top of the stroke and came up with the same. I did hear leakage around the spring seats. The leakage was on the intakes. Sounds like the valves are not sealing properly. With a cylinder head rebuild the leak down numbers should come up dramatically.

Any thoughts?

I've not re-ringed Alusil yet. Haven't found a client willing to take the 'risk'.
I did reach out to a few other builders who have done more engines than I could ever attempt and a couple did say they had not had not been successful with re-ringing.

I'd be inclined to put it back together as it is.

It's odd that we 911 people have such a hard time with it.. since the 944 crowd have nothing but Alusil.
Incidentally,. I pulled apart an alusil motor a while ago that had travelled 300,000kms and the rings and bores were in amazing condition. But the owner purchased new Mahle Nikasil cylinders and pistons to rebuild.

[porschedude996]

Thanks Mike, it goes against every grain in my body to not re-ring. But what I find truly amazing is the total lack of any ring ridge. Absolutely only carbon. If I go with the most conservative route, I'll clean up the piston crown and the outside of the cylinders and install.

[john walker's workshop]

I've re-ringed lots of Alusils. Don't hone them. Use the proper Goetze rings for Alusil.

[mikedsilva]

Originally Posted by john walker's workshop

I've re-ringed lots of Alusils. Don't hone them. Use the proper Goetze rings for Alusil.

I'd love to know the correct part number for rings to purchase for Alusil. Care to share?

Last I checked, I kept getting conflicting information when trying to choose which set to purchase.

[Zuffenwerker]

I’ve done 2 recent alusil sc engine rebuilds. Both high mileage engines with p’s and c’s that measure within spec. The first engine was a stock sc engine and it got fresh rings from deves (they also sell the correct ring) with no cylinder honing. It took a while for the rings to fully work and not burn any oil…it’s my own car. Took a couple hundred miles at least now it’s all good!
The 2nd engine was just finished a few months ago and it also was a stock sc engine with fresh rings but I honed the cylinders with an AO brm brush hone. The rings seated instantly. I was guided this way by one of the most famous Porsche masters of all time, I would recommend new rings and a quick hone even the Porsche says to never deglaze aluminum cylinders. Make sure the p’s smd c’s aren’t junk though - measure!

[mikedsilva]

Got a link for the correct rings to buy?

[john walker's workshop]

Goetze rings for Alusil, 08-320900-10

For Mahle 08-320000-10

I don't recommend Deves rings. Take too long to seat, if ever. And again, don't hone the cylinders, just check for round, taper and scoring.

[porschedude996]

Thank you John the p/n’s. I do see some scuff marks on the piston skirts. One is pretty deep. Deep enough to collect the brown deposits from the crankcase area.

[Henry Schmidt]

Originally Posted by john walker's workshop

Goetze rings for Alusil, 08-320900-10

For Mahle 08-320000-10

I don't recommend Deves rings. Take too long to seat, if ever. And again, don't hone the cylinders, just check for round, taper and scoring.

All good information.

[Rosco_NZ]

Alusil cylinders can be Nikasil treated.

[porschedude996]

After I read the comments, I elected to pull the jugs and check out the pistons. All were somewhat scored. I couldn’t believe how impacted goo’ed up the oil control rings were. I’ve elected to buy some euro nickies.

[Jeff Alton]

We have re-ringed plenty of Alusil motors. We do have them lapped via the proper Sunnen process. Never had an issue, but yes, as others have stated, get the correct ring pack.

Cheers

[mikedsilva]

Originally Posted by john walker's workshop

Goetze rings for Alusil, 08-320900-10

For Mahle 08-320000-10

I don't recommend Deves rings. Take too long to seat, if ever. And again, don't hone the cylinders, just check for round, taper and scoring.

I see the first part number correlates to a 3.5mm oil control ring and the 2nd part number correlates to the 4mm ring. is that the only difference?

My understanding was the 4mm packs are for the early 3.0 and the 3.5mm packs are for the later 3.0 and 3.2 but that they were all for Nikasil barrels... Happy to be corrected.

[boyt911sc]

I have re-ringed many SC motors with Alusil cylinders for more than 25 years with no problem. The ‘78 SC (track car) has logged more than 30K miles before I retire from going to the track. It is still running flawlessly even up today. The myth about re-ringing Alusil cylinders has been busted many years ago. People have been installing new piston rings on their Alusil cylinders for the past 20 years and never been disappointed.

With the available technology of re-coating Alusil cylinders, re-ringing Alusil cylinders become even more popular and lower the cost of engine rebuilding overhead expenses. Just another satisfied re-ringed Alusil cylinders user.

Tony

[Rivet]

I have re ringed alusil bore before but I have always lapped the cylinders to get them ready for the new rings.

It requires either an AN portable sunnen hone that can be driven by a drill or an AN adapter for a Sunnen horizontal hone, and specially designed felt "stones" along with a paste made by Sunnen to relieve any transferred debris and aluminum from the bore surface. The surface when done is a uniform matt finish.

They also offer alusil specific stones that I have used before to adjust piston to wall clearance for special applications that are then followed up with the felt and paste.

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