Re-ring Alusils?

[VFR750]

Replate and new je pistons used to be $1600 with trade in used cylinders. Now $3000.

I had to go that route because my piston ring clearance was .011”

[mikedsilva]

Originally Posted by VFR750

KS is Kobel-schmidt (Schmidt) and they are Alusil

I used scotchbrite pads, tie-wraped onto the stones of a spring loaded hone.

Per the Porsche PET

(SCHMIDT) --> Alusil
930 103 963 00 Set of piston rings -79 SC (4mm oil scraper)
930 103 986 00 Set of piston rings 80- SC (3.5mm oil scraper)

Pelican has them both in stock:

https://www.pelicanparts.com/More_Info/93010396300.htm?pn=930-103-963-00-M42&KeepHeader=Y

https://www.pelicanparts.com/More_Info/93010398600M42.htm?pn=930-103-986-00-M42&bt=Y&fs=0&SVSVSI=0807


For reference the (MAHLE) --> Nikasil
930 103 967 00 Set of piston rings -79SC
930 103 985 00 Set of piston rings 80- SC

I think I am getting some different numbers to you...or perhaps, I am reading the PET differently to you.
Here is a screenshot from my parts listing.
The way it is printed is a little misleading.. they list the Mahle options for Nikasil up the top.. then there is only 1 option for Alusil (SCHMIDT) 930 103 967 00 at the bottom.
I contacted my Gen Porsche agent and they confirmed the 930 103 967 00 is the SCHMIDT option and the rings are available from Germany, but you actually have to order the rings separately. I will add another screen shot of the quote.

[mikedsilva]

Here is the excerpt of the quote from Porsche
You might be able to use the individual part numbers for Alusil rings.

[VFR750]

Hope I did not read the pet incorrectly.

[VFR750]

You are correct.

I have an older copy and the way the rings are listed I read it wrong.

Sorry mike.

[mikedsilva]

Originally Posted by VFR750

You are correct.

I have an older copy and the way the rings are listed I read it wrong.

Sorry mike.

no issue.
I thought it best I list the screenshot so others can reference it too.
It is confusing how they printed it.. a couple of spaced lines would have helped separate them!

[HondaDustR]

Originally Posted by mikedsilva

I just read this entire thread.

I've come across my first Alusil cylinder 911 engine today..

At this point, cylinders appear to be in excellent condition. Pistons are also in quite good condition.

Was there a final consensus on using a grape hone? It was mentioned by Snowman several times.. (probably more) but he appears to be the only one that uses it.

My cylinders do not have any visible cross hatching and even the part at the bottom and top of cylinder also does not have any cross hatching. I'm tempted to just use scotchbrite and soapy water with strong detergent.

However, can I simply use the Goetze or Mahle rings as listed on this site? The description in the Goetze rings listing, says they are for use in both Mahle & KS pistons so does that mean they can be used in both Nikasil and Alusil cylinders?

Here is a pic of the pelican parts listing.. I don't understand the difference between the 2 Goetze listings.. same description, same thickness rings, but different part numbers?

Woah, a notification for this thread pulled me out of Porsche forums hibernation...lol

I believe to never use an abrasive stone hone of any kind unless it is explicitly indicated for use with Alusil, which I think such a brush hone might actually exist in the BRM catalog...I'd have to check.

I had excellent results with green scotchbrite tied to a spring arm hone, but in developing my method on an old block, I found that a 20 weight mineral oil made a better surface with more consistent and slightly smoother/finer appearance than soapy water. A dedicated honing oil may work better still. Hone just enough to dull the surface evenly and a "slight" crosshatch will become evident, and will largely go away after lapping. If you are producing pronounced crosshatching, either you are honing too much, using too coarse a pad (green is ideal), using excessive pressure (my spring arm hone pressure was strong enough for good finish at maximum spring setting, but an alternate tool might have a stronger spring action that may need adjusting down), using incorrect or insufficient lubricant, or pads are contaminated with debris.

I read of some people running successfully on just the scotchbrite honing, but I was able to source the AN-30 at the time and it produced a very promising dull grey chalkboard like finish when done. It was very important to get the right mix of mineral oil and paste on the cylinders so that it was fluid enough that the felt could slide it across the cylinder surface and abraid the surface without the pads just skating over a thick layer that isolates the honing action from the surface as it did if applied straight out of the can with no oil to dilute. I found the AN-30 stage to be automatically self limiting and beyond a certain point (somewhere in the 60 to 120 seconds range) did not make any further difference in finish but also no apparent further finish change or degradation if operated beyond the needed lapping time, within reason.

Again, Alusil should show at most light to non existent crosshatching or else it was done incorrectly in some way and service lifespan may be compromised! Worn in cylinders will be perfectly smooth and should show no crosshatching at all, unless they were incorrectly honed. The microscopic voids between the silicon particles created from lapping are what holds the lubricating oil the same way crosshatching does for an iron liner, which is why I would further recommend not skipping the lapping and not experimenting with incorrect abrasives for lapping if possible.

I used Deves rings in the 944 engine I rebuilt, and they were unplated cast iron rings if I remember correctly. I think Nikasil needs chrome plated and Alusil needs unplated cast rings, but that is only anecdotal memories from old research. I put about 70,000 miles of daily driving miles on the rebuild with spirited use of the tach at every opportunity and oil consumption was better than 1 qt/4000 miles after break in, declining only to about 1 qt/2500 miles additionally with leaking AOS seals before I retired the car. The photo is of the cylinders from the engine with over 60,000 miles to fix a bad headgasket. The motor never smoked, even during break in, and was broken in agressively in the first 100 miles as is critical with fresh Alusil. The engine was sold off after parting out the car for unrelated reasons.





Good luck!

[SCadaddle]

I went through this 8 years ago with my 82SC with KS Alusil pistons and cylinders. Even back then, the correct rings were pretty much "unobtainium" and the consensus was even if I did find the correct rings, all bets were off if they would actually seat in the cylinders. I spoke on the phone with Henry Schmidt. He put me on to Don at EBS Racing in Reno. I wound up sending EBS my KS pistons and cylinders, they had the cylinders Nikasil plated and honed to fit my KS pistons, and supplied the Goetz ring pack to fit. Parts, labor and shipping both ways wound up right around $1000. You might want to explore that option.

[mikedsilva]

Originally Posted by SCadaddle

I went through this 8 years ago with my 82SC with KS Alusil pistons and cylinders. Even back then, the correct rings were pretty much "unobtainium" and the consensus was even if I did find the correct rings, all bets were off if they would actually seat in the cylinders. I spoke on the phone with Henry Schmidt. He put me on to Don at EBS Racing in Reno. I wound up sending EBS my KS pistons and cylinders, they had the cylinders Nikasil plated and honed to fit my KS pistons, and supplied the Goetz ring pack to fit. Parts, labor and shipping both ways wound up right around $1000. You might want to explore that option.

um
does that mean you are runing your iron plated Alusil pistons, in a Nikasil cylinder?
How did it work out?
Any issues?

[burgermeister]

I attempted re-ringing my Alusils sometime in 2011 or 2012, with partial success. I used Goetze rings, and I honed with the correct paste abrasive that is supposed to expose the silicon in the cylinders. Forgot what it was called ... I probably have the can someplace still, to be found next time we move maybe ...

I had marginal success - the rings sort of seated, but I still burned about a quart every 1500 miles with some track usage in there. Tolerable, but I wasn't happy with it. Eventually, for other reasons, the engine came apart again and got a set of Mahle Nikasils in the process. Oil consumption dropped to 1qt every 4000 miles.

[SCadaddle]

Originally Posted by mikedsilva

um
does that mean you are runing your iron plated Alusil pistons, in a Nikasil cylinder?
How did it work out?
Any issues?

um, absolutely. I don't know just exactly how much "iron plating" was left on a set of pistons that as far as I know had previously run for 154k miles as my car indicated. That's why I dropped the two names you might want to inquire with, Henry out in California and Don in Nevada. As far as any issues, I probably drive the car 2-3k miles a year and change the oil yearly. In between oil changes I've never used a quart of oil, maybe 1/2 to 3/4.

Basically it came down to this: Throwing the dice on a very pricey set of Alusil rings that were pretty much unobtanium with NO guarantees that the rings would seat wasn't in the cards. Buying a new set of Mahles was out of the budget. Having my cylinders Nikasil coated, honed and fit a new set of JE pistons was contemplated, but I was assured that the old KS pistons would be fine in the new Nikasil coated cylinders with the right set of rings.

[divakaranv]

still learning and doing my rebuild of the entire engine from bottom and top and will share my project shortly here.

[divakaranv]

i will share my project shortly and I did it from bottom to top