Alusil cylinder de-glazing/plateau honing

FL911 · 03-10-2008, 07:35 PM

I am sure there are a BUNCH of you in my shoes right now.....broken head studs, tore down the engine to find Alusil cylinders right? RIGHT! I have read so much on this subject......everything from use the old Alusils for paper weights to go ahead and re-ring the old pistons and use the Alusils or to de-glaze or plateau hone the Alusils with a silca carbide "grape/flex/ball hone!

Some say not to use any of this old stuff and spend 3K on new stuff. Well I don't know about you but I have kids to raise!

What in the *&@# is the correct thing to do for those of us that can't buy new stuff?

I want concrete information on if these Alusils can in deed be used with a good success rate!!!!!

Is anyone with me on this or have I been dreaming all of this up?

Thanks for any input and sites to visit to purchase this honing material.

Alan Cottrill · Alan Cottrill's Garage

The first thing you should do is have the Pistons and Cylinders measured by an experienced machinist to see if they're even close to within spec in ALL regards (diameter, taper, round, ring groove clearance, ect...). You can't make a good decision until you've done this. Then it's up to you. There are a few well documented threads about different ways to prepare them to be reused. Pick the one that makes the best sense to you and fits your skills/resources and let us know how it goes.

jmohn · jmohn's Garage

Check with the 944 guys, those engines are all "Alusil" and quite a number of them have been successfully rebuilt. IIRC, the consensus was, if the bores are not damaged leave them alone. Of course that opinion may have changed, the last time I researched 944 repair procedures (951 in my case) was 7 or 8 years ago.

Jerry M
'78 SC

JBO · 03-11-2008, 06:47 AM

If the mileage is not high and they measure within spec, you can reuse them as-is, which is what I did a few years ago, but my engine only had 64k on it at the time. Some have reported success with the "sunnen" system and re-ringing, but this goes against the conventional wisdom.

MarKoBrow · 03-11-2008, 07:10 AM

I took the advice of Charles at LM Engineering and had all my cylinders trued and had them plated with Ni-com from US chrome, Then I had them honed with a diamond carbide grape flex hone. Now this is not exactly what Charles would have done, I think he would have chosen another plater and would have bored them out to 98mm and got custom JE pistons made.

Superman · 03-11-2008, 07:38 AM

There is a LONG thread on the Engine Rebuild forum. I think it is entitled "Re-Ringing Alusils" or something like that. MORE than all the information you need, including in-depth discussion of the technology of both Alusil and Nikasil cylinders. Read it.

I re-ringed mine with terrific results. The secret? Cleaning. Deep cleaning. The "business surface" of Alusil cylinders is exposed silicon. The silicon needs to be re-exposed. DO NOT HONE. Honing will achieve the opposite of what you need. The carbonized buildup between the silicon chips needs to be dissolved away.

And of course, they need to measure up. At 183k miles, the most wear I could find was .0015". That is NOTHING. They were well within factory spec. So were the pistons. Clean the piss out of those cylinders, and do not baby them at startup.

stevemfr · 03-11-2008, 01:07 PM

Hey Frank,
do a search under the username CNavarro. Charles is the owner of LN Engineering - they make the 'Nickies' cylinders - and has outlined very clearly what and how the potential options you have are in several threads (he's a good guy - not just intent on selling his cylinders).

Superman · 03-11-2008, 01:54 PM

I'm not kidding. Here is the link. After reading through it, ask yourself whether any additional information could even be helpful. The thread is in its 27th page:

Re-ring Alusils?

cnavarro · 06:36 PM

I'll just clarify, I don't use US Chrome. Never have either. I use Millennium, but same idea. Thanks for the kind words though :-)

I've even gone as far as to machine the CE groove into a ledge and fit a copper sealing ring in, allowing alusil cylinders to be bored out to 98mm and fitted with new pistons. A few hundred more, but seeing as core alusil cylinders are so plentiful and cheap, it's a good alternative to they typical bored out and replated 3.2 cylinders.

Laneco · 03-11-2008, 07:23 PM

Frank,
If done properly it works. Very very well. I'm driving one every day that John Walker had done (re-ring pistons in alusil cylinders). In fact, I'm taking a nice trip next week with it.

angela and BUTTERS da Uber-beater!

MarKoBrow · 03-11-2008, 08:17 PM

Hey Charles, I used US chrome because of location, they have a plant in Norristown, Pa. that does industrial hard chrome plating for me, so it was easier to use them as a provider of this service ( although I now understand they sent them to Wisconson to have the plating done) but none the less they look good and work fine..... Thanks very much for the advice and when I am ready, I do want to send you a set so I can get some 98mm's done with high compression JE pistons ..........we'll talk soon

FL911 · 03-12-2008, 05:42 AM

Thanks for all of the input! I read 9 pages of the original post and have learned a lot.
I have come to the conclusion that Alusils are in fact reusable if in spec. and in good condition say under 185,000 miles in some cases (superman).
If the crosshatch pattern is still visible along with the teeny tiney (macroscopic) silica impregnations then they can be re-ring successfully or (if in spec.) they can be de-glazed using a 180 grit grape/flex hone made of silica NOT STONE or by using felt pads and a silica compound.........along with many other ways that are much more expensive like the SUNNEN machine etc.
I will continue reading, it is nice to hear that this can and has been done successfully in many cases.

1982911SCTarga · 09:57 AM

The part number for Alusil piston rings for an '80-up SC is 93010398500.

If you look at this thread (it's a short one) and read the workshop manual chart comparing Nikasil and Alusil pistons, cylinders and rings, you'll see that there are significant differences between the ring sets used.

For the record, I've got Alusil pistons and cylinders in both my '82 and '83. I'm on the fence about re-ringing my '83's engine (I'm just getting the heads off now and have yet to spec things).

Brian

Superman · 03-12-2008, 10:28 AM

The rings I used were the ones JW recommended. Goetse?

I would not agree that you should hone or use any abrasive on the business surface of Alusils prior to re-ringing. The method I used was to get them ridiculously clean. Honing them runs the risk of losing the silica surface. Cleaning them exposes that surface. Be aware that Alusil technology involves manufacturing them with aluminum that has silica in it, and then etching the aluminum away in order to expose the silica chips. Again, the most wear I could find at 183K miles was .0015". That means no wear. It means the original surface was, basically, still there. The cylinders wore the rings, rather than the other way around. My rings were very worn. The ring gap was at the edge of factory tolerance. The rings had worn. The cylinders had not. And again, one more time, if you hone these cylinders, you run the risk of taking the silica surface down to the aluminum. That's not going to work.

1982911SCTarga · 03-12-2008, 10:34 AM

Is Goetze an aftermarket supplier of rings for both Alusil and Nikasil pistons? The cost is one-fourth of the OEM Alusil rings.

Brian

1982911SCTarga · 03-12-2008, 10:50 AM

More info here. Is it correct that the same Goetze ring set can be used to re-ring both Nikasil and Alusil pistons?

Brian

1982911SCTarga · 03-12-2008, 04:28 PM

I've been searching this board and all threads seem to go dark on this OEM-Schmidt vs. OEM-Goetze question. Are Alusil pistons re-ringed with the much more expensive Schmidt ring set? I, for one, can understand why but there's a real lack of clarity concerning the fact that Alusil piston rings and Nikasil rings are different animals. I don't think Wayne's engine rebuilding book mentions this. What's the story?

Brian

1982911SCTarga · 05:20 PM

OK, the answers, hints and clues appear to be in the earlier referenced multipage mother-of-all-Alusil-re-ringing threads.

Brian

FL911 · 03-12-2008, 08:48 PM

I like most of you spent the better part of 3 hours reading that thread also ......then boom it ended like a bad soap opera! I hope it is not dead totally, I was waiting for the results of the "Jack the Snowmans" process with the grape hone or silica hone. I am right in the middle of this rebuild also and want to know more and more on this process or should I go with the AN-30 paste and felt pads from SUNNEN?
RONIDONE, SNOWMAN and the rest of you........come back!

ed mayo · 03-12-2008, 10:01 PM

It has been my experience that rings for nicasil and alusil are NOT interchangeable. On the advice of a supplier we tried that once, the engine smoked badly. The second tear down was now for free, and was done with the expensive, correct alusil rings from Porsche. Needless to say that was the end of the smoking. My advice, buy only alusil rings from Porsche (no one else has compatible rings to my knowledge) lightly clean the cylinders with naptha soaked scotch brite pads, thoroughly clean cylinders with oil and clean rags. Any ring other than from Porsche is a gamble.