Re-ring Alusils?

[William Miller]

Goetze rings: #08-320900-10 (number on the box)
95X1.5 + 1.75 + 3.5 mm std.
These are the actual ring dimensions 95mm top ring 1.5mm middle 1.75 bottom 3.5.
The label also say's 911SC 3.0/3.2

That's what's in there.

[smestas]

William,

Thanks for that info.

My part # is a bit different (GOETZE 08-32000-10) but it does say for '78 to 79SC.

Measurements for the rings are also different.
1.5 / 1.75 / 4.0 ?

What year is your car?

[William Miller]

OK, mine is a Euro 83, but has the US 930/16 3.0 engine. 9.3:1 CR

[Nathan M]

I've got the Goetze catalogue here...

08-320000-10 for 3.0L for up to July 1980 (4.0mm oil ring)
08-320900-10 for 3.0/3.2L August 1980 onwards (3.5mm oil ring)

[William Miller]

I doesn't specify different rings for different Cylinder types does it?
Mahle / KS Alusil

[Nathan M]

No, as mentioned in a previous post, these rings are suitable for both, and the (single) Goetze part number interchanges to both Porsche OE numbers for Nikasil / Alusil. I've also confirmed this with the guy who designs the Goetze rings - he sits in the same office as me!!

[William Miller]

Now, that adds some credibility to the discussion!
What is his / their imput on the topic?
Any testing done or aftermarket research?

[Groesbeck Hurricane]

After reading alot of comments (especially from Superman and Big John Walker) on Alusil's I decided to re-ring. My budget was limited and I had managed to break two of the old rings in my own d@*& fault type of a way. The rings did not fully seat for about 5K miles. I only have smoke on start-up now when there is more than 50% of the oil fill range on the dipstick. And the smoke goes away quickly. Everything was nicely in spec and the motor only had about 100K.

[smestas]

David,

Did you break the fresh motor in slowly or aggresivly? Im just curious since you say you have smoke on start up.

[Rondinone]

I'm in the exact same boat. Compression varies by 3% for all cylinders, but valve guides are worn. I've decided not to rering as I only put 4-5k on the car each year. Plus, as some on this board have mentioned, why mess with something that's not broken? If I have to tear it down again in the future because the rings wear out, so be it.

Just my $0.02. Good luck,

[snowman]

Originally posted by Groesbeck Hurricane
After reading alot of comments (especially from Superman and Big John Walker) on Alusil's I decided to re-ring. My budget was limited and I had managed to break two of the old rings in my own d@*& fault type of a way. The rings did not fully seat for about 5K miles. I only have smoke on start-up now when there is more than 50% of the oil fill range on the dipstick. And the smoke goes away quickly. Everything was nicely in spec and the motor only had about 100K.

sounds like you need new valve guides and or valve seals. Did you renew them?

Also as I have previously stated, if you use a grape stype silicone hone on the cylinders you will see break in within minutes, not thousands of miles. Break in is always done with agressive, ie several full throttle accellerations and decellerations, followed by cautious driving for a thousand miles or so. This is necessary to seat the rings properly. The real key to breakin, besides the initial full throttle stuff is NEVER to let the temperature to get to high, no matter what. If the temps ok the engines ok.

[Groesbeck Hurricane]

Simon,

Aggressive break-in.

Jack,

I renewed the guides and seals. Could be I will find that is an issue when I take it down again to replace the new front seal that has already failed, probably self inflicted also...

[snowman]

David,

Did you use protection on the valve stems (valve rubbers) when you installed them?

These are the little capsuel shaped things the cover the grooves in the valve stem and protect the seals when the valves are installed. Not using them can cause the problem.

The problem being seeing smoke at start up or after sitting for a while. The smoke quickly goes away. This is a result of oil leaking down the valve stems when the engine is just sitting there. When the engine is first started and for a short while later the oil is burned and hence smoke. The smoke does not continue because the leak is to slow. Why worry?? Generally not to much of a problem but with high performance engines it may cause detonation, and consequently poor performance or if there is no knock detector, damage to the engine.

[Superman]

Goetze. In all my boastful descriptions of my successful Alusil re-ring job, I may have neglected to mention that I could see no visible cross-hatching in the cylinder. Again, wear was no more than .0015" and the cylinders were scrubbed/cleaned within an inch of their lives, and very little oil was used on the cylinder walls. One guy even recommended dry cylinder walls. This would probably cause the rings to seat for sure. The question is whether any rings would be broken in the process.

[Doug Zielke]

Originally posted by Superman
I may have neglected to mention that I could see no visible cross-hatching in the cylinder.

Jim is on to something here.
I don't think new Alusil cylinders are honed at all.
I suspect the silicon matrix is very thin, and honing will destroy it.
The Factory manual does not indicate honing Alusil cylinders is an option.

The set I removed from my engine had no cross-hatch marks. Even the area at the bottom where the rings don't touch, was the same way.

Until a bona fide expert posts here saying honing (with a "grape" hone, or whatever) is ok, I would either re-ring them as Jim did with his in-spec cyls, or have them re-plated with Nikasil.

[mtelliott]

What are used Alusil's worth? I'm doing a rebuild and picked up new P&C but still have my old. What are they in the board's estimation? I'm not going to give them away because they are a great teaching aid for my son for when he get's older on how engines work but if they had value, then I could always apply that money to something else I'm going to need like 8 x 16 rims. Thoughts? I saw a while back that Unclezak (sp?) got like $360 for his. I intend to put them up for sale on the board if people think they have value and if not, put them in a box and show my son when he get's old enough to question. He's two now so I'm thinking it will be a couple of years.

[Doug Zielke]

I replaced my Alusils with Mahles, and so, was planning to sell them. However, I'm now going to have them re & re'd with Nikasil first.

[snowman]

Originally posted by Superman
Goetze. In all my boastful descriptions of my successful Alusil re-ring job, I may have neglected to mention that I could see no visible cross-hatching in the cylinder. Again, wear was no more than .0015" and the cylinders were scrubbed/cleaned within an inch of their lives, and very little oil was used on the cylinder walls. One guy even recommended dry cylinder walls. This would probably cause the rings to seat for sure. The question is whether any rings would be broken in the process.

The cross hatch marks are extreemly important as they hold the oil that the rings ride on. No cross hatch, no lube, short life and lack of performance. Use an MG engine as the ultimate example of a useless engine block. The cross hatch pattern is there to begin with but they go away within a few thousand miles, due to the crappy metal the brits used, and the engine is due to be rebuilt within 30k miles.

I guarentee all of your cylinders had or have cross hatch patterns in them. If they do not the cylinders are worn past their usefull life. The pattern is put in there by the honing process, a necessary and essencitial step in producing ANY cylinder for an auto engine. Any special treatments, such as the silicone hardening still include the cross hatch pattern, because if it did not the rings would not have lubricaiton. If the original treatment, over 0.5 thousands of an inch deep, is still there, the silicone ball hone, which will not remove anymore than 0.05 thousands, or so, will not hurt it, but it will clean up the surface and put some additional, fresh grooves in the surface for the rings to seat to and to provide lubrication.

Again, honing, with stones, removes a lot of material, eg, with rough stones, several thousands of an inch, with medium stones, up to one or two thousands of an inch, with fine stones, up to one half to one thousands of an inch, and with plateau honing, less than 0.1thousands of an inch. Grape ball type hones are a plauteau hone type of process, a clean up of the junk metal, a final placement of grooves in the cylinder walls. These things are one of the "SECRET" ingrediants of NASCAR and other true racing engines. These are the things that are only recently being incorperated into producion engines, for smog reasons of course, but are the ones responsible for some of the very high performance numbers you are seeing now. They are NOT new however, racers have been using them for years.

If you want genuine Expert advise on these type of hones, talk to the company that makes them. THese people have dedicated their LIVES and LIVELYHOOD to KNOWING what their product does and does not do. They are engineers and have real test data to support their claims.

[Nathan M]

I have information here from KS regarding final honing of Alusil cylinders -"The honing process is carried out on a Sunnen CK10 honing machine. The first 3 stages (rough hone, finish hone, polish) are performed using different honing stones. The honing stones, oil and machine settings are all important for good results and are different for each type of cylinder (911,944 etc). The fourth and last stage is silicon lapping. Here the honing stones are replaced with felt pads. Silicon paste is applied to both the cylinder bore and the felt pads. No honing oil is used. The use of felt pads with silicon paste does not result in a measurable material removal. Silicon crystals are exposed by this process in the cylinder bore which results in a durable, wear resistant cylinder surface."

For the record, my (80k) motor has visible cross-hatch patterns in the bores.

[Doug Zielke]

Thank you, Nat!
A post worth printing out.

I'm still curious why I could not see any honing marks in my old Alusils.
Maybe they were just worn out, even though they measured ok (?)