Hasen't anyone just asked Porsche what they think? I would think their engineers would be able to respond to this question and an answer all could beleive would be made available to us.

Charles,
You are correct in your assumption that EBS's price includes JE pistons, rings and the replate. Truthfully, I think this is the road I will choose, when time for the rebuild. However, I MAY just for experimentation, try and re-etch the cylinders and see what happens. Worst case is that after a few thousand miles, I'll have to spring for the reconditioned P&C's, and spend some time R&R'ing them. Best case is that they work great, and it will buy me an indefinite amount of time prior to buying new/reconditioned P&C's...maybe a year, maybe 10 years. In any case, at least the bottom end will be fresh and I won't have to worry about splitting the case...

R/
Dustin

If someone does find out how or where to recondition the alusils through an etching process (or another method, per manufacturers recommendations), I'd love to find out where, since I get emails fairly often asking about how to rebuild alusils. I would love to be able to give two options to my customers...

Charles Navarro
LN Engineering
http://www.LNengineering.com
Aircooled Precision Performance

Jack,

The burn-off at start-up is only when the resevoir is filled with extra oil. When I keep the oil at about the 50% mark there is no burn-off. I remember reading threads here about slight seeping of oil when overfilled and a quick burn-off on start-up. Again, keeping at about the 50% mark, no smoke on starts. I installed the valves per the factory manuals and the Bentley, Waynes book was not available when the work was done.

Doug,

Like usually happens, I agree with you on advice to follow,

Simon, I cleaned/polished my cylinders with a scotch brite pad wrapped arround a standard 3 arm hone. I did use oil. The finish was simular to what I saw at the bottom of the cylinder where the rings don't touch. About 30 seconds at the most and about 10-25 slow strokes up and down with the cordless drill.

This simple procedure worked for me. I've now got about 2500 miles on the rebuild and no smoke at all.
I was willing to take the risk. At that time we didn't have all this knowledge we are seeing here on the board. The info we saw from the cylinder manufacturer use of silicon paste and a felt pad is what I now believe would be the right way to go. Probably after the BFPW. Or at least a good cleaning with the same chemicals.
Anybody put theirs in the dishwasher?

This is indeed an excellent thread. I'm curious about where the guys are whose Alusil re-ring jobs failed. It's considered a crapshoot, but where are the failures? Also, JW's BFPW uses a solution that's supposed to be aluminum-friendly, so I doubt that it would have removed much metal. But it sure got them clean, and made the surface....well....not "rough," but it was different-colored and less smooth (the glaze of course had been removed). Again, cylinder taper was no more than .0015" (my motorhead friends called this wear "miniscule"), and the ring lands were also WELL within spec. I've got right at 50k miles on these new rings, and no problems whatsoever. I'm getting tired of checking oil level between oil changes. Nearly a waste of time.

If you mean, cylinders, no.
But I *did* put the cam towers in Mrs. Z's dishwasher.
The lumps on my head are almost gone now!

Anybody seen the show Mythbusters?
This would be a good case except wouldn't get the ratings like blowing something up!
If it is a myth, I wonder who started it. Somebody must have had a bad experience with re-ringing.

With all the knowledge in the audience I wanted to ask what's so special about Nikasil? What or how is it made and why is it better as we are led to believe? What are the differenences in the 2 types?
It seems like a lot of Alusil cylinders are being reconditioned replated with Nikasil what is the process? Do they etch the Alusil in the process?
I've seen some dammaged Alusil Cylinders posted most of these don't seem to to have anything to do with the material the cylinder is made of.
There are probably a lot of Nikasil cylinders with the same dammage.

It also seems like the Alusils are wearing pretty well and alot of them are measuring withing the wear limits?

Super,
I'm with you on this one. I'd love to know why...and maybe Jack is right about contacting Porsche...re-ringing Alusils is such a gamble..? Rondione offers some very compelling information on the formtaion of the casting itself and the fact the silicon particles isn't simply a "plating" but actually saturated within the aluminum structure itself (at least thats my understanding). From my VERY limited knowledge (okay, none really) it just seems logical that new particles can be re-exposed through an etching process, and the limiting factor is essentially the cylinder measurements. Perhaps all these years of folks saying it was a bad idea to re-ring Alusils really skewed the sample of folks that may have tried this process choosing instead to go with new P&C's(?)

R/
Dustin

Is this an opportunity to horde up all the orphaned Alusils and sell them for $$$$ once the myth is busted? I have seen previous threads saying that they are worth 10.00 which is a shame.

When the truth is exposed I will no longer hang my head down low with the thought of my cylinders. I will walk proud with my brethren and form the new 911 coalition ACR "Alusil Cylinder Renegades"

SCWDP, GuppeB, and Rgruppe beware! ACR is no longer walking in the shadows.

Indeed. Clean, re-etch and go. That would make Alusil cylinders nearly a "forever" cylinder....the opposite of its reputation. So, perhaps when lemmings throw their away.... When I was about four years old, I developed this irritating habit of asking "Why?" And I've never stopped.

I assume at some point they will wear beyond the ovality specifications. Wouldn't it be possible to get them bored a hair oversized exposing a fresh surface. I would think EBS does this before plating with Nikasil.
They should be able to provide a "1 over" piston and ring set.
WHY? WHY NOT?

Konish,

I believe you hit the nail on the head. There is evidence that some of the ring material transfers to the cylinder wall during the initial wear stage.

Smestas,

I've been looking into degreaser formulations, and several contain alkoxides (i.e. butoxyethanol), which can be reactive with aluminum under the right conditions. I've seen a few commercial aqueous parts washer solutions that also contain alkoxides or alkoxide polymers. It's entirely likely that a degreaser available to a home mechanic would be reactive enough to etch. If I remember correctly, one would only need to etch a micron or two to expose fresh silicon.

Aluminum, good or bad, is highly reactive. That's one reason you shouldn't get bleche-white on your rims, because it will pit them quickly. Last year I bought some stainless steel cookware with aluminum handles, and the manufacturer forbids the use of lemon scented dishwasher detergent because it will eat up the aluminum.

Scotch brite pads, if nothing else, would insure that no part of the cylinder was left uncleaned and possibly unetched. Maybe the best thing for us alusilers to do is send our jugs to JW and have them run through the BFPW.

You know now that you mention it I recall the back of the degreaser product (castrol degreaser/purple bottle) saying that prolonged exposure on aluminum parts can cause damage. So when I used it I was cautious to rinse my parts with water afterwards.

Ok guys,

Almost everyone pukes at the idea of running a grape style silicone bead hone down a cylinder (any kind) but no one says anything negative about ETCHING)!!!???

The grape style hone cannot remove any signigicant material, of any kind and is extreemly unlikely to damage any finish of any kind.

BUT ETCHING??!! Chemical etching, in an uncontrolled manner, no less, is a process that COULD ruin ANYTHING. ANy chemical that etches the cylinders is removing orders of magnitude more material than the grape style hone, and in a completely non understood manner.

Furthermore chemical etching will NOT leave the grooves NECESSARY for proper lubrication. If it works at all its a fluke, if real etching is happening, not just some slight change in appearence, which could be at an optical level, insignificant for mechanical considerations.

Its amazing to me that a practice, long accepted by racers (over 15 years), is poo pooed, but a completely unknown, unverified, and non supported by any engineers or scientists at any real company or racegroup anywhere would be considered to be possible better.

Sorry for the rant, but what can I say??

The source of the smoke is probably still the same, ie the valve guides. Maybe that the ammount of oil just overwhelms the guide seals, its possible. Not only that it is the only source for oil that burns off quickly, there isn't any other. Keep the oil at the proper level as the side effect of a little extra oil is a tendency to detonate early, which will either reduce performance (because the knock detector is retarding the timing) or engine damage because of the excess knocking ( maybe unheard, but still there).

I didn't remember seeing a response to the question about valve rubbers. Did you remember to use protection? If not damage to the valve seals is highly likely.

expert advice vs dogma
 

Jack,
Yes, I'm a very junior member to this board, but I have lurked for years, and it seems your very own statement:

"Its amazing to me that a practice, long accepted by racers (over 15 years), is poo pooed, but a completely unknown, unverified, and non supported by any engineers or scientists at any real company or racegroup anywhere would be considered to be possible better."

Is the same kind of advice ALMOST everyone states about not being able to re-ring Alusils. It also seems to me that you stand in the minority of a lot of "conventional" ideas, which I don't think is bad at all...in fact, I think its refreshing. You have to admit, there seems to be more "expert" advice suggesting this is largely a crap shoot. Actually, I kind of like your idea about the grape hone to knock the ring material out of the pores of the cylinder walls, and I'm not sure anyone suggested etching in a completely uncontrolled manner. For me it comes down to wanting to explore other possibilities while looking at this problem in a quasi logical fashion, and this discussion is really starting to move outside the box a bit. The bottom line is that I have not heard anyone, expert or otherwise give me a definitive explanation why a controlled re-etch of the cylinder is not possible making a re-ring unlikely to work.

R/
Dustin

Interesting...check this out...

http://frwilk.com/early944/cylinder.htm

R/
Dustin

snowman,

Remember that we're just talking about alusil here. Of course honing is the preferred method for most cylinders, but it is not generally accepted for alusil because it doesn't work as expected. This has been demonstrated, and is also stated by Porsche. The simple fact of the matter is that if honing worked, this thread wouldn't exist.

>Its amazing to me that a practice, long accepted by racers (over 15 >years), is poo pooed, but a completely unknown, unverified, and non >supported by any engineers or scientists at any real company or >racegroup anywhere would be considered to be possible better.

Actually, there at least 30 years worth of knowledge in the scientific and engineering literature on silicon-aluminum alloys. Like I said before, I'd be happy to provide references for those with access to a university library. Porsche didn't invent this stuff, they just employed it.

Your assertion about oil in the grooves is entirely correct. It's also true for these materials. But rather than linear grooves that honing would produce, these materials have more random voids left between the silicon particles from the etching. This is also in the engineering literature.

As a matter of reference, our understanding of etching from both chemical and electrochemical perspectives is very well defined. The semiconductor industry has developed routine methods for pure chemical etching submicron layers off aluminum films with exquisite control. And if we etch electrochemically, that is by applying and controlling a current that ionizes and removes metal atoms from the materials' surface, we can control the etching process right down to deciding which metals are removed and which are left behind.

But, have you ever looked at a cylinder wall with an electron microscope or a profilometer before and after honing? Of course not. This is not science. You don't know how deep the grooves are that are left behind by any hone, grape or otherwise, and I promise that they're all different anyway. What works in our favor is that the margin of acceptable parameters is huge. A surendipidous etching may work just fine. And for us alusilers, anything that works is better than where we are now.

One last point: the etching that is achieved by a degreaser or cleaner is going to orders of magnitude less aggressive than the etching achieved by acid, or bleche-white, or even tomato sauce. This is because degreasers are not acidic, they are generally basic. Furthermore certain ingredients like alkoxy alcohols are slightly reactive with the aluminum. And I made the offer before that if anyone wants to donate an old alusil jug for some etching experiments, I'd be happy to carry them out. I have access to all the equipment necessary to characterize the cylinder surface before and after treatment.

Konish, I could not read the bottom of the page or scroll down where it was leading to the good part about what Porsche recommends. with the Sunnen Machine.
Jack, your idea is very simple and you say it's proven. It could be done by anyone sucessfully. I hope my scotch brite polish will last. If not I'll move on.
There's more than one way to skin a cat.
I'm still waiting to see if KS reply's to my e-mail.
Did anyone try porsche?

William,
The last sentence was the last of the web page, and I'm not sure if there was supposed to be anymore info, but I agree in that it is open-ended suggesting there was more to follow. However, elsewhere on the page, there was a link to the same page that Simon provided earlier, which I just assumed was the procedure to which the artilce refers.

R/
Dustin

I understand a lot about etching as I used to manufacure thin film mircrowave circuits, and design semiconductor ics that required even more precise etching and special processes. But what has been discribed so far is far from any kind of controlled process, and certainly no coupons have been mentioned, ie the first step in controlling this type of process.

What seems to fly over the heads of all these discussions is that the silicone ball type of hone is NOT what might be considered a conventional honing process in that it does things a little differen't, in very important ways than what honing stones do. Again I would refer you to the manufacturer for this information. I think you may find that the process with the Sunnin hone, using silicone paste may be exactly the same as using the siilcone balls, except that you only need a drill to use it, not a $30,000 Sunnin honing machine.

Jack,
I read your answer to a previous questions about your actual experience using flex hones to recondition alusil cylinders, and it does sound like a reasonable process. I read as much as I could about the flex hone, and plateau honing over the past few days. Just out of curiosity, how many sets of Alusils cylinders for the 911 have you done this way, and were the results always the same...ie no smoke, good compression, etc. When was the last time you did this, and how many miles are on the last set (if info is available)? I'd really like to explore this option more, but I have to admit without more data, I remain a bit skeptical...but no more so than anything else we have discussed. Again it might be worth just running an experiment...worst case the P&C's have to be replaced, which is essentially square one anyway. Not trying to be a wise-ass, but if the thing works as well as you say, and it's as simple as running the hone in and out of the cylinder for a few passes, I wonder why the process isn't even being discussed as a possible alternative in any of the authoritative literature on rebuilding 911 engines? In every case, I've basically read that Alusils are disposable....? Again, take that last statement however you want, but it isn't meant as an attack or disrespect. Essentially, I think the real value of this thread is to reveal real data that PROVES Alusils can't be reconditioned reliably. For the most part, I rely on expert advice from guys who have great reps in this field, but as I seem to get their "word" second hand, its hard for me to draw any substantial conclusions on this matter.
R/
Dustin

OK snowman I'll take the bait. You probably posted the manufacturer's info before, but could you post it again along with some references to the hone's use? Also, are there any references that you are aware of for using this hone with the other alusil engines (vega, bmw)?

Believe me, I hope you are right. Buyign a specialized hone is far cheaper than buying new cylinders.

The following sites have very interesting info on cylinder honing. Free literature is offered that details how Flex hones work and why they are the way to go for final honing or reuse of cylinders that can be honed.

http://www.brushresearch.com/Index....chnicalBooklets
http://www.brushresearch.com/Index....e.FlexHoneTools

I have only a couple sets of Alusils. In addition I have done 7 or 8 other engines.
All with same result, rings seating within 5 minutes of startup, No to nil oil consuption, more power.

The auto tech professor who put me on to these has seen the results of several hundred engines, of all types, including many Alsuils. Always good, always worth doing. He has been using them since they came out, and typically tries every new innovation coming out of the woodwork.

I have read all the available literature, including the newsletters for full time engine rebuilders, and these things are the way to go. UNless you have a sunning hone and can use silicone paste, for just a few cents more, vs buying a $60 ball hone.

Sorry for jumping in here late but let me just make a couple of observations. First I'd like to say this is by far the best thread I've seen, exactly what makes the web such a cool thing...

On topic, it seems like the bad rap that Alusils got was earned in the early days well before it was understood (like it is now???:) how to re-finish them, and Superman, well before the advent of the silicone flex-hones came out. I can imagine DIYers in the 60s and 70s using traditional honing equipment and cutting oil on them and having catastrophic results.

FYI I have found a doc that was scanned re this process for 944, 928 etc engines and will post or link once I finish downloading it. At first glance it also talks about using the c10 and finishing with the silicon and felts pads.

It seems to me all we need to do is find a source for the silicon paste, felt is easy...

In the past, Alusils had a bad rap because they'd wear out of spec faster than Nikasils. The idea that they can not be re-ringed is a fairly new proposal by my memory. Both sets of Alusils I've had were far to worn to reuse anyway.

I agree, this is one of the best threads on this board in a long time. The best part it the discussion has focused on the facts, rather than degrading into personal attacks. Thanks everyone.

JP

I have just had my alusils done by a local shop that says he has done hundreds of these on aircraft, Porsche, Mercedes, and Vegas.

They were 'honed' with a felt pad and an abrasive paste for about 30 seconds. They now look clean and shiny but close inspection shows a very light cross-hatch is present.

I don't think I can upload a hi-res picture here, but this what I they look like.

http://forums.pelicanparts.com/uploa...1072105563.jpg

PBH,
Wow, they sur elook good. Funny, I was just looking at aircraft engine rebuild sites about the very thing. Some of my friends in the squadron have private planes, and eventually they all have to submit to an overhaul. I would suspect that quite a few private aircraft use Alusil cylinders...most being made in the early to mid 70's, and I'm almost certain a percentage of them have been rebuilt by reconditioning the cylinders. Interesting post!

R/
Dustin

I wouldn't pass the aircraft r&r test, I am at the low end of bore tolerance, but I don't expect to drive this car a lot, only the occassional weekend outing in the summer.

Hmmm...seesm the BMW guys needed to swtich FROM Nikasil to Alusil in an attempt to stop the high sulphur content US fuels from destroying their Nikasil coatings. Here is the link:

http://www.koalamotorsport.com/tech/misc/v8shortblock.htm

R/
Dustin

PBH, could you ask the shop what paste they use ?? Thanks for the pic too, its a good example of what was said earlier about the difference between a traditional cross hatch on cast iron (non-porsche) cylinder walls and the correct finish on the alusil.

"Hmmm...seesm the BMW guys needed to swtich FROM Nikasil to Alusil in an attempt to stop the high sulphur content US fuels from destroying their Nikasil coatings. "

Does anyone know or have a guess as to why the BMW cylinders have this issue and the Porsche Niks don't? Is it the higher operating temps ??
(just curious)

There should be NO difference between any cylinder of any material for the cross hatch pattern.

The angle of the cross hatch is important, though not especially critical. If the cross hatch pattern is not there it is a very very BIG problem as the rings will not be lubricated. Its these small grooves that hold the lubrication for the rings. With the correct ammount of grooves and approximate angle the grooves provide oil for the rings to float on.

If the grooves are worn out, ie gone, the cylinder walls and rings will wear rapidly. The grooves must ALWAYS be t here. A properly running engine will not have ring ridges, will have cross hatches, even at 100,000 plus miles (because the oil is lubricting and preventing wear).

I read the link and found it interesting. Funny thing is all the Porsches where this problem hasn't shown up. Specially considering the high mileage SC's with Nickasils you see on this board that haven't exhibited this problem. Maybe BMW hasn't really discovered the root of the problem but have come up with an alternate fix.

Note the reference in the article to engine temperatures (changed EPROM and t-stat). Maybe it's a good thing to be air-cooled, with higher operating temps. Porsche has put plenty of Nikasil cyls. in engines, without any problems.

Sounds logical except that the high mileage alusils I have seen have no ring ridges and no cross hatches left. Does anyone have any evidence contradicting this?

My guess would be that the alusil surface can hold sufficient lubrication without a crosshatch.

Snowman, there is a difference between alusils and others. While your statement hold true for almost every other engine, alusils are not honed at the factory. There is no original cross hatch pattern. That doesn't mean that there aren't microscopic crevices to hold oil, however. The crevices are random interstices between silicon particles.

FWIW, here are some good references from the engineering journal "Wear" to articles concerning the wear properties of silicon-aluminum alloys similar to our alusils. Also see the IEEE journals and "Surface & Coatings technology". One of the interesting properties of alusil is that the ring material transfers to the cylinder wall during the initial break-in phase. This causes the cylinder wall to adopt a hardness similar to the ring, allowing for maximum durability. Knocking some of that material off could be part of the key to a successful reringing.

One of these days I'll post a list of references that I've found.

Interesting info. If the initial transfer of ring material to the cylinder walls is what keeps these things alive, then there should never be any cylinder wear, just piston ring wear and piston land wear. So unless something has gone wrong, one should be able to save these cylinders for several sets of rings. Or is there more stuff going on that allows cylinder wear as well?

In any case the removal of the original ring deposits would make a lot of sense. Having some cross hatch shouldn't hurt either. If silicone paste is used vs silicone flex hones, using the same grit, is there really any difference?

Anyone talked to a Porsche engineer yet?

You know snowman, there may be something to your honing ideas. Smestas posted this a few days ago:

http://www.msi-motor-service.com/download/broschueren/alu_en.pdf

I've read it before, and I always thought that they were referring to a cast iron liner that is fitted into an alusil block. Upon reading again, I see that they are fitting an alusil liner into an alusil block, to end up with something more like the lokasil. But then it's honed with the sunnen machine. My apologies to smestas!

Also, if you go to the Kolbenschmidt web site and read some of their literature, they emphasize that the new cayenne blocks are not etched, but that the silicon particles are "mechanically exposed". I suppose they did this because there is no way to etch only the cylinder (etching is done in a bath), and etching an entire engine block would have unintended consequences. But obviously honing can be done with the proper equipment. I know that somebody has contacted porsche to inquire about honing, but has anybody contacted KS? Or Sunnen?

It's also worth wondering this: Is the current alusil material the same as the older alusil material?

I sent KS an email yesterday about it and haven't heard back from them. I've also been trying to find out exactly what kind of silicone paste is ised and where to get it but nothing yet.