I would have thought everything Alusil was trashed by now. We knew back in the 80's that Alusil was junk and easily recognised as that. Nikasil is still the recognised state of the art.

Alusil is still used by most manufacturers today when a steel liner isn't used.

A modern engine, with proper honing and materials, will not show wear in the cylinders. The rings are meant to wear, the cylinders have grooves that hold oil that lubes them. The cylinders do not wear because of the oil film does its job. Consequently you will not see a ridge at the top of a modern cylinder, nor any apparent wear. You can measure the cylinders to confirm this.

The rings and pistons will wear. The seating surface for the rings is the first to wear out. Thats the flat, side, surface of the ring grove. The rings may actually outlive the piston. When this happens, you need new pistons, plus rings.

The rings need to mate to the cylinder. To do so requires a fresh honed surface. To achieve this surface all that is needed is a quick honing job. The honing stones must be hard enough to cut the very hard surface of the cylinder. Consequently a silicone stone or silicone slurry is required (or a diamond hone), ie anything harder than the cylinder material. The hone only has to refresh the surface, not enlarge the cylinder, so a very fine grit is used. Thats all there is to it. Of course a chemical method can achieve the same result, if a suitable method can be found. There is no documented chemical honing method that I know of, but its possible.

Thats my latest on my assessment of whats going on with these cylinders.

Jack,
Did you ever do the comparison testing of the "grape hone" vs. the lapping/AN-30 Sunnen felt pad/turtle was cloth test that I believe "Randidone???" did?
I was wondering because I am at that stage of the rebuild and was thinking of what grit to use (I thought in the earlier part of this thread you used 180). I was looking at them on the site you spoke of.


Thanks

No I have not done a comparison test. I was hoping that it would be done. No one ever sent me a sample cylinder like was promised. I have given up on it at this point. As far as a grit, anything above 180 should be ok, but above 220 would be my first choice. More than 400 is probably to fine as you need some depth in the oil groves the hone makes. The idea is to make an oil film surface that the rings can ride on and not cause wear to the cylinders. The hone makes the groves that hold the oil.

Note this a "final" step in honing, one that does not remove significant material, it just conditions the surface of the cylinder.

Thanks Jack! I am in the process of repairing some broken Dilivar head studs and I have the Alusil cylinders awaiting something to be done with them. Was just wanting your advise.

What happened to the other guys that were really involved with this thread? I got interesting when you were to get a cylinder and do the comparison and then nothing! They must have gotten burnt out!

What is your opinion on the scotchbrite with the Sunnen AN-30 compound? My engine only had around 96K on it and my Alusils look like they are in very good condition.
Thanks

I used the red scotchbright pads on mine with good result. Don't know what grit that is. Just tywrap the pads to the hone stones. I'm glad Alusils have such a bad rep. It's saving me a ton on my race engines.

-Andy

Rondinone measured a worn cylinder, I had the Sunnen man hone it and I mailed it back.

He says he will get around to measuring it again, to see the difference and to compare to the 'ideal' surface finish.

I am hoping it will get done soon. We're 90% done, we just need to take the final step and we'll know if this process really works.

Looking forward to the final outcome!

My opinion of the Sunnen compound is that it is exactly the same as the grape hone. Silicone paste or silicone on a ball. Both do exactly the same thing to the cylinder, they put some new scratches in it and remove any minor imperfections. It really isn't rocket science, its just plain obvious. Scotch brite is just something to hold the silicone paste, just like the glue holds the silicone in the balls.

Scotch brite pads by themselves may work by simply cleaning up the old cylinders, ie removing the dirt from them. It may be that no more is required to revive the cylinders.

Personally I suspect that there is enough microscopic wear to justify introducing new groves in the cylinder walls, ie the cross hatch pattern. If enough oil is not retained in the cylinder walls they will wear out, consequently a few passes with silicone paste or silicone balls is needed to refresh the surface.

Cylinders
 

My mechanic friend rerings Alusil all the time....13 seconds of the ball hone and its good. He hasnt seen a failure yet..and he is a factory trained guy.

Get the right rings....thats important.

Just remember this is a forum of where you will see the worst cases come out. They may not be the most desired but it doesnt mean they are junk either.

That is what I picked up from this forum. If you are not going to build a race engine then you should not have anything to worry about either. I was prepared to rering my alusils and disassebled the motor and found out I had Niki's... So I personnally dont have any compressions numbers to give to you.

I am soooo *pissed off* right now. Snowman I have 6 Alusils that I will send you, they are not any good to run on an engine, but good for tests. If you want them send me a pm with your address and I will send them out on Friday.
Now, my story. I have a dreaded 2.7 I am rebuilding. I have sent the case out and done all the mods. I was told by everyone that the 2.7 used Nikasil on the Mahle cylinders. Well, I am too stupid to know the difference, or care. I am thinking I am not going to run into any of the rare Mahle Alusils. Well, my cylinders were in bad shape. In order to keep the costs down on my rebuild I bought a used set, in spec Mahles off of ebay. I get them, they are the same as the ones on my car. Great, I measure them up and I am getting the prepped and ready to go. In the process I found a very small defect in the chrome in one. Crap, I need a single. I find one from a forum member and he assures me it is nikasil. So I buy it. So, I buy my rings and I am cleaning and measing the single cylinder I bought. Funny thing is that the chrome has different apperance. Hmm, it is shiny, mine are all dull.....So I go look up what the chrome is. I am thinking the single is Alusil........ Hell no, a magnet only sticks to the single I bought. So, I have not one, but two sets of Mahle brand, Alusil plated 2.7 cylinders, and a set of Goetze rings that are not correct for the cylinders even if I do use them..............
I preped the cylinders with red scotchbrite pads. Then when I went to prep the Nikasil cylinder there is big difference, the Alusil will scuff a lot easier than the Nikasil. Anyway I have a nice set of 5 Alusil and one Niksil cylinders that are in spec..... grrrrrr. I know where one more Alusil cylinder is that I can get to make a set of Alusils. But if I decide to use them I take it that I need to plate the pistons. They are marked Mahle, but are for Alusil cylinders and are a slightly different shape than the pistons that are run in Mahle nikasils.
So, I guess I am asking if I have screwed up by prepping them with red scothbrite, and where and what coating do I need on the pistons to make them useable if I reuse them?
Snowman, send me your address if you want a set of them, on me.
Ray

The joy of the 2.7 rebuild is long behind me, but I feel your pain.

Back to eBay? maybe you should call the engine rebuild guy.....I'll think it shortly....

Henry Schmidt - he has posted here before saying he'll sell used alusils cheap, no guarantee though.

Let me get this right
 

You have 5 cylinders that are alusil and one nikie?

I would keep them. They are not a bad product, I think that education is the key to why they are so "dreaded" much like the 2.7 motor....which I think is a good reliable motor, just lacking foresight during the design/production phase due to inadequete research in heat management.

I had the same worries but, it really sounds like you have a parts management problem more than anything else.

But what I have been wondering is can the alusil be bored out? Since the cylinder itself is alusil all the way thru, which differs from the nickies because they are plated it seems that you could bore it out and make a 2.8 liter motor or greater?

chris

Yes, that is correct, 5 Alusils, and one Nikasil, but I can scare up one more Alusil. So I can get a matched set of them. I am not opposed to using them, but I guess the pistons are plated and I am not sure what plating to get or where. I bought the nikasil clinder because I got one bad one from the ebay batch, the top was beat up from a loose stud, imagine that. I am also not sure where to get the rings for them. Pelican only shows one ring for the 76 2.7.

Correction, Pelican does show the LS rings for the 2.7, just have to look. :) If I run the original pistons and new rings do I need them coated? They don't appear coated, or it is long gone.

Ray,

If you have pistons that belong in Alusil cylinders they will have a ferrous coating on them. It looks like a pale goldish rust layer (it almost looks like anodizing). It will probably be worn off somewhat on the skirts. If you can't see an area that looks different then either the coating is all gone (doubtful) or the coating is still good and on the entire surface. The sets I've used have had about half the coating on the skirt worn off. They seem to work fine that way. My last set I had the skirts coated by Swain with PC9. Beware that the PC9 coating will make your pistons tighter in the bore.

-Andy

Darn, I hate to say it, but you are in between a rock and a hard place. Without a set of known pistons and cylinders you have made the uncertainty high enough to make the recommendation of a new set of pistons and cylinders the best recommendation.

If you have a complete set of cylinders and pistons that are KNOWN to have been a set, you are in good shape, you have a chance. Anything else raised the bar high enough that you should only try if your time and the parts are almost free. Just to many unknowns. Thats for any type of cylinder. At this point I would hesitate in putting more money after bad money, sorry.

I have found that once you have gone this far and found that you are screwed, you should regroup and go the high price way as the "low price way" is now closed to you. Thats unless you want to be screwed twice, or even three times. Its just the way it goes.

Yes you can stick to it and maybe come out ahead, but my 35 plus years says that you will, most likely, not.

Well gentlemen ... I'll let you know how it all comes out. I have an '82 3.0L that the PO must have done a top end on. Unfortunately, he left the pin out of the cam gear on the 4/5/6 side and eventually the cam gear moved. The exhaust valves all hit the pistons until #5 gave up ... broke the head off and punched a very large hole in the piston with some "minor" head damage (not really that bad).

So, I have acquired a set of (hopefully as reported by seller) "in spec" matched Alusil P&Cs. I'm gonna re-ring them. I'm gonna use the ball hone on the cylinders. We'll see if it was a waste of money or I come out good.

Unfortunately, I am in uncharted territory here as it's going in a 914 to replace a 2.4 so don't hate me to much.

OK, I finally got around to doing this. I know, just two years. Sorry.

Actually, I changed jobs (very good for me) and things got hectic, the cylinder sat on a shelf in my garage. Seems like every time I remembered to do it something would come up and it got put off again. I found it recently while preparing to move (changed jobs again), so before I left my old position I put the cylinder on the electron microscope and had a look. Sorry for the delay but sometimes life gets in the way.

Here's what I did. I broke the cylinder up (carefully), and took a 1 inch piece from the skirt (but within the piston travel, so that wear would be present) for testing. The piece was cleaned with solvent, and into the SEM it went. All the images were taken at 30kV. The magnification is shown in each image (400-8000) as is a scale bar. The notation is for the entire length (all the marks together).

I'm not sure of the actual treatment that was applied to this cylinder, but the results were not exactly the same as what I was able to produce in my garage. You can look back in the thread to see what I could do. This cylinder showed some signs of galling and broken silicon inclusions (most were not broken) and extensive pitting (likely due to wear, not the treatment). Although there was some evidence of silicon destruction, there were plenty of intact silicon inclusions. The extensive pitting made a conclusive determination impossible because as you see below, there is not a smooth surface. However my feeling is that this treatment is OK, since there are many clearly visible silicon inclusions protruding from the surface. There was a degree of aluminum smearing (not carving like the gall, but more of a smear) that I cannot explain and am not real comfortable with, since the aluminum must be cut back for this material to work correctly as a cylinder wall. As you look through the pics below, note that most of the small round objects present are aluminum debris or small silicon bits sticking up from the surface. Things that are perfectly round (you'll see a few) are drops of leftover oil that was not removed. I did not make a surface profile measurement (to measure how far out the inclusions protrude) because I no longer had access to that instrument. Let's go through the images:

This one shows a large galled aluminum piece in the center, and two larger intact Si inclusions that are circled. While galling is very bad, overall this area is good, as we see evidence of cleaned Si protruding from the surface so that the ring has something to ride on. So we're clear, the features are identified by measuring X-ray fluorescence from the surface, not by guessing. This area is smoother than most of the rest.
http://forums.pelicanparts.com/uploa...1229912942.jpg


Zoom of galling:
http://forums.pelicanparts.com/uploa...1229909981.jpg


Below is an image of a badly shattered Si inclusion, on the very edge of the piece of cylinder (the cylinder must by broken up into smaller pieces to fit the microscope). This is just for illustration. Remember that the point is to wear back the soft aluminum to expose silicon particles.
http://forums.pelicanparts.com/uploa...1229910400.jpg


Below is an image of a few scratches that were in the cylinder wall. Once again, this could be a result of the treatment or the prior usage. However if it was the prior usage then these should have been removed by the polishing treatment. The scale bar in the lower right is 20 micrometers, so each division is 2 microns. These scratches are around 2-3 microns across and should have been removed by a treatment process that's intended to remove 10 microns of aluminum. Some of the polygons (e.g. center top) are larger intact silicon inclusions.
http://forums.pelicanparts.com/uploa...1229910577.jpg


This image shows a few things that look good. There are several inclusions (the large kidney-shaped island on the left, some smaller polygon shapes on the right) that are intact and appear raised over the surface of the aluminum. The raised area on the lower right is also silicon.
http://forums.pelicanparts.com/uploa...1229910929.jpg


With the exception of the occasional galling, scratches and broken silicon, this cylinder looks ok. There's quite a bit of pitting but that's probably age:
http://forums.pelicanparts.com/uploa...1229911488.jpg


Obviously, I'm not going to vouch for the performance of this approach, but it does not appear that this treatment ruined the cylinder. However, it does not look nearly as good as what I produced in my garage. I am concerned about the galling, since there is no mechanism for galling with the Sunnen polishing method (if a stone hone is used, there will definately be galling), but it's possible that there was some debris on the polishing pads that caused it. Likewise for the scratches.

Hope this helps!