Recondition Alusils?

[Steam Driver]

I know that the conventional wisdom about Alusil P/C's is that they generally cannot be reused, so how is it that the Ollie's Machine price list lists a "Hone Alusil (Recondition)? Has anyone had any experience with this?

[RedCoupe]

Hope someone with experience in this area gives you a response. In the meantime, I would call Ollie's. I can't remember the name of the two owners, but they are both very experienced Porsche machinists and would definitely chat about this service with you.

[Eagledriver]

I know what the conventional wisdom is, but I've reused Alusils with success. If you are rebulding an Alusil engine, I'd measure the ring gaps, ring land clearance, and piston to cylinder clearance (at the skirt using feeler blades). There are specs for all these published in the various books. Some basic numbers are: Piston to cylinder clearance-less than .004 inches, Ring land clearance-less than .004 inches. Piston ring gaps I don't recall, but I think the limit is around .030 inches.

I think you'll find that your old rings have better specs than any new ones you can buy. If all that checks out, just reuse what you have. I just do a light hone with scotch brite and run the cylinders through the dishwasher (wife not home for this step).

I haven't seen a case where the pistons and cylinders were in good shape but the rings were worn out. If you find the rings worn out then maybe Ollies hone is a good idea. You have to decide if you can live with taking the engine apart again if it doesn't work.

-Andy

[The Watson]

I believe Ollies told me they send them to EBS who will just swap them out for one that have been recoated.

[peppy]

I use them in my rebuild. I sent my cylinders to EBS they had them bored and coated, then sent them back with 3.4 JE pistons.

They have worked for me, but I am using more oil than before the rebuild. I was going 1500 miles before adding a quart, now I go 800 to 900 miles before adding oil. I was also using Castrol before and now use Kendal, so not a fair comparison.

[Walt Fricke]

US Chrome and some other shops can turn Alusil cylinders into Nikasil cylinders. But you can't use your Alusil pistions in a Nikasil cylinder.

So, if either your pistons or your cylinders, or both, are out of spec, you are kind of stuck unless you are willing to acquire good used Nikasil pistons, or want to try aftermarket pistons. And have the cylinders done.

[DSPTurtle]

Walt, I just spoke to US Chrome about using KS pistons in their replated cylinders. They assured me, very strenuously, that the KS pistons and OEM goezte rings would be perfectly happy in their NICOM replate. Do you have specific experience with this not working? I even asked to talk to a second person and they had the exact same explanation. Thanks in advance for your insight.

[jjeffries]

Sir, I'd suggest you contact Tom Butler (tom1394racing), who runs RennShop in Portland, CT. He's something of a guru on Alusils, and saving them. Very helpful gentleman. John in CT.

[kenikh]

There's a 20 kajillion page thread on this topic. Read it.

[DSPTurtle]

There's a 20 kajillion page thread on this topic. Read it.

If you're talking about the 31 page thread on re ringing alusils, I've read that many times. It doesn't talk about detrimental effects of the iron coated piston in NiCom. If there is another thread, please kindly post a link because I can't find it.

[Steam Driver]

Thanks for all of the useful information and leads on this issue. Lots of things to follow up on!

Who/what does "EBS" stand for?

[DSPTurtle]

Engine Builder Supply.
Lots of Porsche engine rebuild stuff!

[Walt Fricke]

I'm basing my beliefs on what I have read from numerous sources. I'd have to check, but Bruce Anderson's book may touch on this, as may Wayne's 911 Engine Rebuilding book.

I'd be dubious about rings for Alusil working with Nikasil bores, and vice versa. But that's not based on personal experiment, or even deep knowledge of what goes on between rings and cylinders.

Aluminum skirts (standard pistons for Nikasil) work just fine with Nikasil. Obviously they don't with Alusil, or Porsche (and GM) would not have had to apply some kind of iron coating (or maybe it is a plating) to their Alusil pistons.

Nikasil is plated onto aluminum cylinders. Alusil, as I understand it, is a silicon which is part of the cylinder casting, and the face is then etched or something to expose more of the silicon and less of the aluminum. Something like that.

My assumption is that that iron coating is not compatible with Nikasil. If it turns out to be, great - I have a perfectly good set of SC Alusil pistons in my "can't bear to throw away any of these parts" bin.

What is needed here is information from someone like Chris Seven, or Jake Raby or Charles Navarro. US Chrome is great at doing the Nikasil plating and machining to bring old cylinders, be they Nikasil or Alusil, back to life for use with uncoated pistons. I wouldn't discount what they say out of hand about this, but I'd need more of an explanation. Including why everyone who seemed to know something said you can't do it.

[bh912e]

I have re ringed alusils. Soap and water with dish washing sponge for the cylinders. Measure cylinder bores along with taper measurement. Check pistons for ferrocoat, check for scoring. Gap rings! Put back together....

[Walt Fricke]

BH - the issue here isn't re-ringing Alusils, or otherwise reusing them. It is the assertion that you can run Alusil coated pistons with Nikasil cylinder bores.

One possibility here might be if you coated the pistons, so the ferrocoat didn't come into contact with the Nikasil? Conventional wisdom, which is being questioned here, says that the ferrocoating is incompatible with Nikasil.

[SCadaddle]

Originally Posted by DSPTurtle

Walt, I just spoke to US Chrome about using KS pistons in their replated cylinders. They assured me, very strenuously, that the KS pistons and OEM goezte rings would be perfectly happy in their NICOM replate. Do you have specific experience with this not working? I even asked to talk to a second person and they had the exact same explanation. Thanks in advance for your insight.

Went through this last year. Search this forum with my username. At that time I was assured by a well known engine builder out in California initials H.S. that the original KS pistons would run fine in the (EBS) plated Alusil cylinders. Don at EBS assured me of the same, they plated my cylinders and provided the set of rings.

So hindsight is 20-20. What did I learn?

1) You could probably have someone use the Sunnen hone and method on your cylinders. However, you'd better find a source for the correct chrome rings @ more than $600 for the set. Best bet would be some guys named something like Hans and Frans somewhere in Germany, because the "available" Goetz rings just aren't going to work in an Alusil cylinder. Regardless, re-ringing an alusil cylinder is a crap shoot. It might smoke, it might not.

2) In order to use the "available" $150+/- set of rings with the newly plated Alusil cylinders and your original alusil pistons you're going to spend, by the time you add up the plating,machine work, rings and shipping, about $1,000.

That being said, option 2 above might seem the way to go. However, you've now got an engine that the masses "in the know" claim just absolutely will not work---and you've got to think about that down the line come resale time.

As for my 82 SC engine, I've passed through about 5,200 miles so far with the usual smoke on cold start up but no smoke once it is running. Oil consumption has been less than 1 quart in about 1700 miles.

[arbita1]

I had looked into this a few years ago and this is the email Ollie's sent me on it.

Hi Matt,
We've been using Sunnen equipment for many years now that has a process to handle Alusil honing. Please give us a call and we can discuss the process with you - ask for George.
Ike

Like SCadaddle said the problem with this solution is finding the correct chrome rings which are much more expensive than the typical set.

[Walt Fricke]

Honing (followed by acid etching?) sounds like it could work to return the Alusil cylinder surface to what it was when new. Maybe. However, this will open up the bore, and you will have more clearance with your original pistons. Perhaps this is just a little, and doesn't matter.

But in that case, why would you hone?

If it is because of uneven bore wear, I'd think the oversize would be more than was good for the stock piston. But maybe I am wrong - when the early 80mm iron cylinders got worn, they were bored out to 81mm. SCCA specifically allowed this as still being eligible for the 80mm class. Did new pistons, wider, pistons go with that? If not, then I guess you can stand quite a bit of more clearance without causing rings or ring lands to break.

I did some quick Google searching under Alusil, and found quite a bit of useful information, including useful discussions around the fact Alusil is an alloy of aluminum, and not a plating like Nikasil. And how the silica component of the alloy is worked after casting so the hard parts do their job without tearing up the rings or piston skirts.

I'd want to quiz US Chrome, and any machine shop with a good Sunnen hone machine, about those aspects of the deal.

[RedCoupe]

Boring the old cast iron cylinders 1mm oversize is about .0394 inches, or just a nat's hair less than the old 40 thousands overbore done on so many American V8's. Acceptable piston to bore clearance was probably in the order of .1 mm, so oversize pistons were definitely in order.