Sort of hard to argue with this, but someone will probably try...

A Picture is worth a 1000 words !!!!
 

http://forums.pelicanparts.com/uploa...1085762194.jpg http://forums.pelicanparts.com/uploa...1085762209.jpg
http://forums.pelicanparts.com/uploa...1085764857.jpg

Wow Henry, thanks for going to all that effort to further the knowledge of the community.

What method would you use if you were re-using the "unmolested" cylinders?

It would be interesting to know what RA the "scotchbrite method" results in, although it might be hard to create consistent results due to differences in applied pressure.

Thanks!

This is good stuff, guys. I think this is just what the board is best used for, and as someone who is in the middle of a re-build (with used Nikasil cyls. of undetermined mileage) it is defineitely a big help to me. If I do go the Scotch-Brite route, what is the procedure? Do it by hand with soap and water and elbow grease or is there a more elaborate method?
Also, will any old Scotch-Brite pad do?

Henry?

One more trip to the Profilometer
 

You asked so here goes.
First we cleaned the cylinder with Red Hot, a spray degreaser, rinsed it with water and dried it with air.
Measure it for to insure some semblance of roundness and just for grins check for taper. Most of the time they are .001 or .002 out of round. Remarkably after 104,000 miles this one is only .0007 out.
Well within my usable range. The taper as expected in a Nicasil cylinder is almost nonexistent.
Remember that 100 mm C2 ,89 and later 3.6 engine have tapered cylinders. This taper is designed to reduce piston slap on these very short skirt pistons.
After measuring the cylinder, we used a medium grit 3M Scotchbrite pad ( red ). My abrasives guy could not give me a grit but says medium or 7447 Red is his most popular hand pad for cylinder prep. It's hard to say how much work to put into this process but I worked in a spiral action from the top to the bottom until it all looked fresh. Now there are still lines created from where the rings stopped and how bad these lines are I guess will determine if you want to use the cylinder or not. In our test case you could see the lines but I couldn't feel or measure them. It's a judgment call and I'm using it. Next back to Costa Mesa R&D. John's a nice guy to donate his time to this endeavor. We rechecked the RA # of our test cylinder and much to my surprise we got a very usable 3.7. Remember it started at 3.0. I would not have guessed at that result. It is my guess that the change is from the removal of oil residue (glaze) from the cross hatch marks that made the difference.
Well there you go. It looks like we all learned something.
Good luck with your own projects.http://forums.pelicanparts.com/uploa...1085784250.jpg http://forums.pelicanparts.com/uploa...1085784268.jpg http://forums.pelicanparts.com/uploa...1085784279.jpg http://forums.pelicanparts.com/uploa...1085784292.jpg

This is a neat tool for doing this type of measurement:

http://www.pelicanparts.com/catalog/shopcart/TOOL/POR_TOOL_CAT443_pg13.htm

-Wayne

Henry,
Thanks for taking the time to post the excellent info and images.
Cuts through a lot of conjecture and plain ol' BS.

Thanks Henry!
-Chris

RUTLAND TOOLS 800-298-4787
 

Try rutland Tools or possibly Ebay?
http://forums.pelicanparts.com/uploa...1085855679.jpg http://forums.pelicanparts.com/uploa...1085855694.jpg

Henry, thanks for all the info.

Cheers, Jeff

Hi:

This has been a great thread and I'd just jump in here and affirm what Henry has said.

When we must touch a Nikasil bore, its done exclusively with diamond hones and we have a "torque plate" assembly that mimics the loading when the cylinders are installed into the case and torqued up.

I've not owned nor touched a flex-hone in 25+ years,....:)

Great info. I'm planning on re-ringing my Nickasils in a few days. My question to Henry is, if cleaning with ScotchBrite yielded an RA of 3.7, and Mahle's suggested range is 4.2 to 6.0. Is this good enough to ensure proper seating of the rings?

When reusing Ps & Cs, you always run the risk that the rings won't seat. It has been my experience that if your cylinders fit all the requirements, roundness, no pitting, no scuffing, very little taper, that using Scotchbite is your best chance at having the rings seat. If you can fine someone with a diamond hone that can achieve 4.2-6.0 RA, go for it. As of yet, I have not found that person.

Wow Henry, thanks so much again! Your willingness to go do the scotchbrite test will probably help many people in the community! thanks!

you say "much to your surprise" ... did you expect the Ra to stay nearer the original 3.0? Just curious.

Thanks!

I had no idea that cylinder graze would effect RA values that much.
I am confident that the Scotchbrite did not cut the Nikasil so I have to assume that we just removed the glaze.

Sounds like a light scuff with the ScotchBrite will remove the glaze. If one went too aggressively with ScotchBrite could it effectively lower the RA further?

I guess I'm wondering how much scrubbing to do and assuming I need to be careful and not overdo it.

c

Scotchbrite is a mild abrasive so it will remove material but mostly debris since I would bet that its abrasive is softer than nickel and carbide.

I am fortunate enough to now be working for one of the best automotive machine shops in the southeast that posses a Rottler diamond boring and honing machine. A set of 550 grit diamond stones and a pass of the carbon brushes can produce RA values between 6 and 8. That will be good enough to produce a new and improved hole in my nikasil cylinders. How do you think Mahle did it?

Once I get done building the preload jig for my cylinders my short block will be all ready to go back together. If all goes well my shop will then be offering reconditioning for reusable nikasil cylinders. If I can find a qualified plater in the region we may go as far and boring and relining.

As I often say at the shop, its not rocket science. :cool:

Henry,
"If you can fine someone with a diamond hone that can achieve 4.2-6.0 RA, go for it. As of yet, I have not found that person." I was told that Motorworks of San Diego can do this and does. I think it was Tom or John at Extreme Motorsports that told me. He also said that they have a special set up to do Alusil.

Thanks for going the extra miles!

I believe that you will have a hard time overdoing it. The Scotchbrite (7447) will remove the graze but not much more. Remember that we used degreaser then hot soap and water. I worked in a spiral motion and was very pleased with the results.
We have found one problem with diamond stones. If there is any ring grove the finished product has either low spots that are unhoned or the cylinder ends up oversized. If the cylinder is nice enough to Scotchbrite there may be no reason to hone.

It's a judgement call at that piont.
Good luck

We bought the diamond hones, made some torque plates, and are testing the process now. We will keep you informed as to our progress.

Those diamond hones require a lot of pressure. What are you planning on driving those with?

We will be using a Sunnen CV 616 Power hone with adjustable feed pressure.

Thats a sweet machine. Do you all only do porsche work or do you guys work on other makes?

Aircooled 911 based Porsche engines and transmissions only.
No water please!

LOL, I just hope there is water based coolant/lubricant in your honing rig. I much prefer working with water based cutting fluids as compared to the oils.

Tree hungers in California make oil based coolant/lubricating products hard to work with.

By Water I meant "no water cooled cars." :)
Accept this one of coarse.

http://forums.pelicanparts.com/uploa...1088878210.jpg http://forums.pelicanparts.com/uploa...1088878222.jpg

Henry, last spring there was a long post on refurbishing / reusing Alusil Cylinders. Any comments?

I rebuilt my engine before reading any of this. The cylinders measured within specs. I used the green scotch brite you get at the grocery store.
I used a typical 3 stone hone. I wrapped the scotch brite inside the cylinder bore and inserted the hone which bassically added some consistant pressure to the pads. I did use light oil (Can't remember maybe just wd 40 to keep things clean). I ran the drill for 30-40 seconds with an up and down motion.

This was very easy. Unfortunately I had no good info on the process or a tool to measure the surface roughness. Maybe you can do some tests for us alusil guy's.

The results of the thred lead to a procedure used by sunnen with felt pads and paste.

If you have some time look it up. You may have been there already, I havent been on the board for a while.
Good luck on your quest for the truth! I'm behind you all the way!

BTW I've got about 5,000 on the rebuild. Rings seated fine and so far no smoke. Engine's out now because I'm now restoring the rest of the car.

Bill: Your car does not smoke now, did it smoke before the rings seated? I just rebuilt my engine and I get few seconds of white smoke on start-up. I'm hoping it will go away with more mileage.

Only for a minute or so, but I assumed it was assembly lube etc.
Then the only smoke was from main seal leak.
Only other smoke I've seen out of the tail pipe is from rich fuel at startup when it's cold.

So, how can I tell if it's oil or rich?

The smoke is whitish (Unburnt fuel from the cold start valve.), only when cold. I've read this rich. I've seen oil smoke is usually dark/black. Am I right? Disel is black smoke when rich.

that makes me feel better so I will agree. I only have white smoke, and more so since I tweaked my WUR to factory settings.

WOW!!!
 

This information is priceless!
I'm going to be rebuilding my engine in about 10,000 miles. Looking at prices for P\C @ Pelican Parts made my heart sink. Reading this thread though made me feel a whole lot better as well as my wallet. Henry you are amazing!

Thank you guys for the kind words

Oil smoke is white / gray and rich running condition is black. If you've watched Formula One and seen an engine let go, the white plume of smoke is oil.
I was trying to think of a way to easily tell the difference but I am unable to articulate an easy way. If you have white smoke and no oil leaks, keep an eye on your oil level.

As for reringing Alusil, I have no good information about this because I don't do it. I will reuse a matched Alusil cylinder, piston, ring set if they look very nice and the ring gap is within tolerance but when the rings are worn I find another option.
It has been my experience that you will have a hard time finding any rings other that Factory ring from the dealer and they are so expensive that it's not much of an option. Many ring manufacturers ( Hastings, Total Seal and Deves) recommend the same rings for Biral, Nicasil and Alusil cylinders and that just can't be right.
Good luck

Try Gotez and look up the Alusil Thread.

Goetze does make them, but as far as I can tell no one but the dealer sells them. If you guys have another source let me know.

Henry,
Did you get a chance to do the diamond hone experiments?
-Chris

Does Ra tell the whole story?
 

Henry, you did excellent work helping establish some guidelines for us cheapos that want to re-ring nikasils! ;) If you see the piston rings being eaten up on the honed cylinders, it must be the case, so I am not going to argue with that. Your tests further support your observations. It is also great to see what Mahle specifies and delivers in their cylinders.

I have a few thoughts about roughness represented using Ra, and what that may mean for cylinder sidewalls and ring wear.

Note that you could get a huge average roughness, even if there is much flat area (plateau) and only concave scratches, no burrs or peaks. Here is an example (from http://www.predev.com/smg/parameters.htm#Ra%20-%20Average%20Roughness) These three profiles all have the same Ra number!

http://www.predev.com/smg/images/fig43.jpg

It is clear that if you have a surface like the first one or the last one in the figure, you'd wear the heck out of the rings. But if it were a surface like the one in the middle, with much plateau, it may not be bad on the rings at all, even though it has a high Ra value.

Now, I am not a machinist and can not predict what a ball hone will do to a very hard surface. I would just guess that there is little ductility in the material, so there may actually be little smear and more cutting, possibly resulting in a plateau type surface?

If anyone has access to a profilometer that can record the actual profile, I'd be real curious to see them measure Henry's test cylinders. And if you can supply one done with the Scotch brite method, we'd really be rolling! Of course, who's got that much time on their hand?

In the end we should count on Henry's experience over a measurement and theory anyway. Likely, by the time my engine comes apart at over 200k, (knock on wood!) I will have to buy new p&c anyway!

Cheers, George

I think Henry answered the question way back at he beginning. His experience showed that the rings wear out quickly when clean up is done with a flex hone. Its a little puzzeling though as the flex hone is supposed to plateau the surface.

I was hoping that this thread would conclude with a "technical" description of the desired surface when re-ringing Nicasil cylinders with Gotez rings or another brand for that matter.

Has anyone asked Gotez if there is a written statement of surface condition or process they recommend for re-ringing?

I don't discount that processes or methods described in the thread could be correct or even better than what the e.g. Gotez people might say. It just seems like a position from Gotez would be available.

It seems reasonable that Wayne would be able to get an official statement from Gotez or find out that Gotez understands the question but will not give out written instructions for using their products.

If the Gotez info. is on the website, I apologize, please send me a pointer.

-Henry