do I need to hone this?

[Porsche_monkey]

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

[Henry Schmidt]

[KobaltBlau]

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!

[cerberus]

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?

[Henry Schmidt]

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.

[Wayne 962]

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

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

-Wayne

[Doug Zielke]

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

[ChrisBennet]

Thanks Henry!
-Chris

[Henry Schmidt]

Try rutland Tools or possibly Ebay?

[Jeff Alton]

Henry, thanks for all the info.

Cheers, Jeff

[Steve@Rennsport]

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,....

[echrisconnor]

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?

[Henry Schmidt]

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.

[KobaltBlau]

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!

[Henry Schmidt]

Originally posted by KobaltBlau
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.

[echrisconnor]

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

[350HP930]

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.

[mike95125]

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!

[Henry Schmidt]

Originally posted by echrisconnor
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

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

[Henry Schmidt]

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