5?

At the risk of this all getting off course again and the fact that I don't want to post a topic that has been hashed over this much I shall ask a question related to the topic. I have to ask nice as Henry currently has my heads :) . Could someone post a picture of what a deglazed cylinder looks like. There is a very good picture of one before the process and the ones on the test bench have a hand in them so it is hard to see. My cylinders look typlical for the pre-glazed but would like to know how they should look after. I am using scotch brite pads but they are fine grit. I bought red ones but there must be different red ones. I am trying to figure out if I should go buy medium ones. The fine grit removed the oil coating at the base of the cylinder where the piston skirts sit but the very bottom of the cylinder is still rougher than the part where the piston runs. Should it all look the same when completed or will the area where the piston runs still be smoother and be darker.

I used Henry's method with the red ScotchBrite (7337?) pads. I believe they say "Medium" grit.
Goetze rings seated quickly , motor has done about 4k miles since back in service.
I don't exactly have a high end camera to really see the cylinder walls. Only 3 megapixel but maybe this helps?
http://forums.pelicanparts.com/uploa...1165677489.jpg
http://forums.pelicanparts.com/uploa...1165677500.jpg

Dfink,
The term de-glaze referes to the finish that is on the inner surface of the cylinder bore. If it is glazed it looks very shiny (like freshly glazed and fired pottery) and will not cause a new set of rings to seat because of the lack of an abrasive surface. To de-glaze is to roughen up this glossy surface (the topic of this thread) so that there is a set amount of roughness that will help the rings wear in or "seat". This creats a propper seal between the rings, pistons, and cylinder walls.

Sorry if too spelled out, didnt want to leave holes in the answer.

No thats fine. I understand what deglazing is but never with this type of cylinder. With the old V-8 we always honed the cylinder and they came out looking like new the entire surface. It seems with the nikasil you will not get an entirely new looking surface using scotch brite. So I was just wonder how it is supposed to look with this method and if I achieved that with the veryfine grade I bought as opposed to the medium grade. I think mine are probably fine. It has been stated that the scotch brite is not hard enough to actually roughen the surface so I assume all we are really doing is giving it a super good cleaning with the scotchbrite. If I am wrong on this and the medium scotchbrite will actually roughen the surface then I will go out and buy the medium and redo them all.

The purpose of the ScotchBrite is to clean the oil deposits (glaze) from the existing cross hatch in the Nikasil. If your cylinders have no cross hatch left in them (usually 100K miles+) then the cylinders will need to be honed. I recommend having this done professionally with a diamond hone. This will give you the best chance for success.

Remember that honing will remove a small amount of material so check the freshly hones cylinders for consistency and size.
If your pistons were undersized before honing will only make it worse.

They have a really nice cross hatch left. I am pretty sure that even with the fine scotch brite I have them ready to go. I will see if I can get a good picture of the cylinder at the bottom of the cylinder where it is easy to see the difference between the last inch that has never seen wear and the rest of the cylinder. There is now less of a difference since using the scotch brite and soap. I don't think the entire cylinder will every look like that last inch without re-honeing.
Also this may be a good spot to ask this.
Should I leave the cylinders dry or coat with oil. My first feeling is that they should be coated but some have suggested leave them dry to break in the rings. Dry just worries me a bit....

As long as the cylinders are true, it should be possible to do a light hone, just enough to scuff things up, say .0002", but the key is to do it with proper equipment and diamond stones like Henry said. There is no need to coat the bores with oil for storage reasons. It's up to you for assembly - I have seen it both ways - a light rub down of non-detergent non-synthetic oil or a spray of wd-40 on the bores.

OK here are a couple pictures of my cylinders after cleaning. I don't think I want to hone them but do they need more cleaning with the scotch brite. I know it is hard to tell from pictures. I see in the pictures you can see the oil that has gotten into the cylinder from storing the piston in there so maybe not such good examples. The light from the flash really show this. You can't see that normally.

This one show all the way down you can see the ring marks at the top of the piston.

http://forums.pelicanparts.com/uploa...1165792203.jpg

This one (maybe) shows the contrast between the bottom never worn and regular wear areas.

http://forums.pelicanparts.com/uploa...1165792263.jpg

I will suggest it again. The grape style hone. Removes nothing but will put the required scratches back into whatever you are using. Cleans much quicker and better than scotch brite pads and puts some new scratches in the tube for the new rings. T he silicon carbide material is not as hard as diamond but its hard nuff to do the job.

But first you must check dimensions. If its out of round and worn you may need new stuff to fix it.

A picture's worth a 1000 words. Grape or bottle brush hone is too rough by it's self. High ra numbers produce premature ring wear.
104,000 miles
http://forums.pelicanparts.com/uploa...1085762194.jpg

New
http://forums.pelicanparts.com/uploa...1085762209.jpg

Used cylinder honed (grape hone) as per manufacturers instuctions.
http://forums.pelicanparts.com/uploa...1085764857.jpg

I love these threads, were people at all levels offer their oppinions and share their expertise.

Just to add a bit more fuel to the fire and this comes from my experience with BMW cars and bikes.

Nikasil has a Nickel matrix which is fairly hard and ductile, with
about 4% of rather small ~4 micron size Silicon Carbide particles, which in essence is the medium that retains the lubrication in the cylinder.

Now, two other bits of information. The Nikasil coating is normally about .07mm thick or .0025" to .003" and here is the kicker; It is affected by high sulfur content fuels....this is somewhat ofset by increasing the combustion temperatures. Do you all remember the first BMW V8 engines, yes the ones that the Nikasil coating was peeling off.....

So, my experience has been to leave the cylinder surface basically alone, just touch it up with water and Scotch-Brite in the direction of piston movement.

Like it was mentioned before, I'm not trying to convince anyone, just sharing my experience.

I really don't want to stir up the hone don't hone debate. I am not going to hone as I don't own one and I am not going to buy one. I am just wondering if the pictures look like I have done enough or do I still need to perform some more cleaning with a medium pad instead of the fine pad I used. I seem to having trouble locating the red medium pad locally.

Henry, which grit did you use? the grapes come in several grades.

It has been many years since the hone was purchased but I believe it was a 320.
We used the hone recommended by the manufacturer and the honing oil supplied with the hone.

Don't get me wrong, it worked. It gave us a very nice finish and the rings seated well.
It was not until the freshen up that we noticed the excessive ring wear. On the first engine we blamed the oil and the break-in process. The more we saw this phenomena the more we started to understand that the problem was the cylinder surface. After measuring the RA it all began to make sense.
What I am reporting is not written in a book, is not a theory or a wild a** guess. Short ring life as described has been observed over and over again.

--

Its sort of strange as the same process produces longer ring life on many Iron block applications. Are you using moly or chrome rings? I also noted that differen't ring manufacturers specify differen't finish requirements for their rings. I use chrome rings and haven't noticed a difference. But then again chrome rings are usually hard to break in. Moly is soft and breaks in easily. In any case I go with the ring manufactuers specs for their rings.

It could be that the extreemly hard surface in the cylinder dosen't comply easily with the normal ring seating specs and as a result the "normal" ring specs are wrong. The manufacuturer is not going to address this in any case because they want you to buy a new matching set of cylinders and pistons.

How did you determine that there was excessive ring wear? I usually find that the piston land is worn out, much more than the ring itself.

Different materials have different specs.
RA ratings for cast iron cylinders is quite often around 18-20.

We generally use Goetze rings, OE for Mahle Nikasil cylinders.
We also ran Hastings rings and experienced slightly better wear characteristics.

We measured ring gaps to detect ring wear.
Rings gapped between .017-.020" measured .040 to .60 after 15 -20 hours of racing.
Cylinders starting with a correct RA number show less than .005 wear with the same engine hours.

In street engines we see far less ring wear. If an engine is going to see 150K or more which is quite often the case with our rebuilds controlling this initial wear is critical.

Does anyone have a good picture of what a good clean un-honed cylinder should look like. One that has had the scotch brite cleaning.

I certainly don't have Henry's expertise, specially regarding Porsche engines, however, I do agree that with Nikasil cylinders the ring end gap over time in use will give you a good read on the initial condition of the cylinder surface.

Now, can we dig up more information on the subject matter from those out there that have re-ringed Nikasil cylinders?

Actually the thought behind the Nikasil cylinders, in racing that is, was that by making the cylinder surface very hard and the rings the wearable component one could maximize the life of an expensive component and expedite the rebuilding process.

Just picture droping a race engine, popping the jugs and droping a new set of rings (of course, assuming that the short block wasn't damaged), having a new set of heads ready and voila you had yourself a new race engine....

So, we know that a profilometer reading of ~5 RA is what new cylinders come with and ~ 3 RA is what used cylinders measure. So the question becomes, what can be done to used cylinders to bring them to~ 5 RA.

Anyone out there care to chime in....

Well im now faced with this same dilema again, I rebuilt my 3.2 with 140k on the clock last year. The cylinders specked out and had good cross hatch left so I did the scotch brite thingy. This engine as run about 150 miles then got removed for the car to go for a bare metal respray and the engine is now in bits to be converted to a 3.0 MFI engine. Ive examined the piston rings on tear down and it looks to me like the rings failed to seat. The cylinder walls are now very shiny with very little hatch left and the top ring is showing that only about the lower 40% was in contact with the cylinder wall and the lower ring probably only about 10-20% is showing any signs of wear. Is it simply that 150miles isnt enough to make the rings fully contact or has something gone wrong? Engine seemed to run good with no smoke when hot.

Im pretty convinced that these cylinders will need to be re-honed if not re plated. My question is this theres much debate about what if any honing should be used however it obvious that after the cylinder plating is done by the manufacturer they must use some sort of honing process to give there recommended RA, so what are the manufacturers using and why carnt this be used?


Steve