Nikasil Replating

[patkeefe]

Anyone got any idea what it costs to have cylinders replated with Nikasil? And, what is a good shop to get this done by?
Thanks!
Pat

[nabilious]

Hey Pat- I too am looking for a place to do this, I know that EBS (porsche parts place) does this but they send them out for it. I've read of a place in Wisconsin that specializes in this but I don't know the name or #. i'll get on this as I have some cylinders that need doing
Nabil

[Shuie]

Call EBS

[dd74]

Don't JE Pistons require that the cylinders get replated with Nikasil?

[tshih]

If you knew how the Nikasil process is actually done, you won't be asking how to "replate" them. One doesn't replate those cylinders since they are essentially worn off and are then disposable (usually after many hundreds of thousands of miles). The cylinders are cast with a special aluminum, nickel, silicon alloy. Then they are treated chemically with a sodium hydroxide solution at the bores to dissolve away the aluminum part of the alloy leaving the nickel and silicon parts behind exposed to the surface. The chemical properties of Ni and Si are hardness, toughness, and good wearing. Since these particles at the surface are embedded in the rest of the remaining aluminum alloy, once they are worn off you would essentially have to recast them in before you can get a new surface. One might as well start from scratch and make new cylinders from a costs efficiency viewpoint. What I don't know is if one were to treat the existing worn out cyclinders after boreing them larger with the lye solution to expose fresh Ni-Si does one then have a new (but larger bore) Nikasil cylinder?

[carmad]

EBS, I think it cost about $125 per cylinder.

[350HP930]

Originally posted by tshih
If you knew how the Nikasil process is actually done, you won't be asking how to "replate" them. One doesn't replate those cylinders since they are essentially worn off and are then disposable (usually after many hundreds of thousands of miles). The cylinders are cast with a special aluminum, nickel, silicon alloy. Then they are treated chemically with a sodium hydroxide solution at the bores to dissolve away the aluminum part of the alloy leaving the nickel and silicon parts behind exposed to the surface. The chemical properties of Ni and Si are hardness, toughness, and good wearing. Since these particles at the surface are embedded in the rest of the remaining aluminum alloy, once they are worn off you would essentially have to recast them in before you can get a new surface. One might as well start from scratch and make new cylinders from a costs efficiency viewpoint. What I don't know is if one were to treat the existing worn out cyclinders after boreing them larger with the lye solution to expose fresh Ni-Si does one then have a new (but larger bore) Nikasil cylinder?

You are incorrect and are confusing alusil cylinders with nikasil.

[carmad]

This is what they looked like when they came back.

[patkeefe]

Looks nice, Julian!

[carmad]

The cylinders were in good condition before I had them re-plated, about 63,000 miles, you could still see the original honing marks. I had one cylinder with some slight pitting due to corrosion, so decided to have all six done. EBS requested I send in the pistons as well to optimize the clearance for each piston/cylinder combination.
Have put about 6'000 miles and several DE days on the engine, very strong makes about 385-400 hp, no issues yet.

[tshih]

350HP930,

I am not confusing Alusil with Nikasil. Why do you say I'm wrong . Please provide proof to the contrary. What appears to have been done here is plating the cylinders with Nickel. If you have some understanding of chemistry how do you introduce silicon into the plating process? Chemically it is easy to plate nickel onto aluminum. The surface is then a thin layer of nickel (which is harder than steel or aluminum but not as hard as Ni-Si (an alloy of both nickel and silicon).

[RickM]

I believe Souk has a Nikasil replating service. You may want to ask him for more info... www.motomotions.com

[ROWSC]

Check out this site for information on the process. I had US Chrome bore and plate my Nikasil cylinders and the total price was $1,300. They came HIGHLY recommended by certain nameless engine builders.

http://www.usnicom.com/The_Product___Process/the_product___process.html

[350HP930]

Originally posted by tshih
350HP930,

I am not confusing Alusil with Nikasil. Why do you say I'm wrong . Please provide proof to the contrary. What appears to have been done here is plating the cylinders with Nickel. If you have some understanding of chemistry how do you introduce silicon into the plating process? Chemically it is easy to plate nickel onto aluminum. The surface is then a thin layer of nickel (which is harder than steel or aluminum but not as hard as Ni-Si (an alloy of both nickel and silicon).

I am saying you are wrong because you are. The etching process you describe is the way the silicon crystals in an alusil cylinder's surface are exposed, not nikasil. Nikasil is diamond honed for its final surface, not etched. The embedded crystals in nikasil are carbide, not a nickel silicon alloy.

From what I have read the carbide particles that are trapped in the electroplated nickel matrix are initially suspended in a slurry electroplating solution. As the nickel builds up the small carbide particles in the solution are trapped in the forming metal.

Once the plating process is complete they are honed and that is the end of the story.

The main reason the carbide is added is for oil retention. Nickel plated cylinders long predated nikasil but they had problems due to the fact that plain nickel does not retain oil well. The carbide added to nikasil is what makes it as good as it is by improving both surface hardness and oil retention.

Its likely that the aluminum cylinder is acid etched before the plating process since that is SOP for good surface bonding when electroplating, but it has nothing to do with exposing silica particles as is done for prepping alusil cylinders.

If you don't believe me do the research on the subject.

[Early_S_Man]

tshih,

350HP930 is quite right!

I suggest you peruse any of Paul Frere's books to get an engineer's perspective on Alusil vs Nikasil mfr processes.

[tshih]

I don't see why there can't be a similarity in Alusil and Nikasil technology. Alusil by name implied no nickel content in the alloy. Nikasil may have silicon carbide imbedded in the walls of the exposed cylinder. Those particles are exposed by the same process of leeching away the aluminum content in the alloys of both alusil and nikasil. The diamond honing process is needed to smooth out the walls of the nikasil and can also be used for alusil. Diamond tooling for hardened materials is not novel and is not part of the equation as to whether one can replicate the nikasil once the original walls are worn down (as the thread was started).

I did read the Frere's chapter on cylinder engineering and I am not mistaken in my posting.

As to the reason "the carbide is added for oil retention" is incorrect. The carbide is the material which gives the walls the hardness factor (Mohr scale about 9.5 versus 10 for diamond) and not for oil retention. On a microscopic level if you magnify the walls of the nikasil cylinder you would see the uneven grains of carbide/nickel sticking out from the bed of aluminum metal like closely cropped hair on skin. The unevenness is probably where the oil will stick to as opposed to the super-smooth walls of pure nickel plating.

[island911]

Paul Frere's book
Early_S_Man
350HP930
.
.
.
yet my money is on tshih being right. hmmmm ....

Pls continue. ..

[island911]

not going to take the bait, eh?

Well, heres what I found out:

Nickel Composite Coatings – Apticote is a tradename for Poeton and NICOM is a tradename for US Chrome. This is an electrolytic nickel composite coating using nickel as the matrix to dispurse silicon-carbide particles evenly across a bore surface so as to provide a load bearing wear resistant surface. The German Mahle company calls their coating NIKASIL and Kolbenschmit calls theres LOCASIL. They’re all the same thing, no matter what their ads say about ceramic this or composite that, its all essentially a 30 year old technology first pioneered by US Chrome.

That, and you want a very thin coating of the stuff, as its thermal conductivity is much lower. (certainly wouldnt want the parent structure to be made out of the nikasil)

Oh, and chemically etching seems the way to go ... .diamond honing doesn't work so well.

[MotoSook]

[MotoSook]

Part 2: (sorry...I'm trying to cut all the fat off and post the good stuff)