nikasil cylinders?

[77targa]

The nikasil cylinders are slightly magnetic correct? can they be honed and reused

[Bobboloo]

I've heard they are magnetic but I've honestly never tested their magnetivity. I can always tell the difference between Nickasil and Alusil just by looking inside the cylinder. Nickasil looks like a nickel (dark and somewhat shiny) Alusil has a dull gray/clay appearance.

Nickasil are very durable. They can and are re-used quite often provided they are within spec. If they are out of spec they can still be bored and re-plated with an added plus of gaining a displacement increase.

Honing is done with a Nickasil specific grape type hone, that has Aluminum oxide abrasives, with good results.

[Rot 911]

Yes they can be honed and reused.

[fredmeister]

Originally Posted by Bobboloo

I've heard they are magnetic but I've honestly never tested their magnetivity. I can always tell the difference between Nickasil and Alusil just by looking inside the cylinder. Nickasil looks like a nickel (dark and somewhat shiny) Alusil has a dull gray/clay appearance.

Nickasil are very durable. They can and are re-used quite often provided they are within spec. If they are out of spec they can still be bored and re-plated with an added plus of gaining a displacement increase.

Honing is done with a Nickasil specific grape type hone, that has Silicon abrasives, with excellent results.

How durable is the replating once it is rebored and who is the recommended supplier/shop?
I thought the Nikasil process was done during the casting process of the cylinders and was not really a plating process after the fact.
Also, how durable are the JE aftermarket pistons you will likely have to run with these?

[Bobboloo]

I don't have first hand experience using re-plated Nikasil. Henry Schmit (Supertec) or Steve Weiner (Rennsport) could offer some feedback but Nikasil is indeed a plating process. Mahle Nikasil cylinders are made of an aluminum alloy and are then plated.

Engine Builders Supply and LN Engineering both offer bored and re-plated Nikasils. U.S. Chrome is one of the platers out there and I'm sure there are others.

Again, I don't have the experience of guys like Henry, Steve or John Walker but my understanding is that Mahle is the most durable piston available for Porsches but that JE's can also offer a long life if they are matched correctly. JE has different alloys you can choose from and choosing an alloy that best matches the thermal expansion rate of the cylinder you're using allows you to run the smallest gaps which translate to the longest life. Charles Navarro (LN Engineering) is the guy to speak to on thermal expansion rates. He's done lots of research for his "Nickies" which are Nikasil plated billet aluminum cylinders. He uses JE almost exclusively for his cylinders.

[Flieger]

+ 1 on the Nickies - they are a great Aluminum alloy and are stronger (billet vs. cast) than Mahle. They are matched thermal expansion rates to JE piston alloy so they have tight tolerances unlike Mahles + JE. The cylinders also look better than the rough cast look.

Alusil was the process of a high-silicon Aluminum cast and etched to reveal a Silicon wear surface. Nickasil is cast Aluminum then plated with Nickel-Silicon-Carbide for the wear surface.

[Scott R]

I had Nikasil on my 3.0, however no amount of honing would solve the fact they were too far out of spec to re-use. Make sure you have them measured.

[fredmeister]

Originally Posted by Flieger

+ 1 on the Nickies - they are a great Aluminum alloy and are stronger (billet vs. cast) than Mahle. They are matched thermal expansion rates to JE piston alloy so they have tight tolerances unlike Mahles + JE. The cylinders also look better than the rough cast look.

Alusil was the process of a high-silicon Aluminum cast and etched to reveal a Silicon wear surface. Nickasil is cast Aluminum then plated with Nickel-Silicon-Carbide for the wear surface.

Thanks for the info, Alusil is the cast method......explains why is it cheaper than Nicasil.
One other thing, heat transfer rates are better with Nickies since they have more cooling fins per cylinder since you can machine thinner fins than OEM cast liners.
Amazing that someone will machine those out of a lump of aluminum.

[Flieger]

I think the machining is done by a Computer-Numerically-Controlled (CNC) Machine Mill

[fredmeister]

Still a nice piece either way......too bad you don't see them on the engine when it is running in the car.

[Bobboloo]

I was recently doing some reading up on the process of "honing" Nikasil and wanted to address an error in my original post. I wrote "silicon carbide" where I should have written "aluminum oxide". Silicon carbide stones are used for honing iron cylinders.

The grape hones that are sold for Nikasil cylinders, by companies like Engine Hone, are made of Aluminum oxide not silicon carbide because it's softer than silicon carbide. What you actually are doing with an aluminum oxide hone on a Nikasil cylinder is de-glazing not honing. De-glazing can also be done with a Scotchbrite pad for what it's worth and you don't run the risk of tearing the plating at the edge of the bore.

It seems silicon carbide hones aren't hard enough to actually hone a Nikasil cylinder but they can damage the cross hatches which is not good. To actually "hone" a Nikasil cylinder you need diamond stones and a machine like a Sunnen that can apply enough pressure and keep the stone on axis.

It seems the best thing with used Nikasil is to mic them to see if they are in spec and if they are de-glaze them. If they are out of spec or the cross hatch is worn off then send them out to be re-conditioned (bored and re-plated) by someone like Langcourt or you could send them to LN Engineering who uses Millennium I believe.

One more thing. Re-plating doesn't seem to be quite as good as a new set of Mahles because they can't seem to get the cylinder absolutely clean of contaminates. Consequently the plating doesn't really "stick" as well. Also Mahle doesn't cut corners. They make sure the plating has the right amount of silicon and they wrote the book on Nikasil.

[Zeke]

So, the question that begs is what engines had which type of cylinder? And which years had both? I only know that up thru circa '73 they were cast iron with a steel sleeve.

[Bobboloo]

I only know 70' thru 89' first hand.

70' thru 73':

Cast Iron for the T
Biral (Iron cylinder inside aluminum) for the E and S

73' RS Nikasil

74' thru 89' Nikasil or Alusil.

[Zeke]

Originally Posted by Bobboloo

I only know 70' thru 89' first hand.

70' thru 73':

Cast Iron for the T
Biral (Iron cylinder inside aluminum) for the E and S

73' RS Nikasil

74' thru 89' Nikasil or Alusil.

Ah, yes, I did forget about the birals. But, did the factory just grab whatever they had nearby on the engine ass'y line?

[Bobboloo]

Originally Posted by milt

Ah, yes, I did forget about the birals. But, did the factory just grab whatever they had nearby on the engine ass'y line?

Are you referring to Alusil vs. Nikasil? I would think that Alusil is cheaper to manufacture since it isn't plated. Plating adds more time and money to the process. Then again, when you think about it, the piston is plated, for the Alusil set, but I guess it's still cheaper because the piston doesn't have to be honed. The plating in a Nikasil cylinder has to be honed so maybe that's the cost difference.

My guess is Porsche was aware of the durability of Nikasil over Alusil from racing but also seized the opportunity to make more profit by lowering cost through the use of Alusil for street motors.

I bet they never put Alusil in the 74' thru 77' Carreras or Turbos since they were considered top of the line.

It is interesting, however, that they still used both types throughout production until sometime near 89'.

[Zeke]

Originally Posted by Bobboloo

It is interesting, however, that they still used both types throughout production until sometime near 89'.

Well, that seems to be the case here.