997 Lokasil Alusil Nikasil

[HKZ Bob]

Hi Forum, who can tell me more about cylinder wear with Lokasil & Alusil coating

compared to Nikasil coating.

I have heard a lot of engine damage on Lokasil/Alusil coated engines.

Here some pictures.




BR
Bob

[HKZ Bob]

Wow all our engine rebuilders in silence?

[HKZ Bob]

Some real evidence data what can happen on your 997/ 996

Pictures were made with an endoscope through the spark plug hole and shows
line damage.

This is seen an all 6 liners. (Lokasil/Alusil coating)

[tharbert]

Cant answer but thought describing each process would help:

"n Nikasil: An aluminum engine is dunked in an electrolytic "bath" of free-floating nickel, silicon and other junk. The electrolytic action causes these hardy substances to adhere to the aluminum surfaces.

"It does work very well in a lot of applications," admits one engineer philosophically behind iron liners. But Nikasil's main drawbacks are serious.

First, says Achim Sach, of VAW Motor GmbH, a part of the VAW Group aligned with Mexican casting giant Cifunsa SA, "Nobody wants to have nickel in the plants anymore." Also, as noted in September, high-sulfur fuels eat away at the coating, eventually rendering it useless. Result: ruined engine. And Nikasil has "throughput" issues: The block has to be labor-intensively "masked" before it takes a Nikasil bath, so that the particles cling only to the bore surfaces. And the block has to soak for more than an hour, claim some skeptical sources. Nikasil appears to be on the skids for these reasons. BMWhas abandoned the process. Jaguar Cars and Ferrari SpA still like it, though.

n Alusil: The engine block is fashioned from high-silicon content aluminum alloy. The block undergoes initial machining, then, similar to Nikasil, is dipped in an acidic bath that etches away the aluminum on the bore surfaces, exposing the durable-wearing silicon.

Again, however, there are considerable problems. Alusil blocks must be made in a slow, low-pressure process, says Mr. Sach, and the original alloy itself is more expensive. He believes Alusil is good for low-volume use where cost and manufacturing speed are not the priorities.

Alusil's cost might be bearable even for mainstream vehicles, but a foreign automaker engineer insists, "Throughput time is not acceptable for high-volume lines. We would never consider this process."

n Lokasil: Promoted largely by casting-kahuna Kolbenschimdt Pierburg AG, Lokasil is a "sacrificial" bore liner comprised of silicon fibers in a binding that, when inserted into the block mold, burns out the fibers, leaving the high-content silicon surface directly in the bores.

The Lokasil process is acutely effective. But it also is laborious - slow squeeze-casting is required - and expensive. Currently, Kolbenschmidt's sole customer for the process is Porsche AG.

n Finally, there is spray coating - thermal or plasma - and laser etching. Thermal and plasma spray coating, as a technique, has knocked around for some time; Sulzer Metco believes it eventually can be a prime force in the bore-coating industry. In one spray-coating method, a wire comprised of the material with which you'd like to coat the bore surface is heated and the "droplets" produced essentially are blown in a controlled fashion onto the bore surface.
"
Attribution

[Steve@Rennsport]

From experience with these things,...

Nikasil has been VERY successful in air-cooled cylinders. NASCAR engine builders use it as does many F1 engines. I cannot explain why only BMW suffered erosion problems with their V-8 engines since they never released any data. I've yet to see any Porsche one exhibit the same problems that the 4.0 BMW's did.

Alusil has also been quite successful in 911's. The only issue is that pistons need a special iron coating to prevent galling. This does limit replacement options without re-plating with Nikasil.

Lokasil is an inexpensive alternative to the above processes, but I think the database is yet incomplete regarding long-term durability. It appears to be unaffected by high-sulfur fuels, thus far.

Naturally, JMHO.

[HKZ Bob]

Dear all,

in Germany there are a a lot of customers who complaining of heavy oil consumption on their 997 or
major engine blow-ups.

Of course they are driving top speed with their vehicles. That might be different to the US usage.

Here some links in German language.

PoPoTec über Beschichtungen

Porsche 997: Ab welchem Baujahr oder MotorNr. wurde Nikalsil Beschichtung eingesetzt - Porsche 911 997 Forum / Kaufberatung von PFF.de

[bh912e]

944's are alusil, so this is nothing new. In my opinion this is a great system, low tension piston rings with tight piston to cylinder tolerance , ferrocoated pistons. However in today's engines which are constantly after horsepower and efficiency there are some issues with many modern engines which can hurt longevity. Small skirt, low drag pistons; fuel/emissions systems that modify engine running parameters to put heat into the catalyst for reduced emissions, and the use of super thin film low viscosity oil for reduced drag and increased efficiency. All of these make a great running, efficient motor but this doesn't equate to longevity.

[Walt Fricke]

Bob

It appears that once a Lokasil block is worn, scratched, ovaled, or otherwise not within specifications, all that can be done to it is to have it resleeved with Nikasil surfaced liners. And purchase pistons which are compatible with Nikasil. See LN Engineering for information on this.

A lot more expensive than dealing with cylinders which sit, separately or as a group of three, on top of a case.

For the air cooled motors, if you have worn Alusils you throw the pistons away, buy new ones suitable for Nikasil, and have your Alusil cylinders Nikasil plated and machined to fit your pistons.
Pretty straight forward.