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The Secrets behind Nickies™

How are Nickies™ different from a factory aluminum cylinder?

There were three varieties of aluminum cylinders typically found on aircooled engines. First biral cylinders with aluminum fins cast around cast iron liners. These perform more like cast iron cylinders. Then there were early aluminum cylinders, utilized a ferral sputter or splatter-coat or chromal plating, typically identified by its dimpled bores. Later, Porsche turned to Mahle's Nikasil™ and Kolbenschmidt's Alusil™. Although both were aluminum, that's where the similarity with "Nickies™" ends. So how are Nickies™ better?

 

Nickies™ have more surface area
Nickies™ have twice thermal conductivity of factory cast aluminum cylinders
Nickies™ have a minimum 50% greater tensile and ultimate yield strength than factory cast aluminum cylinders
Nickies™ are stronger and more ductile than any cast cylinder
Nickies™ increased strength and ductility allow for larger bore sizes and larger slip-fit cylinders than previously possible.
Nickies™ come half-mooned for improved crankcase windage, which is typically good for 8-10 horsepower over non-mooned cylinders. Mooning factory cylinders can be a time consuming and costly process if you damage the Nikasil plating.

 

Case Study: What makes Nickies™ the latest step in the evolution of the aircooled cylinder?

Cast cylinders vs. billet OE cast aluminum cylinder vs. Nickies™

While developing Nickies™ cylinders, we considered various casting materials and processes. Even with the best of castings, there are limitations. Stock cylinders were cast. While advantageous for mass production, there are downsides to casting. First, casting poses a big difficulty to a strong grain structure. The strength of a cast cylinder is limited by the casting alloy used, as are other critical properties that affect a cylinder's performance. Our alloy, especially extruded for LN Engineering by Alcoa, allows for the greatest strength, best grain structure, increased ductility, and thermal conductivity. Through advanced metallurgy, material science, and engineering, LN Engineering's Nickies™ cylinders provide:

  1. Increased Strength: The material used in stock cast aluminum cylinders has a tensile yield that varies from 36k to 42k psi. Through our close work with Alcoa and advances in plating technology, we have developed an alloy that both exceeds the strength of stock cylinders and has excellent adhesion for the NSC process, which is essential for longevity. Each batch of our custom extrusion goes through intensive QC and is up to 50% stronger than cast aluminum alloys used in OE cylinders. Our alloy is up to 35% stronger than cast iron alloys which are known for great thermal stability, making our cylinders the best available!
  2. Increased Cooling: We achieve this through a doubling of thermal conductivity with our custom alloy over the casting alloy used in stock cast aluminum cylinders. Nickies™ have up to 400% increase in thermal conductivity over cast iron cylinders too. Paired with these improvements in material science, most cylinders have increased surface area and fin count, up to an extra 65% more surface area and 6+ fins per inch (except on 930 and later cylinders which use a different fin configuration, shown below).
  3. Increased Ductility: Combined with the above properties of our exclusive alloy, our Nickies™ are extremely ductile, allowing for thinner cylinders and larger bore sizes than possible with any cast cylinder, all while maintaining reliability and longevity expected from our Nickies™ cylinders.

Porsche 930 Cylinders

Who uses Nickies cylinders?

Most every well-known engine builder in the United States uses Nickies cylinders for their high-end rebuilds and race projects and many more sets are exported by resellers like EBS Racing internationally for street and race projects. Just ask for Nickies by name. We have a strong proven track record of impeccable quality and performance that is untarnished as well. Most builders once they use our cylinders, keep on using them, only resorting to OE parts for stock rebuilds, where price points may be the only reason not to use Nickies. However, in most cases, Nickies are cheaper than factory replacement or Motorsports sets.

Why use JE Pistons with Nickies cylinders?

Where a Mahle piston best suits a Mahle cylinder, the proprietary alloy used for our Nickies™ cylinders is designed for optimal piston to cylinder clearance using JE's 2618 aluminum alloy forgings.

Why have I heard complaints about JE Pistons?

A few years back JE had a few problems with one particular forging, but it was quickly remedied with a new forging and revised pin oiling setup. But this was for a very small group of bore sizes and limited applications. In fact, most of the issues we have observed are from running the clearances too tight when using a JE Piston in a factory Mahle cylinder. In the better part of a decade, cannot say that we can attribute a single failure to use of a JE Piston, as a Mahle piston would have likely failed in the same scenario. Likewise, we have seen Mahle pistons suffer similar wrist pin boss failures, so no piston is immune. The other issue common to both Mahle and JE pistons is that in race use, they hour out, meaning after so many hours, they should be replaced.

Why no sealing rings or provisions for o-rings?

Although some factory Porsche cylinders have provisions for head gaskets, sealing rings, or o-rings, our Nickies cylinders do not come with any for several reasons. We've found through evaluation of cylinder failures, that these sealing ring grooves cut into the sealing surface of the cylinder at the head can leave the cylinder prone to failure due to the thinner cross section of aluminum left to seal against the head.

Likewise, we've found that o-ringing the case or cylinders at their bases rather than using sealant eventually leads to nagging oil leaks down the road. Use of Curil T or Curil K2 is a time-proven solution to sealing cylinder bases.

For those requiring these provisions, we can add them to any cylinders for a small surcharge.

How does availability of Nickies and JE Pistons compare to OE?

LN Engineering stocks most popular Nickies and JE Piston sets from 2.0 liters to 4.0 liters for immediate delivery. If we are out of stock or a custom set is needed, normal lead time is 4-6 weeks, but typically less.

Furthermore, LN Engineering offers many piston and cylinder sets that are either no longer available (NLA), were only available as factory racing sizes, or even more importantly, never before available, all at prices very competitive in the industry. A good example of this is the poor supply of factory replacement and Motorsports P&C sets, leading to prices that can be thousands of dollars higher than a superior set of Nickies and JE Pistons.

The JE Pistons sold by LN Engineering differ from those sold by other vendors or even JE Pistons directly, as we include options like coated skirts and others standard. Additionally, we stock many sizes and compression ratios not available from any other source.

How does the plating used on Nickies differ from Mahle's Nikasil™?

Historically, the first way to allow the use of solid aluminum cylinders was developed in 1951 by Mahle. This was "Chromal", which used a hard chrome plating on the bore of the cylinder. Many aircraft have since used this over the years, too. The big problem with this plating is that it is highly prone to chipping - although in a low-performance, light-duty, low rpm aircraft engines it proved satisfactory, these chrome platings did not fare so well in engines turning higher RPMs. In addition, chromal platings tended to shed oil, required cylinder walls to be "dimpled" to force oil to stay on the cylinder walls. This also leads to flaking or cracking of the plating. Similar in wear characteristics to cast iron, Porsche used a thin flame-coated (also known as sputter coating) "ferral" coating. Needless to say, this is an unsatisfactory solution, and it ultimately led to Mahle's development of Nikasil™ in 1967. To this day, high end Porsche engines utilize this Nikasil™ plating process. Not only does Nikasil™ allow the total elimination of poor-cooling cast iron, but it also is harder and more oleophilic (oil-liking) than cast iron. In fact, diamond tooling is required to hone these cylinders! This allows superior lubrication, reduced friction, and superior wear characteristics. We feel so strongly about our NSC nickel silicon carbide composite plating process, that all our cylinders come with a limited lifetime warranty on the plating. No cylinder commercially available comes with that promise!

Here are some examples of replacement cylinders sold by other European cylinder manufacturers and their inferior plating/coating:

Bad Nikasil coating  pic. 1 Bad Nikasil coating - example 4
Bad Nikasil coating on european aircooled cylinder - pic. 2 Bad Nikasil coating - example 3
Bad Nikasil coating - pic. 3 Bad Nikasil coating - example 2
Aircooled cylinder plasma coating peeling - pic.1 Bad Nikasil coating - example 1

Is Alusil™ the same as Nikasil™? Which one is better?

Nikasil™, or it's similarly performing NSC (nickel silicon carbide composite) plating, while the best solution around, it is also the most expensive. Reynolds and Kolbenschmidt developed a process that still uses cast iron or similarly clad piston rubbing on an etched high-silicon aluminum bore. The Chevrolet Vega was among the first of the vehicles to use this new material technology. Needless to say, the Vega did not have a good reliability record and only limited 2.7 and 3.0 liter 911 models adopted Alusil™ cylinders, later replaced by Nikasil™ cylinders except on water-cooled models. Porsche's newest Boxster and 911 models use a modern version of Alusil™ called Lokasil™ while Porsche models like the GT2, GT3, and Carrera GT still utilize Nikasil™ platings in their bores.

There is quite some debate concerning the re-useability of Alusil-™ type cylinders going back to the etching/honing process done to the raw aluminum bores and re-ringing. This is not an issue with Nikasil™, as it can be readily re-honed or stripped and replated if required. An Alusil ™ cylinder can also be plated with a Nikasil™ or NSC-platings to allow reuse of these type of aluminum cylinders with conventional pistons and rings.

Why use our NSC plating?

Aluminum pistons rubbing on raw aluminum cylinders doesn't work. Originally developed by Mahle, the Nikasil™ process used by Mahle or our similar silicon carbide composite NSC plating, consist of silicon carbide in a nickel matrix. Silicon carbide is used partly for its uniform particle size, and partly for its hardness. Silicon carbide is second only to diamonds in hardness and therefore provides excellent wear characteristics. The reason diamonds cannot be used is their high cost and the fact that we would have no way to hone it. NSC particle size is a Gaussian distribution of about 3 microns. This size is important so that the coating will not affect the internal components of the engine and too large of a particle will affect ring wear. Another major reason that silicon carbide is used is that it is oleofilic or it has a natural tendency to absorb oil, which in turn helps the oil retention of the coating. The NSC coating is an electroplated process that uses an electrical current to adhere the nickel and silicon carbide molecules to the aluminum. The process does involve dipping the entire part into the plating solution, and an electrical current must be present to start the plating process. Coating thickness varies with each cylinder and is determined by the amount of time it is in the tank as well as the amount of power used. The industry standard of plating thickness is between .003" to .005". Due to the hardness of the coating and its silicon carbide content, we must use diamonds to hone the cylinder bore. An important part of honing the coating is to provide a proper surface finish. If too rough, ring wear will be harsh, and if too smooth, the rings will not seat properly. Oil retention in the bore can also be negatively affected if the crosshatch is not the proper depth. A surface profalometer is used to check the roughness average (RA) and the depth (RPK & RVK & RK ) of our honing patterns to ensure proper engine performance and can be ordered in Ra varying from 3-4 to an average of <20. We feel so strongly about our NSC process, that all our cylinders come with a limited lifetime warranty on the plating. No other manufacturer has such a warranty.

I've heard of problems with Nikasil™ and high sulfur fuels in the US.

Refining the Alusil™ process is a major focus of automotive engineering today due to the price and complexity of Nikasil™ plating, hence the proliferation of Lokasil™ or similar high-silicon etched aluminum blocks used by many manufacturers . Some attempts to modify the tried and true, yet expensive, Nikasil™ process resulted in chemical incompatibility with high-sulfur fuels. It seems that there simply is no way to make it cheaper without compromising quality and durability. BMW had problems with their 8 and 10-cylinder aluminum Nikasil™ blocks as did Jaguar in the US where the fuel has a high sulfur content, whereas Porsche had zero problems in the 2+ decades Nikasil™ was used. Many also neglect the fact that BMW also uses Nikasil™ in their motorcycles, to this day, without fail. Peeling coatings can be caused by many factors including improper prep or poor plating response of the aluminum alloy used. When the coating is applied properly the nickel will bond stronger to the aluminum than the aluminum bonds to itself or about 25,000 psi. In other words, the coating has higher tensile strength than the aluminum does. Because of this bond, when seizure occurs and plating comes off, there is often aluminum that comes off with it. Coatings will most often peel as a result of substandard materials being used, or when a processing error occurs. The best solution is to use the best materials possible and to monitor the plating process very closely and to have good quality control checks to ensure each and every Nickies™ cylinder performs up to its expectations.

Why have I heard there aren't any good rings for use with Nikasil™ or NSC-plated bores?

Considering the wide range of bore sizes we've made our Nickies cylinders in, it's been critical to find rings that are designed to work with nikasil. In fact, we have quite an extensive array of ring sets from Porsche's original equipment manufacturer, Goetze, to many that are supplied by JE Pistons and other ring manufacturers. In fact, we typically use lighter tension, thinner rings, which seal better and wear better than the higher tension rings typically used with cast iron bores. Even chrome rings can be run on our NSC plating, which has shown excellent compatibility with many low-tension chrome rings. Total Seal now even offers many rings designed for use with exotic platings, like Nikasil or NSC-plated bores, as found on our Nickies.

What’s Wrong with Cast Iron Cylinders?

A quick survey of performance aircooled engines will find that VWs are unreliable, but the Porsche 911 is so reliable that in both production and racing they last forever. Why? Keep reading and find out!

VW Typ 1 cylinder cast VW Typ 1 cylinder cast

All VW, Porsche 914, and early Porsche 911 models use cast iron cylinders. One of the major problems with cast iron cylinders is that they are thermally overloaded! Note that the aforementioned 911T has the only 911 engine ever to receive cast iron cylinders due to its detuned, low performance nature. These engines, at their maximum 2.4L, had just an 84mm bore and produced about 22hp per cylinder, and that’s with a superior cooling air system. Even Porsche realized that cast iron cylinders were not sufficient with their early adoption of biral, ferral, chromal, and later Nikasil™ plated aluminum cylinders on Porsche engines. It should now be apparent why the challenge of keeping your aircooled engine "cool" is a daunting task!

 Cast vs. Billet - It's easy to see why Nickies™ work so well. Cast vs. Billet - It's easy to see why Nickies™ work so well.

Why Aluminum Cylinders?

Although biral cylinders are a significant upgrade over cast iron cylinders, Porsche started using solid aluminum cylinders all the way back in 1951 in its production cars, before cast iron and later biral-type cylinders were first used on later Porsche 356 and 912 models followed by 2.0 through 2.4 liter 911 models. a cylinder with better cooling was still required for performance models- they turned to solid aluminum cylinders to fill that need for added cooling and longevity! Aluminum conducts heat FOUR TIMES as well as cast iron.

I've heard of biral cylinders. How do these perform?

Porsche tackled this problem by using “biral” cylinders to overcome the limitations of cast iron ones up to 32hp per cylinder. Rather than be solid cast iron, these are a cast iron liner with aluminum cooling fins. Clearly, this is a big step in the right direction. Although this is a step in the right direction, birals suffer from a multitude of problems ranging from wash-boarding and warping, to separation of aluminum from cast iron, leading to heat soak and overheating.

Although biral-type aluminum finned iron-lined cylinders do typically cool better than cast iron cylinders, the superiority of these cylinders ends here. From a cooling standpoint, this is a step in the wrong direction. Although the iron or ductile-iron liner is stronger, it has a much lower thermal conductivity than a fully aluminum cylinder. Iron or biral-type cylinders have higher friction coefficients and as such, wear faster than Nikasil™ or NSC-plated aluminum cylinders do, on top of not cooling as well as fully-aluminum cylinder.

Nickies™ are 35% stronger than the best ductile iron available, debunking the myth that steel sleeves are needed for strength. Nickies™ also make more horsepower!

There is no finer cylinder available for your aircooled engine than LN Engineering's Nickies.™

Interesting factoid: LN Engineering once offered biral-type cylinders, dubbed "Biral Babies," (shown above) as an alternative to our Nickies.

Case Study: How do you solve the problem of thermally overloaded two-cylinder small aircraft engines?

2-CYL Experimental Aircraft Nickies™ 2-CYL Experimental Aircraft Nickies™

LN Engineering was approached by a small-aircraft manufacturer with a desire to have a two-cylinder alternative to typical four-cylinder power plants in their Ultra-light and Experimental aircraft. There were three primary objectives:

Reduce total engine weight: using Nickies™ reduced total engine weight by over six pounds.

Increase reliability: This is a two part objective. Primary objective was to double TBO from 1000 hours to 2000 hours. Secondly, 1/2 VW platforms seem to have higher than normal head temps and oil temps. Nickies™ greatly reduce both allowing for longer bearing life as well as valve guide and seat life.

Increase horsepower: Current 1/2 VW platforms peak out around 40 HP, if heavily modified, but no not cool satisfactorily for extended use. Our two-cylinder horizontally opposed air-cooled engine was dyno tested at 49 HP @ 2900 RPM while running cooler cylinder head and oil temperatures than a stock air-cooled type 1 vw engine.