Nickies Cylinders for Aircooled Porsche and VW Engines
LN ENGINEERING IS PROUD TO OFFER NICKIES™ CYLINDER AND PISTON SETS FOR AIRCOOLED PORSCHE ENGINES- THE ULTIMATE PERFORMANCE AND RELIABILITY UPGRADE
It is not always that you hear high performance and long life paired together, especially when referring to performance aircooled Porsche or VW engines. It is very typical, even with high-powered 911 cooling systems, that high-performance engines run too hot, and as you know heat kills! Higher operating temperatures result in a thermally overloaded engine that, among other things, has cylinders that fail to seal against the head and have significantly shorter life spans versus stock displacement engines.
Nickies™ cylinders reduce cylinder head and oil temperatures while providing durability exceeding that of OEM Mahle Nikasil plated cylinders, even with increased output levels due to increases in displacement, compression ratio, or boost.
LN Engineering Nickies cylinder and piston sets are available for Porsche
applications fitting 356®, 912®, 914®, 912E®, 911®, 930®, 964®, 993® and Volkwsagen
applications fitting VW Type 1 and VW Type 4.
LN Engineering's Nickies™ cylinder and piston kits are the culmination of every technological advance related to pistons and cylinders for your aircooled Porsche or Volkswagen engine! Nickies™ aircooled cylinders make the difference! Benefits include:
Nickies have more surface area and up to twice the thermal conductivity of factory Mahle cast aluminum cylinders
Nickies have as much as four times the thermal conductivity of cast iron or ductile iron cylinders
Nickies have up to 50% greater tensile and ultimate yield strength than OEM Porsche cast aluminum cylinders
Nickies are stronger and more ductile than any cast iron, ductile iron, or aluminum OEM or aftermarket cylinders
Nickies allow for larger slip-fit and machine-in sizes than previously available with cast iron or aluminum cylinders
Most Nickies cylinders for Porsche applications come half-mooned for improved crankcase windage, which is typically good for 8-10hp over factory Mahle non-half-mooned cylinders
Nickies are SCCA legal
Nickies are 100% Made in the USA
How are Nickies™ different from a factory Porsche (OEM Mahle) cast aluminum Nikasil™ 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 Kolbenshmidt's Alusil™. Although both were aluminum, that's where the similarity with Nickies™ ends. Castings work great for high volume production, but billet construction allows us to use the best material and manufacturing processes to build the ultimate aircooled cylinder.
Why no provisions for sealing rings, head gaskets, or o-rings on Nickies cylinders for Porsche applications where the factory Mahle cylinders had them?
Although some factory Porsche Mahle Nikasil cylinders have provisions for head gaskets, sealing rings, or o-rings, our Nickies cylinder sets do not come with any for several reasons. We've found through failure analysis of original cylinders, 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 sealing, head gasket, or o-ring grooves, we can add them to most cylinders for a small surcharge.
Case Study: What makes Nickies™ the latest step in the evolution of the aircooled VW and Porsche cylinders?
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, extruded for LN Engineering by Hyrdo in the United States, 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:
Increased Strength: Factory cylinders used a high silicon casting alloy that reduces expansion, but Nickies use a low silicon alloy with slightly higher expansion rates which greatly increases the strength and ductility of the cylinder. The material used in the OEM Mahle or Kolbenschmidt cast aluminum cylinders has a tensile yield that varies from 36k to 42k psi. Through our close work with Alcoa (now Hydro) 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 cylinder plating, 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 cast Porsche cylinders. Our alloy is up to 35% stronger than commonly used cast iron alloys, making our cylinders the best available!
Increased Cooling: We achieve nearly double the thermal conductivity with our low silicon extruded aluminum alloy over the factory high silicon casting alloy used in original Porsche cast aluminum cylinders made by Mahle and Kolbenschmidt. The factory cylinders utilized higher silicon levels to limit expansion rates, however this reduces thermal conductivity. Nickies™ cylinders have up to 400% increase in thermal conductivity over cast iron cylinders. Paired with these improvements in material science, most cylinders have increased surface area and fin count, up to an extra 65% more surface area (varies by model and application).
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. Reduction in silicon content both increase strength and ductility.
Increased Durability: LN Engineering has worked with Millennium Technologies for over 20 years, perfecting the NSC plating and honing process for its Nickies™ cylinders. The low-friction and long-wearing nickel silicon carbide electroplating used, coupled with LN Engineering's exclusive honing surface finish standards, provides the longevity and durability expected from factory Nikasil™ plated cylinders, but with bore sizes significantly larger than any slip-fit or machine in Porsche cylinder and piston set offered by Mahle or Mahle Motorsports. Millennium's NSC plating is proven to withstand high sulfur fuels and has cylinder plating adhesion on par with Mahle's Nikasil plating.
How does the plating used on Nickies™ cylinders differ from Mahle's Nikasil™ used on factory Porsche cylinders?
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 for VW and Porsche engines come with a limited lifetime warranty on the plating (warranty offered by Millennium Technologies). No cylinder commercially available comes with that promise!
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™ cylinder plating 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 suitable for use with Nikasil plated bores.
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 for Nikasil 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 profilometer is used to check the roughness average (RA) and the depth (RPK, RVK, and RK) of our honing patterns to ensure proper engine performance.
I've heard of problems with Nikasil™ cylinders and high sulfur fuels in the US. Is this true?
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. LN Engineering carries out a 100% quality check on every Nickies™ cylinder it makes, ensuring the cylinder plating and honing meets its strict standards.
Why have I heard there aren't any good piston 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™ or NSC-plated cylinders. In fact, we have quite an extensive array of Nikasil™ compatible ring sets from Porsche's original equipment manufacturer, Goetze, as well as from NPR, Hastings, and Total Seal. We pair modern, thin, low tension piston rings with our VW and Porsche piston and cylinder sets as they seal better and wear better than the thicker, higher tension rings typically used with cast iron cylinders. Even select low-tension chrome rings can be run on our NSC plating with excellent compatibility.
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!
All VW, Porsche 914, and early Porsche 911 models used 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.
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 compared to cast iron or aluminum Nikasil™ plated cylinders?
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™ cylinders are 35% stronger than the best ductile iron available, debunking the myth that steel sleeves are needed for strength. Nickies™ also make more horsepower since the engine runs cooler and has less friction!
Interesting factoid: LN Engineering once offered biral-type cylinders, dubbed "Biral Babies," (shown above) as an alternative to our Nickies.
What pistons should I use with Nikasil™ plated aluminum cylinders?
Where a Mahle piston best suits a Mahle cylinder due to to use of high-silicon alloys to limit expansion, the proprietary alloy used for our Nickies™ cylinders is designed for optimal piston to cylinder clearance using high-strength 2618 aluminum alloy forgings. We supply pistons sets from JE Pistons, CP-Carrillo, and Mahle Motorsports manufactured out of 2618 for optimal performance with our Nickies™ cylinders. We can also supply custom pistons all VW and Porsche applications at no extra charge to suit your specific needs if we do not offer a shelf piston.
Pistons purchased from LN Engineering are provided with the correct piston to cylinder clearance to ensure quiet operation like factory and OEM piston and cylinder sets. Typical clearance for a 2618 forged piston in our Nickies cylinders is .0015", but can vary depending on bore size and application.
Case Study: How do you solve the problem of thermally overloaded small aircraft engines?
2-Cylinder Half VW Type 1
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. In our initial testing with Nickies, we observed up to a 150 degree F reduction in cylinder head temperatures and up to a 20 degree F reduction in oil temperature on the dyno on a VW Type 1 engine equipped with Nickies.
Increase horsepower: Current heavily modified 1/2 VW platforms peak out around 40 HP using heavy, poor cooling cast iron cylinders, but do 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. A reduction in cylinder temperature reduces intake charge and improves volumetric efficiency and NSC cylinder plating reduces friction, both of which help to make more horsepower through increased efficiency.
Rotax 912: Zipper Big Bore
LN Engineering was contacted by Hal Stockman, an expert in Rotax 912 engines for light aircraft. He discovered limitations in the factory cast aluminum Nikasil cylinders in performance applications and asked us to develop and manufacture for him several big bore piston and cylinder kits for the Rotax 912 engine in 86, 88, and 92mm. Hal's performance cylinder sets for Rotax 912 engines are are sold exclusively by Zipper Big Bore. The Zipper Big Bore kits saves 3 pounds over the factory cast aluminum Nikasil plated cylinders and allows significant increases in horsepower and torque, while allowing use of lower octane fuels. Billet construction also provides added strength and durability over the factory cast cylinders and allows significantly larger bore sizes than previously possible.
Nickies have been trusted in experimental light aircraft for almost 20 years with a proven track record. Why trust your build to anything less?