NIKASIL is a trademark name for a process called “electrodeposited lipopholic nickel silicon carbide coating” for various engine components. The coating is mainly applied to piston engine cylinder liners of the engine block. It was introduced by the engine component company 'Mahle' in 1967. The Nikasil process was first developed to allow Wankel rotary engines and Mercedes C11seals to work directly against the aluminium housings. The coating has wonderful characteristics, allowing aluminum cylinders and pistons made from various similar alloys to work directly against each other. Nikasil allowed very large cylinder bores with tight tolerances and thus allowed existing engine designs to be expanded easily, the aluminium cylinder sand castings also gave a much better heat conductivity, lowered friction levels present in cast iron cylinders sleeve liners which are prone to overheating, which is an important factor for a high output engines and with specific attention given to V8 engines.
The Nikasil coating was further developed as a replacement for hard-chrome plated cylinder bores for Mecury Marine Racing, Kohler Engines, and as a repair replacement for factory chromed motor-X motorcycles such as KTM, various snowmobiles, watercraft and many automotive V8 liners and cylinder block bores.
Porsche first started using this on the 1970 in a 917 race car, and later on the 1973 911 RS. Porsche also used it on its line up of standard production cars. Nikasil cylinders were always used for the 911 Turbo and RS models. Nikasil coated aluminum cylinders allowed Porsche to build air cooled engines due to the low frictional qualities that Nikasil coating offered, which had the highest output of any engine of their times.
Nikasil was very popular in the 1990s. It was used by companies such as Audi, BMW, Ferrari, Jaguar, KTM and Motto Guzzi motorcycles in their new engines. However, the sulphur found in much of the world's low quality gasoline caused many Nikasil cylinder sleeves to break down over time causing piston cylinder bore failure resulting in low compression due to damaged cylinder walls which in turn damaged pistons and rings. These fuels are such as that are used in parts of the USA, Brazil many African countries and parts of the UK. The sulfur Nikasil reaction causes damage to the very top of the cylinder bore, where there is the most pressure and contact of the burning mixture and the cylinder lining of Nikasil plating. This ‘leak down’ will cause engines such as the BMW M60 with worn or damaged linings to exhibit a rough idle and left unchecked, the engine will not start.
The only permanent remedy for this problem is the replacement of the entire engines cylinder block. Problems are still present in these engines so affected and cars of this period should be bought with caution unless the service history verifies that work was carried out to rectify the problem. The BMW M52 used iron sleeves from the beginning, and so was unaffected by this problem.
The composition of the engine can be found by checking the engines, engine code and number stamped onto various engine blocks of the BMW M60B30 and M60B40. The only permanent fix for the Nikasil problem is the replacement of the short block with the equivalent block using Alusil linings together with the correct rings, which do not exibit this corrosion problem prevalent with Nikasil bores. Alusil has become a far better option than Nikasil plated linings.
Alusil is an aluminium alloy commonly used to make linerless aluminium alloy engine blocks. Alusil, when etched, will expose a very hard silicon precipitate. The silicon surface is porous enough to hold oil. BMW switched from Nikasil-coated cylinder walls to Alusil in 1996 to eliminate the corrosion problems caused through the use of petrol / gasoline containing sulfur. Alusil engine block sleeves are not an electro-plated process and therefore do not crack, peel or become pitted.
ALUSIL is a treatment of the aluminium surface by either chemical etching or honing and lapping to expose silicon particles on the aluminum surface to act as a wear layer and has been found to be an excellent wear surface through time trials and wear indications of the cylinder bores.
BMW engines using Alusil cylinder block sleeves are as follows: N52, M60 V8, M62 V8, N62 V8 and V12 motors.These aluminum alloy engines weigh in at only 146 kg.
Piston rings from the Nikasil engine may NOT be installed in the Alusil engine and visa versa. This ring change over affects the BMW M60 and M62 engines.
For more information CLICK HERE “BMW V8 Engine Specialists / Motor Spares ” or Call Centre : 0861 7777 22