Piston skirts

Ford Kent, which evaluates cold ring sticking, piston skirt varnish, oil thickening and consumption. 

The WTD is a cumulative rating based on observation of deposits in the groove and land areas of the piston and lacquer on piston skirts which have been weighted and calculated in accordance with the test procedure. The evalated lubricating oils also contained, where required, conventional viscosity improver, a metal detergent and ZDDP in mineral base oil. The WTD ratings were as follows ... 

The Amoco Chemical Company has successfully raced a car with a plastic engine. Many of the engine parts, including piston skirts, connecting rods, and valve-train components, are made of a polymer called Torlon ... 

Glass-filled polyether either ketone (PEEK) resins are used in the inlet manifold of a Rover racing engine, while polyether sulfone (Victrex) has been used for piston skirts. Fluoroplastics have found many applications in the sealing rings and bearings of automotive drives. 

Plastic piston skirts have long been a development topic the first succesful example was the use (in diesel engines) of inserts in carbon fibre reinforced, internally lubricated PES by Floquet Monopole in France. Two of these in each skirt have the effect of reducing the piston-to-cylinder clearance, with consequent reductions in noise, fuel consumption and pollution, and improved performance (see Fig. 6.20). 

Piston skirt in carbon fibre reinforced PES, by Floquet Monopole (courtesy ICI). 

Fig. 8.5 Schematic diagram describing piston-to-cylinder wall and piston skirt-to-cylinder wall lubrication regime changes during an engine revolution (Courtesy of Texaco Inc.)...

Numerical analyses for the piston and the ring pack are generally discrete models. Predictive analyses for the dynamics and lubrication of sliding interface between the piston skirt and the cylinder wall have been proposed by a number of research groups, for example [8, 11-13]. The primary outputs are piston secondary motion, tilting and lateral translation within the bore, and friction. Attempts have also been made to predict piston slap, as a precursor of piston derived noise [14]. 

Surface texture of the piston skirt, to a lesser extent. 

Zhu, D., Cheng, H. S., Aral, T., and Hamai, K., 1992, A Numerical Analysis for Piston Skirt in Mixed Lubrication - Part I Basic Modeling , ASME Journal of Tribology. Vol. 114 553-562. 

Dr R Castle (Infineum U.K. Ltd, Abingdon, Oxon, UK). What proportion of piston assembly power loss comes from piston skirt/Iiner contact ... 

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