Download or read book SAE 1999 08 0320 Measurement devices for piston assembly friction and oil film thickness JSAE Technical Paper No 9935347 written by Sungwoo Cho and published by . This book was released on 1999 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A technique for estimating the instantaneous frictional force between the piston assembly and the cylinder wall has been developed by improving the moveable bore technique. The technique can be easily applied to small multi-cylinder engines. The technique was applied to a four-cylinder SI engine under various engine speeds, engine loads and oil viscosity. An instrument for measuring the oil film thickness on the piston rings was also developed by using the commercially available gap sensors. It was possible to measure the oil film thickness on thin oil ring rails as well as on the compression rings. The frictional characteristics were established as a relationship between frictional mean effective pressure and a parameter which is the product of the piston mean speed and the oil viscosity.