The paper presents a detailed study of a unique lubricating oil transport and exchange path that is important for friction, wear, and oil consumption in a 4 stroke spark ignition engine, namely the oil flow from the piston to the cylinder liner. The study consisted of experiments with a test engine utilizing 2D LIF (Two Dimensional Laser Induced Fluorescence) techniques to view real time oil transport and exchange, along with computer modeling. The effects of engine speed, load, and oil ring design were included as part of the research. The test conditions ranged from 800 RPM to 4500 RPM, while the load was varied from closed throttle to wide open throttle. Several different oil control ring designs were utilized, including U-Flex, Twin-Land, and 3-Piece.
Oil transport and exchange from the piston to the liner was observed under several different engine conditions, typically moderate to high engine speeds and low loads. Such transport and exchange was observed to occur toward the end of the piston's stroke, near both BDC and TDC. For each location, the oil transport and exchange was examined in two main regions, inside the third land and inside the oil control ring groove.