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Two-stroke engine cylinders have ports to exchange gas. While the engine runs, the piston and its piston rings slide over these ports in the cylinder walls, and the rings may project into the ports. This paper explores this, first, by reporting a simple model of material mechanics that predicts rings might project into ports, and second, our experimental verification. We installed strain gauges on the bottom of the top and second rings, over the intake and exhaust ports, and ran signal wires out of the engine. We then examined the variations of strain while running the engine. Our analysis confirmed how the dimensions and the tension of the rings, and the dimensions of the ports, affect ring projection into ports as static displacements.

We aim to maximize the performance of air-cooled engines (such as motorbike engines and small stationary engines) by increasing cylinder cooling and by maintaining uniform temperature around the cylinder circumference. In typical engine designs, air cools the front of the cylinder better than the rear. In an effort to increase cooling at the rear, this research experiments with tapered fins that contract air flow to the cylinder axis between the fins, and with baffle plates mounted between fins symmetrically with respect to a plane through the axis of the cylinder. In a wind tunnel at air velocities between 20 and 60 km/h, we compared cylinders with conventional fins, cylinders with tapered fins, cylinders with baffle plates between conventional fins, and cylinders with baffle plates between tapered fins.

In most air-cooled engines, aluminum cylinder blocks are lined with cast iron, which enjoys a higher wear resistance than aluminum. Recently, rather than a turned periphery, an increasing number of cast iron liners have employed as-cast periphery with projections, so the liner better adheres to the aluminum cylinder block, and improves heat transfer. This study attempts to maximize heat transfer while minimizing cylinder weight, by comparing four liners: (1) a cast iron liner with higher projections on its periphery, (2) a cast iron liner with lower projections, (3) a cast iron liner with lower projections, and aluminum-silicon coated on its periphery by thermal spraying, and (4) a high-silicon aluminum alloy liner with aluminum-silicon coated by thermal spraying. These four experimental liners were fitted in a die-cast low-silicon aluminum-alloy cylinder block, to investigate their joint and cooling characteristics.

The authors have utilized a modified automobile engine with a transparent glass cylinder, which was driven by an electric motor. The effects of the positions of the piston ring gaps, the end clearance size and the shape of the piston ring gaps on the lubricating oil flow were examined using the modified engine. The results indicate that the main stream of the lubricating oil flow goes from the lower ring gap to the upper ring gap in all of the positions of the piston ring gaps and that the position of the oil ring upper side rail gap has a great influence on the lubricating oil flow.

To reduce fuel consumption without complicated engine valve systems, we attempted to stop some fuel injectors, while operating both intake and exhaust valves normally, under idling, no-load and lighter load conditions. This study stopped one or two injectors in an in-line four-cylinder gasoline engine, and two or three injectors in an in-line six-cylinder gasoline engine, and then investigated the resulting fuel consumption and variation rates of engine speed. We calculated fuel consumption by measuring fuel injection time and engine speed. Results indicate that, in an in-line four-cylinder gasoline engine, deactivating every other fuel injector, in cylinder firing order, making two deactivated injectors, reduced fuel consumption, compared to the usual condition with all fuel injectors activated, under idling, no-load and lighter load conditions.