Single Cycle Scavenge Testing a Multi-Cylinder, Externally Scavenged, Two-Stroke Engine with a Log Intake Manifold

The gas exchange process of the two-stroke engine is such that the flow of fresh air into the cylinder and exhaust gas out of the cylinder occur substantially together. It is therefore the case that not all of the air delivered will be trapped during this scavenge process. Extensive research has already been conducted into optimising the porting layouts of two-stroke engine cylinders. One of the techniques developed at The Queen's University of Belfast for evaluating scavenging is a unique experimental method described as the ‘single cycle scavenge test’. Although the test does not reflect the actual scavenge process in a firing engine, it is a sufficiently useful procedure to have become an industrial standard for scavenge evaluation. This paper discusses the application of that test procedure in the development of a multicylinder, externally scavenged, two-stroke automotive engine.