This paper explains and evaluates an indicator diagram generation system for a single cylinder, internal combustion, research engine. The apparatus is digital and consists of a piezo-electric pressure transducer with charge amplifier, a shaft encoder, a digital oscilloscope, and a computer with printer. Motoring data provides valuable information on the performance of the system which is used in the computer software to produce results accurate to 5.4 percent. Results include the indicator diagram itself, the work produced, the horsepower, and the indicated mean effective pressure. Included are an overview of indicator diagram theory, discussion of the apparatus, evaluation of the motoring data, and a thorough explanation of the computer software. Sample results taken while varying the spark advance of the engine compare well with those expected. Actual results are compared with those of the air standard Otto cycle, with the work of the actual cycle being 23 percent lower than that of the air standard. The paper also includes complete instructions for operating the apparatus, providing directions for setting up and running the indicator diagram generation equipment and instructions for running the engine in spark ignition mode. Suggestions are made for further work so that the results may be compared to the fuel- air cycle.

Library of Congress Subject Headings

Internal combustion engines--Indicators--Data processing

Publication Date


Document Type


Department, Program, or Center

Mechanical Engineering (KGCOE)


Ellison, Robert


Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works. Physical copy available through RIT's The Wallace Library at: TJ787.F32 1987


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