Technical Paper
Indicated Cycle Efficiency Improvements of a 4-Stroke, High Compression Ratio, S.I., Opposed-Piston, Sleeve-Valve Engine Using Highly Delayed Spark Timing for Knock Mitigation
2012-04-16
2012-01-0378
A fixed-geometry configuration of Pinnacle Engines' 4-stroke spark-ignited 250cc single-cylinder opposed-piston reciprocating sleeve-valve engine is presented. A test cell has been developed with a custom crank-angle based data acquisition system to allow friction testing and indicated cycle development. Incipient knock criteria are defined and test results are presented to compare the opposed-piston's indicated cycle performance to conventional single-cylinder engines. At high loads, the Pinnacle opposed-piston engine utilizes the Cleeves cycle, an operating mode in which spark timing is highly delayed from best power spark advance, to enable knock-free operation at an elevated 15:1 compression ratio using 87 octane fuel. Data is presented for sleeve-valve operating temperatures, peak cylinder pressure effects, and exhaust gas temperatures.
