SAWANT, P. A. U. R. A. S. (2018). ANALYSIS OF INDIVIDUAL, COMBINED AND 2-STEP VARIATION IN INDUCTION SYSTEM OF AN IC ENGINE TO OPTIMIZE PERFORMANCE AND FUEL EFFICIENCY. Unc Charlotte Electronic Theses And Dissertations.
Naturally aspirated internal combustion (IC) engines with conventional intake assembly are tuned only over a narrow speed range to produce an induction boost by capitalizing the pressure waves arising in the intake manifold. In this research, intake runner length, intake valve timing, and intake valve lift, being key contributors to the wave and in-cylinder gas dynamics, are varied individually and simultaneously over a range of values to capitalize the induction pressure waves to boost the engine volumetric efficiency and thus the overall performance and fuel efficiency at all operating speeds. The engine studied is a single-cylinder, four-stroke, spark-ignited, 510 cc, gasoline engine. The 1-D model of the stock engine built in Ricardo Wave software is validated with 98 % accuracy against experimental test results to simulate engine’s stock performance at wide open throttle (WOT). Infinite variations in individual parameters can optimize engine performance but are not feasible due to assembly and space constraints. Simultaneous variations of parameters reduce the number and the span of variations required to optimize engine performance. To further simplify the assembly, two values of each of the above-mentioned parameters giving optimal performance are chosen. As a result, 5.96 percent increment in engine performance is encountered but at the cost of 0.24 percent rise in brake specific fuel consumption (BSFC). To reduce BSFC, the air-fuel ratio is varied as per the load and speed requirements to match stock engine performance. Running the engine on comparatively leaner air-fuel mixtures reduces BSFC by an average of 3.9 percent as compared to stock engine fuel efficiency.