Performance of Low-Octane Fuels in a Rotax 914 Engine with Advanced Knock Mitigation Strategies

Abstract

An experimental study was performed to determine the knock limited performance of a Rotax 914 engine while operating on fuels with an anti-knock index (AKI) of 87, 70 and approximately 20 as compared to a baseline operation on low-lead aviation gasoline fuel (100LL). Experimental data were also taken for non-knocking and knock-limited performance on 87 AKI gasoline at 5500 RPM over a range of intake air temperatures and combustion phasing. The benefit of direct injection (DI) of fuel, dual spark plugs, and charge air cooling was investigated and compared to single spark plug port fuel injection under similar conditions.