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In this work a two-wheeler two-stroke spark ignition engine was modified to work in the air assisted direct injection (AADI) mode with gasoline as the fuel. Standard mechanical hardware was used. The controller for this system was developed in-house using a FPGA based system-using Labview software. The system controlled the fuel injection, mixture injection, lubricant pump frequency and the spark timing. Preliminary experiments were conducted at 3000 rpm to determine the influencing variables and potential of this system. Mixture injection timing was an important variable. The AADI system reduced short-circuiting of the fuel and the maximum brake thermal efficiency went up from about 21% with the carbureted version to 26%. There was a significant drop in HC levels from about 1500 ppm to 400 ppm with the AADI mode. NO levels went up slightly due to improved combustion.

In this work, a 7.45 cc capacity glow plug based two-stroke engine for mini aircraft applications was evaluated for its performance, emissions and combustion. It uses a fuel containing 65% methanol, 25% castor oil and 10% nitromethane by volume. Since test rigs are not readily available for such small engines, a reaction type test bed with low friction linear and rolling element bearings was developed and used successfully. The propeller of the engine acted as the load and also the flywheel. Pressure time diagrams were recorded using a small piezoelectric pressure transducer. Tests were conducted at two different throttle positions and at various equivalence ratios. The brake thermal efficiency was generally in the range of 4 to 17.5% depending on the equivalence ratio and throttle position. IMEP was between 2 and 4 bar. It was found that only a part of the castor oil that was supplied participated in the combustion process.

Conventional two-stroke spark-ignition (SI) engines have difficulty meeting the ignition requirements of lean fuel-air mixtures and high compression ratios, due to their breaker-operated, magneto-coil ignition systems. In the present work, a breakerless, high-energy electronic ignition system was developed and tested with and without a platinum-tipped-electrode spark plug. The high-energy ignition system showed an improved lean-burn capability at high compression ratios relative to the conventional ignition system. At a high compression ratio of 9:1 with lean fuel-air mixtures, the maximum percentage improvement in the brake thermal efficiency was about 16.5% at 2.7 kW and 3000 rpm. Cylinder peak pressures were higher, ignition delay was lower, and combustion duration was shorter at both normal and high compression ratios. Combustion stability as measured by the coefficient of variation in peak cylinder pressure was also considerably improved with the high-energy ignition system.