Characterization of Different Injection Technologies for High Performance Two-Stroke Engines

High performance engines are used in many different powersports applications. In several of these applications 2-stroke engines play an important role. The direct injection technology is a key technology for 2-stroke engines to fulfill both the customers’ request for high power and the environmental requirements concerning emissions and efficiency. As the load spectrum differs from one application to the other, it was interesting to find out if different injection technologies can answer the needs for different applications more efficiently regarding performance but also economic targets. Therefore, the results of the BRP Rotax 600 cm³ E-TEC (direct injection system) engine are compared to the same base engine but adopted with the LPDI (low pressure direct injection) technology developed by IVT at Graz University of Technology. The systems were compared on the engine testbench over 17 rpm / load points representing different product usage profiles. The individual systems were optimized by variation of injection timing, lambda, ignition timing at each point. The focus was primarily on reducing HC emissions during the optimization. These optimized points were then used as the basis for in-cylinder 3D-CFD to better understand the differences of one system compared to another at varying rpm / load points. Finally, the two systems were installed into a motorcycle for further comparisons to establish whether the raw emissions advantages could be realized in a transient WMTC cycle with exhaust aftertreatment. In conclusion, a better understanding of the trade-off between performance levels and emission levels for a high output 2-stroke engine was achieved.