In consideration of the fact that in extreme Enduro competitions two-stroke motorcycles are still dominating, the Institute of Internal Combustion Engines and Thermodynamics, Graz University of Technology, with a long tradition in two-stroke technology, has developed a new 300 cm3 two-stroke motorcycle engine.
The 2-stroke LPDI (Low Pressure Direct Injection) technology was originally developed for the 50 cm3 Scooter and moped market in Europe. In 50 cm3 applications the LPDI technology fulfils the EURO 4 emission standard (2017) [1]. In a next step the LPDI technology was applied to a 250 cm3 Enduro engine demonstrator vehicle. Based on the results of the demonstrator, a complete new high performance 300 cm3 engine was developed. The development of this new engine will be described in this publication.
Some interesting aspects of the layout with 3D-CFD methods and also 1D-CFD simulation to optimize the exhaust system by DoE methods are discussed in the paper.
For the first prototype (prototype 1) some carry over parts had to be used - crankshaft, connecting rod, clutch, gearbox - whereby these parts were redesigned for the next project step (prototype 2) in order to optimize the engine weight. The design of the engine will focus on special features like the balance shaft and the optimization steps between prototype 1 and prototype 2. Some improvements identified during the prototype 1 durability test will also be described.
The most interesting aspect of the engine test bench development is the performance development which is strongly linked to the 1D-CFD simulation.
Finally, the engine calibration and EMS (engine management system) will be described in this paper. In this case, the span between idle and maximum power as well as the transient calibration were the challenge during the development. Quick and smooth response on throttle opening is essential for the characteristic of these engines.