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Advances in motorized vehicle vibration control have increased consumer expectations to feel minimal vibration when operating vehicles in any environment; on and off road. Small outboard marine engines have a heightened need for vibration isolation, since the user often steers using a tiller arm connected to the outboard. Traditional engine mount systems allow the mount reaction loads to create a periodic torque about the steering axis and result in significant tiller arm shaking forces. This paper presents a novel mount arrangement that minimizes the shaking couple about the steering axis and isolates the tiller from engine vibration. The concept was first modeled using rigid body dynamics software to predict vibration of the tiller arm. Testing confirmed the simulation, and demonstrated a significant reduction of vibration transmitted to the tiller arm and boat seat compared with a traditional focused mount system.

One-dimensional unsteady gas dynamics dominate the prediction and optimization of two-stroke engine performance. Its application in engines with complicated geometry is, however, limited because the flow through the engine is three dimensional in nature. Multidimensional CFD has the capacity to capture the effect of complicated flow fields. However, most existing CFD studies include either only one cylinder with a partial exhaust system or just a separate exhaust manifold, and boundary conditions need to be fed from experimental data. It is found in this study that such simplifications may yield misleading results. In a previous study, the authors extended a multidimensional CFD code, KIVA to simulate a multi-cylinder engine together with a full exhaust manifold. The need for exhaust pressure boundary conditions was thus eliminated. In continuation of this study, a crankcase model was first developed to dynamically predict the crankcase pressure.