To observe the effect of engine applications on small engine design, bending and torsional stresses of a crankshaft were measured dynamically under various load conditions. A dynamometer and a generator were selected as the load sources, because these two devices can provide different load patterns respectively. As the results, the peak bending stresses at the crankshaft pin fillets of a dynamometer set engine were about 40∼60% larger than those of a generator set engine. Conversely, the peak torsional stress at a crankshaft journal of the dynamometer set engine was about 25% smaller than that of the generator set engine. To investigate the reasons of these differences. additional measurements and FEM calculations were carried out. Finally we found that the stiffness of the crankshaft support had a great influence on the value of the peak bending stress and the torsional stress was affected by the installation angle between the engine TDC and the rotor of the generator.