Estimation of the Cylinder Pressure in a SI Engine Using the Variation of Crankshaft Speed

This paper describes to measure the cylinder pressure in a SI engine using the variation of crankshaft speed. Assuming engine dynamics as a single degree of freedom the energy equation is derived. Through some assumptions each cylinder pressure can be estimated form the pressure torque.

Through this study cylinder pressures by this method show good accord with measured value in low to medium speed ranges. For more accurate analysis the crank angle based modeling of friction and vibration is required.