A combustion characteristic of the pseudo-biomass gas which had composition calculated in the simulator, DYSEBIC, was investigated by an engine experiment. LPG engine with four cylinders was applied, and an in-cylinder pressure sensor and a crank angle sensor were installed. As a result of experiment, it was confirmed that data mining of in-cylinder pressure signals could lead calorific value of pseudo-biomass gas. Besides, it was suggested that management of heat conversion efficiency could use a result of engine combustion.