A vehicle engine operates most time at transient modes. Therefore the problem of engine noise investigation in real-life operation conditions is important. The paper presents a method and results of calculation of the engine structure-borne noise at transient operation mode using the components of the IC Engines Single Informational Environment. Investigation of the noise of the V8 120/120 mm diesel engine at the acceleration mode was carried out. The transient mode was presented as an ensemble of steady modes for which the working cycle was calculated and noise calculation was carried out successively. Finally the engine acceleration performance was formed. Analysis of the investigation results demonstrated that at the acceleration mode, the diesel engine noise was by 1.5-2.0 dBA higher than at the similar engine speeds at stationary conditions. It was determined that the basic factors which cause the difference in the diesel engine acoustic performances at the acceleration mode were the injection start angle, ignition delay period, thermal inertia of engine parts and some others. Consequently the pressure rise rate in the cylinder increases which causes the engine noise growth.