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The V-Cycle is a well accepted and commonly implemented process model for systems engineering. The concept phase is represented by the upper-left portion of the V, in which very high level system simulations are the predominant modeling activity. Traveling down the V toward the vertex, sub-system level and component level simulations are employed as one enters the development phase. Finally, the test and validation phase is completed, and is represented by the right side of the V. Simulation tools have historically been used throughout some phases of the V-cycle, and with the ever increasing computing power, and the increasingly accurate and predictive simulation tools available to the engineer, today it is common that simulation is used in every phase of the cycle, from concept straight through the test and validation phases.

This paper presents the results of an investigation into the comparison between measured and simulated intake system dynamics of the General Motors Quad 4 engine. Simulations of the engine were conducted at eleven wide-open-throttle operating conditions ranging in engine speed from 2500 rpm to 6000 rpm under both firing and motoring operation. Comparisons of basic engine performance (torque, volumetric efficiency, BSFC), as well as dynamic pressure at two locations within the intake manifold (runner and plenum) showed good correlation between measurements and simulation. The total sound pressure level radiated from the intake orifice was also calculated and compared to measured data. The results of this study show that the simulation program has the ability to accurately capture the major features of engine intake system wave dynamics, including amplitude, phasing, and excitation of system resonances throughout the engine operating range.