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At the runner outlets of an air intake manifold for an internal combustion engine, the firing order of the engine and the valve timing are leading to a transient pressure excitation. The resulting pressure waves in the air intake system (inlet manifold and upstream line including air cleaner) have a significant effect on volumetric efficiency. A natural air overcharge - called ram effect - is caused at specific engine rpm that corresponds to a perfect timing between the intake valve closing and the maximum pressure at the intake valve. This paper presents a new measuring method, used to characterize the dynamic behavior of the air intake system, and to forecast the impact of some of their parameters on volumetric efficiency. A mathematical model of the air intake system was built which is based on the electrical analogy and which uses the well-known results of the resonance RLC circuits.