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Nowadays, market shares for plastic intake manifolds are still increasing, although the competition with aluminum and magnesium is tough [1], [2]. It is becoming more and more apparent, that for a further spread one of the key issues is the managing of high temperatures generated by EGR inlets. Successful design of such devices will depend heavily on the correct prediction of the temperature loads. 3-D CFD calculations (e.g. with STAR CD or Fluent) turn out to be a valuable tool for this purpose. However, providing realistic boundary conditions remains difficult unless measured engine data for EGR mass flows and temperature is available. The alternative to experimental data is the calculation of boundary conditions with the help of a 1D charge cycle program, e.g. GT Power, which serve then as time dependent, tabulated input for the CFD codes.

Unsteady intake wave dynamics have a first order influence on an engine's performance and fuel economy. There is an abundant literature particularly for naturally aspirated SI engines on the subject of intake manifolds and primary runner lengths aimed to achieve a tuned intake air line. A more demanding design for today's engines is to increase efficiency to meet the requirements of lower fuel consumption and CO2 emissions. Today's tendencies are downsizing the engine to meet these demands. And for drivability purposes, the engine is combined with a turbocharger coupled with a charge air cooler. However, when the engine's displacement is reduced, it will be very dependent on its boosting system. A particularly interesting point to address corresponds to the engine's operation in the low speed range and during transients where the engine has large pumping losses and poor boost pressure. This operation point can be optimized using acoustic supercharging techniques.

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.