This paper details the development of a new dynamic Intake Air Simulator (IAS) for use on single-cylinder test engines, where the gas dynamics are controlled to accurately simulate those on a multi-cylinder engine during transient or steady-state operation. The third generation of Intake Air Simulators (IAS3) continues a development of new technology in the Powertrain Control Research Laboratory (PCRL) that replicates the multi-cylinder engine instantaneous intake gas dynamics on the single-cylinder engine, as well as the control of other boundary conditions.This is accomplished by exactly replicating the intake runner geometry between the plenum and the engine intake valve, and dynamically controlling the instantaneous plenum pressure feeding that runner, to replicate the instantaneous multi-cylinder engine intake flow. The plenum pressure is controlled in this technology by means of six rotary valves, seven proportional valves, and the throttle valve system from the representative multi-cylinder engine. The proportional valves control the magnitude of flow through the rotary valves, and the rotary valves control the instantaneous wave form of the flow out of the plenum by means of their rotational speed. This flow out represents the net instantaneous flow out of the plenum that would otherwise go to the other cylinders in the multi-cylinder engine.The single-cylinder engine using this technology will have the same gas dynamics as if it were in a multi-cylinder engine, and the results of studies in charge motion, mixing, combustion, and even engine performance will be much more representative of what would be expected on the multi-cylinder engine.