Proper design of an engine's intake and exhaust system can offer the benefits of torque increase, fuel economy, and emission control. A new concept of intake airflow dynamics is presented, with a multiport model of an intake tube. Fluid transmission line dynamics are applied to a distributed parameter model of straight-tube manifold. This application proved itself to be an excellent way of analyzing the intake system predicting intake pressure waves of an internal combustion engine. With this modeling, transient and frequency responses are obtained to setup a design basis for the intake manifold.