Engine air induction system

An air induction system for use in an internal combustion engine comprising:

• a throttle body having an airflow surface defining a main airflow bore and a throttle plate mounted in the bore;
• an intake manifold housing mounted to the throttle body, downstream of the throttle body, with the housing including an air flow surface defining a main airflow passage aligned with the throttle body main bore and is oriented such that air generally flows in a direction other than vertical, an incoming flow passage intersecting the main airflow passage, and a plurality of intake runners having intake passages intersecting the main airflow passage;
• and
• a plurality of annular grooves in the intake manifold housing along the surface of the main airflow passage, located downstream of the throttle plate and upstream of the incoming flow passage, for causing turbulence in the main air flow passage and trapping moisture and contaminates that may backflow toward the throttle plate.

A method of improving the performance of an air induction system, having a throttle body, with a throttle plate, mounted to an intake manifold housing which includes a main airflow passage, through which air flows, and an incoming flow passage, for use in an internal combustion engine, the method comprising the steps of:

• flowing air through the throttle body and the airflow passage in the housing;
• creating turbulence in the air flow between the throttle plate and the incoming flow passage;
• and
• trapping backflowing contaminants between the throttle plate and the incoming flow passage.