Abstract: A plenum is surrounded by runners that spiral around the plenum sidewall to the entrances to the engine cylinders. The circumferential extent of each runner exceeds 360 degrees about a longitudinal axis of the plenum. Portions of the runners share common wall portions with portions of the plenum.

Abstract: An integrated tuned air induction system for an internal combustion engine comprises an air intake leading to an air filter compartment. The air filter compartment leads to a tube that extends horizontally past a bank of cylinders that is served by the system. The tube leads to a tubular extension piece that creates a 180 degree turn. After this turn, the airflow passes through an air body containing a valve that controls the induction airflow. After the air body, the airflow passes to a plenum zone that lies parallel to the first tube. Spiral runners arranged transversely to the length of the plenum zone communicate the plenum zone to the intake of each cylinder in the bank. The first tube, the runners, and the plenum zone are formed by a single plastic part. The air filter compartment is defined by an end wall of this part and a removable cover. An integral wall of the part serves to mount the part on the engine while providing support for the runners.