An air-to-air charge air cooler for cooling air supplied to an internal combustion engine includes a tube assembly including a plurality of tubes extending in a longitudinal direction. The plurality of tubes is arranged adjacent to one another. Each of the plurality of tubes includes an inlet to receive airflow and an outlet to output airflow. A turbulator is arranged in at least one of the plurality of tubes, the turbulator having a pitch defined in a direction transverse to airflow through the tube. The pitch varies in at least one of a longitudinal direction and a transverse direction of the tube.