Many modern engines incorporate swirl flaps into their intake manifolds. These allow for the electronic control of airflow. By controlling the airflow with the flaps there is a greater ability to regulate the fuel-to-air ratio. This aids in emissions and improves low-end torque.  Over time these swirl flaps which are just a butterfly valve can … Continue reading Say Goodbye to Plastic: Upgrading OM642 Swirl Rods