Dinan High Performance Heat Exchanger - 2015-2021 BMW M2/M3/M4

Further testing focused on the heat exchanger produced the optimized design you see before you. With 60% more volume and 19% more face area than stock along with being a whopping 40mm thick (stock is 24mm), it becomes quickly apparent how heat soak is averted with the improved setup. While the unit could be physically thicker the 40mm dimension was ultimately chosen with consideration of airflow requirements of the main radiator which is located directly behind the heat exchanger. A thicker core would diminish airflow and sacrifice normal engine cooling which would be potentially detrimental to the long term health of the engine. The increased physical stature of the heat exchanger allows a reduction in water temperatures to the intercooler an average of 9° across the RPM range. The colder water entering the intercooler then improves is efficiency and allows the intake air to be cooled by an additional 6° average across the RPM range compared to the stock unit. The reduction in intake air results in an impressive 10 HP and 20 ft-lb of torque gain without any changes in the engine tune.