AIRTEC Motorsport Chargecooler Radiator for BMW B48 & B58 Platform - ATRADBMW2AIRTEC Motorsports solution to improving the original set up with the limited space available behind the bumper to make it any wider or taller was to instead extend it forwards by introducing a core thats nearly 60mm thicker, at 90mm in depth. This allowed the use of a triple pass core design to allow the coolant to pass through the radiator three times before it exits, with capacity increased to a huge 23. 3 litres, compared to the original 7. 7