Forge Motorsport Top Mount Replacement Chargecooler and Expansion Tank for BMW MSport S55 Engine
Upgrade your BMW MSport S55 Engine with the Forge Motorsport Top Mount Replacement Chargecooler and Expansion Tank. This innovative chargecooler is designed and manufactured at Forge Motorsport HQ in Gloucestershire, England, using high precision laser cut sheet metal panels and TIG welding for maximum strength and durability.
The all-aluminium construction of the chargecooler eliminates common issues such as plastic end tank splitting, failure at high boost, and leaks between the core and end tanks. The bar and plate core design, evaluated through Solidworks CAD design and CFD analysis, outperforms other alternatives on the market. With a quadruple pass design, the water flows through four passes of the cooler, resulting in improved cooling efficiency.
Unlike the OEM system, the Forge BMW M3/M4 S55 Chargecooler system uses an expansion tank instead of a header tank. This unique design includes a filler cap located at the highest point on the Chargecooler, ensuring that the charge is 100% full of coolant with no air pockets. This maximizes the efficiency of heat rejection within the Chargecooler water jacket.
The Forge Motorsport Top Mount Replacement Chargecooler and Expansion Tank offers over 71% increase in volume and over 42% increase in frontal area. In hot climate testing, constant dyno runs showed significantly lower inlet temperatures compared to the stock system, resulting in an increase in power of up to 20BHP.
As part of Forge Motorsport’s strict quality control process, each chargecooler unit is carefully inspected and pressure tested before dispatch. The expansion tank also features a 1/8 NPT port ready for water/methanol injection if required.
The installation of this chargecooler and expansion tank does not require any trimming or cutting of the vehicle, and all parts can be returned to standard if necessary. Fitting of the part is available at our performance workshop at Progressive Parts.





