do88 BMW B58 Gen 2 (M240I/M340I/M440I/Supra) Front Mount Heat Exchanger

The B58 shares real similarities with the S55 engine found in the F80/F82 M3/M4, both use a water-to-air charge cooler paired with a front-positioned heat exchanger (water radiator). This radiator cools the water flowing through the charge air cooler, and that water in turn dissipates heat from the charge air before it enters the engine. The factory charge air cooling system on the B58 is prone to genuinely rapid heat soak under demanding conditions, and high intake air temperatures force the ECU to pull timing or reduce power, leaving enthusiasts with inconsistent results exactly when they don't want them.

do88's replacement directly solves this with a premium unit delivering 80% more core volume than stock, using a dual-row, 48mm thick design that boosts cooling surface area by 36%. A quad-pass layout maximises coolant exposure to the core, while a larger 5mm fin height balances the increased cooling capacity with good airflow to the engine radiator positioned behind it. Total fluid capacity increases by 2.6 litres for genuine thermal buffer under sustained hard use. Installation integrates with OE components including the transmission cooler mounting points and both OE rock guards, keeping things as close to factory as possible elsewhere in the install.

Important: some trimming of the OE plastic radiator mounting frame is necessary to fit this larger unit (see installation instructions). This is not a pure bolt-on, budget time and basic tools for this step.

Fitment note: for the G20/G21 330i and G22/G23/G26 430i (B48/B46 engine), this radiator is only suitable for cars fitted with a water-cooled intercooler.

Why Choose This Front Mount Heat Exchanger

• 80% larger core volume than the factory unit
• Dual-row, 48mm thick core, 36% more cooling surface area
• Quad-pass layout maximises coolant exposure to the core
• 2.6 litre increase in total fluid capacity for genuine thermal buffer
• Integrates with OE transmission cooler mounts and both OE rock guards
• Directly addresses the B58's documented heat soak and limp mode risk under demanding driving

Compatibility

• Toyota GR Supra MK5 (A90/A91, 2020+, B58/B48)
• BMW G42 M240i/M240iX (B58)
• BMW G20/G21 M340i/M340iX (B58)
• BMW G20/G21 330i/330iX (B48/B46) - water-cooled intercooler only
• BMW G22/G23/G26 M440i/M440iX (B58)
• BMW G22/G23/G26 430i/430iX (B48/B46) - water-cooled intercooler only
• BMW G29 Z4 20i/30i/M40i (B48/B46/B58) - water-cooled intercooler only for 20i/30i

Installation note: requires trimming of the OE plastic radiator mounting frame. See installation instructions for details.