do88 BMW S55 M3/M4 (F80/F82/F83) Side Mounted Radiator

The S55 twin-turbo engine powering the M3 and M4 F8X uses a top-mounted water-cooled intercooler system rather than a conventional air-cooled intercooler. This charge cooling circuit runs on its own separate coolant loop, combining two parallel-connected radiators and a pump, the larger one positioned in front of the centre cooling module, and a second, smaller one located in front of the right-side wheel arch. Lowering the water temperature in this circuit translates directly to lower charge air temperatures, making high-performance radiators genuinely important for maintaining low, stable IATs during hard driving.

This side-mounted radiator addresses the smaller wheel-arch unit specifically. do88 extended both the core height and thickness by 28mm, delivering an 18% larger frontal area and a substantial 100% larger core volume over the factory unit. To fit this genuinely larger radiator into the available space, do88 designed a purpose-built carbon fibre air duct, manufactured from prepreg material in an autoclave process for genuine strength and precision. Real-world testing, measured during full-throttle 0-240km/h acceleration runs at an airstrip under identical same-day conditions, confirmed a 5°C reduction in post-intercooler air temperature (34°C versus 39°C stock) with this radiator fitted.

Works with: OEM cooling lines, genuine drop-in installation. Best paired with do88's Front-Mounted Intercooler Radiator (75% larger core, sold separately) for the complete charge cooling upgrade across both parallel radiators.

Why Choose This Radiator

• 100% larger core volume and 18% larger frontal area than the factory unit
• Real-world tested 5°C reduction in post-intercooler air temperature
• Purpose-built prepreg carbon fibre air ducting, autoclave manufactured
• High-efficiency core with 8mm multi-louvered fins and multi-channel core tubes
• Genuine drop-in installation using OEM cooling lines
• Benefits both stock and heavily modified builds, on track, street, or strip

Compatibility

• BMW F80 M3/M3 Competition (2015-2018, S55)
• BMW F82/F83 M4/M4 Competition/GTS/CS (2015-2020, S55)