CSF High-Performance Auxiliary Radiator for BMW G8X M3, M4 & M2 (S58)

Is your S58-powered BMW entering limp mode during track sessions? High coolant temperatures are a known issue for the G8X M3, M4, and M2 when pushed hard, especially as power levels climb toward the 1000 horsepower mark. The CSF 8321 replaces the factory plastic-tank auxiliary units with a high-capacity, all-aluminum design that prolongs the heat soak threshold and keeps you on track longer.

The CSF 8321 features a 2-row 42mm core utilizing exclusive B-Tube technology, which increases the heat transfer surface area compared to standard oval tubes. This is paired with ultra-efficient 5mm tall multi-louvered fins to maximize heat dissipation without sacrificing airflow to the rest of the cooling stack. Unlike the OEM units that use plastic pods, CSF uses TIG-welded aluminum tanks and reinforced mounting brackets for superior durability under racing conditions.

Key Features

• 2-Row 42mm high-performance core with B-Tube technology
• Ultra-efficient 5mm tall multi-louvered fins
• 100% all-aluminum TIG-welded construction
• Integrated detachable rock guards to prevent core punctures
• Multi-fit design works for both left and right side locations
• OEM-style quick-connect inlet and outlet for a drop-in fit
• Satin black finish for a stealthy OEM+ appearance
• Individually leak and pressure tested
• 2-year limited warranty

Specifications

Fits

Fits the BMW G8X chassis, including the G80 M3, G82/G83 M4, and G87 M2. These vehicles use two auxiliary radiators. Units are sold individually, so order quantity two for a complete vehicle refresh.

Installation

This is a true drop-in fit application that installs in the OEM location using factory mounting hardware and quick-connect hoses. No modifications are required. CSF recommends following the manufacturer repair manual or using a qualified installation facility if you are not confident in performing the swap.

Warranty: 2-year limited warranty.