CSF Radiator - E82 1M / 135i / 335i

With over 5 decades of radiator manufacturing experience, CSF built this High-Performance All-Aluminum Radiator to keep your 1M, 135i, or 335i running at its best — whether on the street or the track. High horsepower builds and race vehicles both demand cooling performance beyond what factory systems can deliver, and this radiator is designed to meet that need. At the core of the design is CSF's exclusive B-Tube Technology. Unlike standard oval "O" type radiator tubes, CSF's specially engineered "B" shaped tubes are formed and seam-brazed, allowing for thinner, lighter aluminum without sacrificing strength — the B-tube design is actually stronger than welded O-tubes. The seam-brazed, center-inlet construction increases heat transfer surface area by ~15% over regular tubes, effectively delivering the efficiency of two smaller tubes in the space of one — creating dual liquid laminar flow. CSF pairs this with ultra-efficient, precisely aligned multi-louvered fins, with fin specs calculated and wind-tunnel tested for each application to maximize heat rejection. It's a true drop-in fit — no modifications required. OE-style brackets are CNC machined and welded for durability, and inlet/outlet connections match OE specs so you can reuse factory or aftermarket hoses. Features 2-row, 42mm dual core featuring CSF's exclusive B-Tube Technology Ultra-efficient fin design — 6.5mm fin height, multi-louvered for maximum surface area contact CNC-machined "Quick-Connect" inlet/outlet connections CNC-machined brackets and fittings for superior fit and durability All-aluminum race-style drain plug Smooth satin finish Drop-in fit, no modifications — accepts all OEM components including Quick-Connect hoses, A/C condenser, mounting brackets, and fan shroud Fitment Year Range Make Chassis Model Trim Engine 2011 BMW E82/E88 1 Series M - Turbocharged 3.0L L6 (Manual) 2008–2013 BMW E82/E88 135i - Turbocharged 3.0L L6 (Manual) 2013 BMW E82/E88 135is - Turbocharged 3.0L L6 (Manual) 2007–2013 BMW E9X 335i - Turbocharged 3.0L L6 (Manual) 2012–2016 BMW E89 Z4 sDrive28i Turbocharged 2.0L L4 (Manual) 2009–2016 BMW E89 Z4 sDrive35i Turbocharged 3.0L L6 (Manual)