Koyo Performance Radiator – Mazda RX-7 FB S3 1983–1985
Application: Mazda RX-7 | FB (2D Coupe) | S3 1983–1985 incl. GSL-SE | Manual Transmission (AT requires external transmission cooler)
Part Number: HH063146 / KH063144
The FB RX-7 is a classic — lightweight, rotary-powered, and endlessly tuneable. But decades of engineering progress mean the factory cooling system is one area where a modern upgrade makes an immediate difference. Koyorad's HH Series 48mm radiator was built to address exactly that, featuring an ultra-high fin density core that maximises heat transfer in the FB's compact engine bay.
Unlike generic replacements, this radiator is precision-engineered as a direct-fit performance upgrade for the stock OE plastic/aluminium unit — no modifications, no fabrication, just bolt it in and drive. Koyorad has also integrated an M12 × 1.25 provision on the top tank centre for a low coolant sensor, and the design is compatible with aftermarket temperature gauge sensors via the included accessory fitting.
Built in Koyorad's privately owned Japanese factories, every unit is hand assembled, Nocolok brazed, and TIG welded by hand using the finest aluminium available. Quality is never sacrificed for quantity.
Why Koyorad?
-
Precise Tube & Fin Alignment — Strict quality control ensures optimal coolant flow and maximum heat transfer efficiency across the entire core.
-
Nocolok Furnace Brazing — All tubes, fins, headers, and brackets are bonded in a state-of-the-art Nocolok furnace, creating a structure that resists vibration, road debris, and the elements.
-
Billet Filler Neck — Precision-machined billet filler necks are fitted to every unit for superior strength, durability, and a reliable seal.
-
OE-Specific Mounting — Application-specific mounting points for fan shrouds, inlet/outlet hoses, and top/bottom pins ensure a pain-free, no-modification install.
-
Hand-Crafted Heliarc Welds — Each radiator is individually Heliarc welded by hand, creating the strongest possible aluminium-to-aluminium bond across all components.
