Koyorad Racing Aluminium Radiator | Subaru WRX & STI (2005|2019)

The Koyorad Racing Aluminium Radiator is a direct-fit upgrade for your Subaru WRX or STI, built to keep the boxer engine cool through spirited driving, track days and gravel-road punishment alike. Hand-TIG-welded in Japan from all-aluminium, it drops straight into the factory mounting points for a clean, no-fuss install and a serious step up in cooling performance.

Boxer Engines Run Hot When You Push Them

Subaru's turbocharged boxer engines are built for punishment, but the factory plastic-tank radiator wasn't designed for repeated track sessions, tarmac rallying or aftermarket boost. Heat soak creeps in fast once you start pushing it.

A Cooling System Built for Real Punishment

Koyo's 36mm core features optimised fin density and tube design to move more heat out of the system, backed by a full-aluminium, TIG-welded build that shrugs off the vibration and heat-cycling that kills OEM plastic tanks over time. Every unit is pressure-tested before it leaves the factory.

Cooler Coolant, More Confidence on Track

With stable coolant temps locked in, you get consistent power lap after lap, less risk of overheating on hot laps or gravel stages, and a radiator tough enough to handle whatever's next for your WRX or STI | more boost, more track days, more seat time.

Key Features

• All-aluminium construction with TIG-welded tanks for maximum durability
• 36mm core for increased cooling capacity over the factory unit
• Optimised fin density and tube design for efficient heat transfer
• Direct-fit design | uses factory mounting points and fan shroud, no modifications required
• Compatible with standard radiator caps and coolant hoses (unless otherwise specified)
• Pressure-tested for reliability under sustained high load and temperature
• Ideal foundation for further performance upgrades, including higher boost levels and track use
• Made in Japan

Specifications