Koyorad 18.9 psi Hyper Radiator Cap Mazda MX5

The Koyorad Hyper Radiator Cap is designed to maximise the cooling efficiency of Koyorad all-aluminium performance radiators. Manufactured in Japan using high-quality components, this cap increases system pressure to improve coolant performance and heat management in demanding driving conditions. With a pressure rating of 1.3 bar (18.9 psi / 130 kPa), the Hyper Cap raises the boiling point of coolant significantly compared to standard radiator caps. Most modern vehicles use a 0.9 bar cap, whereas the higher pressure rating of the Koyorad Hyper Cap increases the coolant boiling point to approximately 131°C, helping the cooling system absorb and dissipate more heat. This improved thermal capacity allows the engine to maintain stable operating temperatures during high-performance driving, making it an ideal upgrade for vehicles equipped with Koyorad aluminium radiators. All Koyorad radiators are supplied without a radiator cap. This Hyper Radiator Cap is designed to fit all Koyorad radiators equipped with a filler neck (all NA and NB Koyorad radiators). Features 1.3 bar (18.9 psi / 130 kPa) pressure rating Raises coolant boiling point to approximately 131°C Manufactured in Japan using high-quality components Designed specifically for Koyorad aluminium performance radiators Benefits Improves cooling system efficiency Increases coolant heat capacity under high-load conditions Helps maintain stable engine temperatures during performance driving