Mishimoto MX-5 NA/NB Racing Thermostat

When you push your MX-5 hard on the track or add a turbo or supercharger, managing your engine’s thermal baseline becomes critical. The factory Mazda thermostat is designed for standard commuting, staying completely closed until the engine gets quite hot to prioritize cabin heating and emissions. On a track or modified car, however, waiting that long means you start your hot laps with a cooling system that is already heat-soaked.

The Mishimoto Racing Thermostat solves this by opening at a significantly lower temperature than the OEM unit. By opening earlier, it allows coolant to begin circulating through your radiator sooner, effectively increasing your thermal buffer and keeping your engine temperatures stable under demanding conditions.

Depending on your generation, the Mishimoto thermostat drops the opening threshold significantly:

• NA Version: Opens at 68°C (154.4°F) compared to the factory ~82°C. Perfect for dedicated track cars and high-horsepower forced induction builds needing maximum early cooling loop engagement.
• NB Version: Opens at 80.5°C (177°F) compared to the factory 90.5°C (195°F). Offers a great cooling baseline for high-performance street and track cars.

By initiating radiator cooling earlier, your entire cooling system operates more efficiently, protecting your cylinder head gasket and helping keep oil temperatures in check during sustained high-RPM driving.

Street & Climate Advice:

Because this thermostat allows the cooling cycle to start much sooner, cars driven in cold winter climates may take longer to reach full operating temperature, which can affect cabin heater performance. If your MX-5 is a dedicated summer toy, track machine, or boosted build, this is a highly recommended upgrade.

For the ultimate cooling package, we highly recommend installing this alongside a high-flow aluminium radiator and our SkidNation Coolant Reroute Kit to ensure even temperature distribution across all four cylinders.

Note: This product includes the thermostat only. We recommend picking up a fresh thermostat housing gasket or O-ring for a leak-free installation.

Features:

• Direct fit for Mazda MX-5 NA or NB/NBFL (Select your version)
• Significantly lower activation temperature than OEM for earlier cooling loop engagement
• Helps reduce and maintain stable engine temperatures under extreme load
• Ideal upgrade for turbocharged, supercharged, or heavily driven track cars
• Mishimoto Lifetime Warranty

Compatible with 1989-2005 cars – NA (Mk1) and NB/NBFL (Mk2, Mk2.5).

Shipping worldwide.