Supercool Low Temperature High Flow Thermostat

Cool Your Engine! The Fuji Racing Supercool Thermostat has successfully completed a rigorous testing period throughout 2022, and we are thrilled to announce that it is now available for public purchase. The primary advantage of the Fuji Racing Supercool Thermostat lies in its ability to regulate engine coolant circulation more effectively. By opening at a lower temperature compared to standard thermostats, this component allows coolant to begin flowing through the engine and radiator sooner. This early circulation plays a crucial role in maintaining lower overall engine temperatures, which can improve efficiency and performance during both daily driving and high-demand situations, such as track days. The Fuji Racing Supercool Thermostat is designed to operate at an optimal temperature of 71°C. In contrast, the OEM Subaru thermostats open at higher temperatures: 78°C for turbo models and 82°C for naturally aspirated models. This difference in operating temperatures enables the Fuji Racing thermostat to release the coolant into the radiator quicker, thus ensuring that heat is expelled more effectively from the engine. One of the standout features of the Fuji Racing Supercool Thermostat is its larger opening. With a diameter of 41mm, it surpasses the OEM’s 39mm opening, facilitating increased coolant flow. This design improvement is particularly advantageous in high-performance scenarios where maximizing coolant circulation is vital for maintaining engine stability. Our testing was conducted on a modified 2005 WRX STi, which featured a 2.1 stroker engine. Throughout this testing regimen, we simulated both daily driving conditions and intense track sessions, accumulating a total of over 6,000 miles. Notably, even during summer days reaching temperatures of 30°C, coolant temperatures never exceeded 95°C—a strong indicator of the thermostat’s efficiency. During daily driving, the performance of the Fuji Supercool Thermostat matched that of the OEM thermostat, with consistent heating levels ensuring optimal functionality for passenger comfort. The testing setup included a variety of components: an OEM-standard coolant radiator, an OEM cast impeller water pump, the Fuji Supercool Thermostat, a front-mounted intercooler, and a front-mounted oil cooler. For this entire system, we utilized Millers Alpine antifreeze, a product known for its reliability and performance under demanding conditions. Throughout our tests, the coolant temperatures remained stable with no significant fluctuations, demonstrating the effectiveness and reliability of the Fuji Racing Supercool Thermostat in maintaining engine health.