Mazda Miatas are water-cooled vehicles, with a sophisticated cooling system designed to efficiently dissipate heat and maintain optimal engine temperatures. The cooling system in Mazda Miatas, specifically the NC generation, utilizes a combination of conduction, radiation, and convection to effectively cool the engine.
Coolant Flow and Circulation
The coolant enters the engine at the front, passes through the cylinder head, and exits the back of the head. This path is more effective for scavenging heated coolant compared to the original design, as it allows for better heat transfer and more efficient cooling.
The system incorporates an expansion tank with two return hoses, one from the rear of the engine and another from the top of the radiator. This setup helps evacuate any trapped air and uses the expansion tank as a swirl pot, ensuring that all coolant going into the heater is returned directly into the thermostat/pump inlet without passing through the radiator. This design choice is not optimal, as it doesn’t allow the coolant to cool off before entering the engine again.
Coolant Heating Provisions
In addition to the main coolant flow, there are two small lines that feed hot coolant to the throttle body and EGR valve. This is likely related to icing or the operation of these components at low temperatures. These lines could potentially affect the intake air temperature, especially in supercharged applications where the throttle body heats up the upper manifold significantly.
Cooling System Design Objectives
The Mazda Miata’s cooling system is designed to improve conduction, radiation, and convection for efficient cooling. The modified coolant path helps scavenge heated coolant more effectively, but there are some aspects of the system that could be improved, such as the lack of a valve controlling coolant flow to the heater and the use of oil to cool the stock oil cooler.
DIY Cooling System Modifications
For Miata owners interested in enhancing their vehicle’s cooling performance, there are several DIY approaches to consider:
- Sealing and Blocking Gaps: Sealing or blocking all the gaps around the radiator can improve airflow and heat dissipation.
- Undertray Installation: Installing an intact OEM undertray or a flat undertray that covers the entire bottom of the car can enhance airflow and cooling efficiency.
- Hood Vents: Adding hood vents can improve airflow and help expel hot air from the engine bay.
- “Big Cooling Kit”: Assembling a “Big Cooling Kit” with a reroute, 949 cross-flow radiator, thermostat, and a 1.3 bar silicone seal radiator cap can provide significant cooling performance improvements.
Technical Specifications
While the available sources do not provide detailed technical specifications, they offer valuable insights into the Miata’s cooling system design and functionality. The system is engineered to optimize conduction, radiation, and convection for efficient cooling, with the coolant path modified to scavenge heated coolant more effectively. There are opportunities for DIY modifications to further enhance the cooling system’s performance.