Why the MX5 has a built in problem. The MX5's engine was designed for a front wheel drive car then turned 90* lengthwise in the MX5.
To make it fit, Mazda's engineers moved the coolant outlet from the rear of the head where it belongs, to the front of the head. As a result of this backwards flow, only a small portion of the total coolant water flow goes around the 4th cylinder at the rear of the head so it runs hotter that the front of the engine.
In addition, not all of the heat the engine generates is being fed to the radiator so a much larger radiator must be used even for mildly tuned engines. Even a bone stock first gen Miata will kick on its cooling fans in steady state hot weather highway cruising with the A/C. As soon as you hit the track or add power the OEM routing becomes a major problem no matter how big the radiator or how much venting/ducting you have.
Kit includes everything you need to complete the reroute conversion:
-Remote Thermostat housing
-5/8" hose barb for heater
- Front outlet block off plate
- 1.6 has spare 1/8" npt outlet, 1.8 has 2x spare 1/8" npt ports
-36" coil reinforced silicone transfer hose
-Plugs for spare 1/8" npt ports
-All clamps, fasteners, seals needed for installation
Suits NA/NB MX5's 1989-2004