M-Tuned Radiator Coolant Reroute Kit 1.8L Mazda Miata MX5

  • $249.99
    Unit price per 


Why the Miata has a built in problem. The Miata's engine was designed for a front wheel drive car then turned 90* lengthwise in the Miata.
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.

The M-Tuned system returns the coolant flow path to the correct configuration used before the Miata came along. In addition, the kit retains full functioning of the original system including correct sensor locations for the stock ECU, heater, bypass circuit operation for proper warm-up and cold over-pressure protection.

Attention 01-05 owners: Mazda changed the head gasket design for these years to restrict flow to the #1 cylinder. Not a real fix but it does allow the 01-05 to run a tiny bit cooler than the previous years. Because of this change some people thought the coolant reroute can cause uneven cooling in the cylinder head. Through our experience and testing of this kit on 01-05 Miatas, both on the street and on the track, we have not seen any adverse effects from using this kit on any of the 01-05 cars, and have seen nearly all the cooling benefits experienced on ’90-’00 cars. If you have reason to replace the head gasket on your 01-05 engine, consider using a 94-00 head gasket.

Kit includes everything you need to complete the reroute conversion:
-Reroute adapter
-Remote Thermostat housing
-5/8" hose barb for heater
-195º thermostat
-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