Why do you need a Coolant reroute for your Mx-5?
The B6 engine in the 89-93 Miata was originally designed to be packaged in a front wheel drive platform (like the Mazda 323). They decided to use this motor for the new rear wheel drive sports car by simply turning the engine 90 degrees in the engine bay. This created a few packaging complications.
The most well known and largest issue this caused is very common overheating problems. The 4th (rear) cylinder will get far too hot and the 1st cylinder (front) can run too cool in comparison.
There was a band aid fix in 2001, with a head gasket change, that restricts flow to the front cylinders and attempts to even out the cylinder coolant temperatures.
All NA / NB Miatas will see improved cooling from coolant reroutes, B6 or BP engine.
Best Miata Coolant Reroute Kits
I researched the different reroute kits extensively before buying one for my car. I ended up choosing the Supermiata Reroute, as I also liked their crossflow radiator and wanted the complete system. There are quite a few kits worth considering, and a few ways to do a DIY reroute.
Supermiata miata QMax reroute
This is a really well engineered and machined system. It has been extensively tested on the race circuits, with many national titles to show for it.
Flyin Miata Coolant Reroute Kit
This kit is well designed, including an engineering partnership with Colorado Mesa University to map out the cooling needs of the Miata engine. This kit is designed specifically to work well with water cooled turbo engines.
Cobalt mX-5 Reroute Kit
This is another well designed kit that has versions for EGR / non-EGR and different models. This kit features a nice molded hose that will work great with the stock radiator.
Skid Nation Miata Coolant Reroute
This is a newer coolant reroute to the market, but looks to be well made. It has a regular and premium version.
“Every day that I can work on my Miata, drive my Miata, or even think about my Miata is a good day.”— Dylan Howell, Only Miata