QMAX Coolant Reroute
90-05 MX5 Miata
The Qmax coolant reroute is the most effective design available, from the only shop on the planet that actually operates a multi national championship winning race team and runs a racing series. Others copy, none match its performance. A must have for any Miata experiencing cooling issues. No gaskets to leak. The only coolant reroute available that is competition proven on the worlds fastest Miatas. Our own 440whp, 8,000rpm two time Superlap Battle winning, record setting cars running a whopping 30psi of turbo boost run the same Qmax we offer you. Thousands in use around the world. Autocross, Time Attack, Road Racing, Enduro or just blasting down the highway, keep that B series Miata engine cool!
The B series engine in the Miata was designed for a fwd car. As with all inline 4 cyl engines, coolant entered one one end of the head and exited the other end in the fwd application. This simple path is the most efficient way to extract heat from the head. Mazda turned the engine 90° and tucked it up against the firewall in the Miata. This meant moving the coolant exit to the front, the same end of the head as the inlet. This poor flow path is the primary cause for overheating which is so common in the 90-05 MX5. Our reroute has a carefully engineered low profile adapter for the back of the head to retain the original front to back coolant path. Just this one modification will significantly reduce coolant temps. Even a bone stock Miata will run a bit hot, and the stock ECU will reduce ignition timing which hurts power and fuel economy. Performs as designed with OEM head gasket. No need to change head gasket type or style. Standard 195° thermostat optimized for use with stock ECU. Optional 180° thermostat for competition builds running a programmable ECU if so desired. Using the optional 180° with a stock ECU can result in overcooling.
Optional head block off plate
If you plan to remove the water neck, purchase the optional cylinder head block off plate. The kit includes a block off plate for the OEM water neck on the front of the engine.
Qmax Reroute Features
- Internally multi axis machined and radiused to maximize coolant velocity which is key to improving cooling efficiency
- Retain the use of your EGR pipe for emissions or CEL
- The OEM coolant temp sensor location is retained so the wiring harness does not need to be modified
- Spare 1/8 NPT ports are provided for aftermarket coolant temp, turbo feed or coolant pressure sensors
- All important hardware is stainless steel to increase service life
- High flow thermostat with same flow area as OEM
- Simple sealed adapter housing eliminates gaskets and finicky, leak prone threaded fittings. ZERO LEAKS!
- Convenient bleed port allows system bleeding with car level if you have COPS ignition
- Integrated thermostat housing for easy fitment and improved reliability
To learn more about your 90-05 Miata cooling system and how to improve efficiency, visit this tech article we wrote: NA/NB Cooling System Performance
Installation takes the average mechanic a few hours with common hand tools.
Download instructions here
Contents of QMAX Reroute kit – 100% complete kit, nothing else needed to install!
1x Reroute housing, Supermiata, 7075 T-6
1x Thermostat cover, Supermiata, 7075 T-6
1x (optional) Head coolant port block off plate, Supermiata, 7075 T-6
1x Coolant neck block off plate, Supermiata, 7075 T-6
3x M6 x 1 x 25mm BHCS, black oxide
1x 1- 11/16 inch retaining ring, HO-168SS
3x 1/8 NPT plugs, SS
1x Bleed screw assy Wilwood 220-0627
1x Worm drive hose clamp, 5/8″ Breeze 9416, liner SS
2x Worm drive hose clamp 1.25″, Breeze 9424, liner SS
1x 3/8″ NPT – 5/8″ hose barb, brass
1x M16 x 1.5 drain plug, zinc
1x 1.25″ reinforced silicone hose, 44″
1x 195* stainles steel high-flow thermostat (use Motorad/Stant 45849 for replacements. Alternatively, use Motorad/Stant 45848 if you want to run a 180* thermostat)
1x Sealant, Permatex 22071
Specialty tools recommended:
- Internal snap ring pliers like these: https://www.harborfreight.com/snap-ring-pliers-with-interchangeable-heads-60531.html
- Metric allen keys
- Plastic razor scraper. To remove old gasket material from head
- Lisle 24680 funnel