The Mazda Rotary Engine makes a lot of power when cooling temperatures (oil and water) are in the range of 180-195, anything higher and you lose horsepower & torque.

For 90% of all rotary engined cars still being driven, this is a non-issue. If power and reliability is of importance and you like to stay high on the rpm’s this is for you.

Radiators are for one thing only, cooling. The right radiator is the difference of adequate cooling and proper cooling when pushing it hard. What the Mazda Rotary engine doesn’t like is temporary spikes in temperature because of hard driving, this increases the potential for rotor housing failure by many times over. 

Koyo Radiator Mazda Rx8
Every car is different, every type of driving is different. Get the right radiator for your car and driving style.

For the Rx8, here in Colorado the stock radiator is adequate for normal driving. We do recommend that if you are going to drive the car as it was designed, upgrade to the larger (30%) core types from KoyoRad.

Please see the pics below for reference.

The other component that must be 100% is the lower pan, remove it, break it / tear it and the engine will run hot until it breaks. I see a lot of engine rebuilds coming in with this pan damaged. Please note that the coolant temp gauge on the dash is not going to swing enough to tell you that the engine is overheating.

I also recommend that the oil coolers on the Rx8 be removed, fins straightened and our stainless steel mesh covers be installed. These improve the damage resistance and keep oil temps in their proper range. If the car is to be used for track days, add in the oil cooler pills (removing the OEM thermostats) for consistent oil flow / performance.

These are solid upgrades and while you are at it, put a new sub radiator tank in or upgrade to a Bennet Built aluminum tank (with built in sensor). Quality matters.