Third generation RX-7's are notorious for having marginal cooling systems. Simply put there isn't enough space under the hood to get adequate airflow nor enough room to mount a properly sized radiator. Perhaps in unmodified form the stock radiator might be adequate but the minute power increases are demanded of the powertrain and when driven hard for extended periods of time the inadequacies of the stock cooling system become readily apparent. This is perhaps the reason that one of the first things to add to your vehicle is an aftermarket coolant temperature gauge. The stock temperature gauge is so heavily weighted so as to be next to useless until it is too late. Given the intolerance of rotary engines to an over-temperature condition this gauge is totally useless except to inform the driver when to pull over and call a tow. Therefore in the interest of preserving my car for track use I decided to install the Mazda Competition upgraded race radiator.
The Mazdacomp radiator consists of a core section 150% thicker than the stock unit and has welded aluminum end tanks verses the stock radiator with plastic end tanks. In defense of the OE radiator it was about half the weight of the Mazdacomp unit. In this area though I think dependability outweighs the benefits of saving a few pounds. installation was fairly straight forward. The Mazda service manual was very helpful. To begin one must remove all the intake plumbing and the intercooler. The airbox, intercooler ducting and battery and tray must also be removed. Because the radiator is attached at the lower points to the front sway bar mounts, the undertray and sway bar and mounts must also be removed.
Comparison: Mazdacomp (top), Stock with fan assm. (bottom)

Oh my God! What have I done? (radiator and plumbing removed)
New Mazda Competition radiator installed
with new hoses (bottom)
In my case I merely had to remove the radiator support plates from the CWC mounts and not remove the mounts themselves. The manual specified removal of the stock radiator from below but I found removal from above to be the least painful. I'm sure if the car had been on a lift the lower route would have been easier. Removal from below would also require slightly bending the AC condenser out of the way to clear the path for removal. With the old radiator removed installing the Mazdacomp was easy. transfer the fans from the stock unit and drop in the new assembly. While installing the Mazdacomp I also decided, while I had everything apart, to also replace the main upper and lower radiator hoses and also use screw clamps in lieu of the OE spring clamps. However, given the simplicity of the dropping in the upgraded radiator itself there is more work to be done. The OE radiator is sealed to the car with lots of foam. the Mazdacomp on the other hand has only some alloy flanges. So one must fabricate side shields to seal the radiator. I used thin-wall SS sheeting and formed the side shields around existing piping and used prethreaded holes as locations for fixing the shields in place. See pictures below
Additionally, proper ducting must be made in the nose of the car to ensure that every last ounce of airflow entering the nose goes through radiator. Many have said, and who I believe, that a properly ducted stock radiator will outperform a poorly ducted upgraded radiator. Now in my case I want a properly ducted upgraded radiator - the best of both. With everything buttoned up I refilled the system and went through he three day burping process and all was well at the next track outing. Ambient temperatures were cool so engine temperatures were not an issue so I shall have to wait until next year to see what effects the bigger radiator will have but I'm sure it will be beneficial.
Left side custom fabricated side shield ducting
Right side custom fabricated side shield ducting



This page last updated April 17, 2001
rotorphiles have visited this page since April 17, 2001

If you would like to contact me and converse about my experiences with my 7:
please feel free to send an e-mail to

Disclaimer: All images contained on this page are the sole property of C. Regan or were collected from the public domain, unless otherwise indicated. If any image contained on this page is considered private property please contact Christopher Regan.Webcounter supplied courtesy of