Parts Spotlight: Mazda Motorsports’ Radiator for NB Miatas

New triple-pass radiator from experts in cooling technology is a straight replacement for stock, and is Spec Miata approved

Part No.: 0000-01-5503-CR
Racer Price: $750.00

When a racer’s nose is six inches off the back bumper of the car in front in a five-car draft, airflow through the radiator is not optimal. Mazda Motorsports saw a need for a better performing radiator for Spec Miatas, in particular the 1999-2005 NB Miata. For this, Mazda Motorsports turned to C&R, which has long provided advanced cooling technology for NASCAR, IndyCar and IMSA sports car applications. The company is now a part of PWR, which has experience in F1 and rally as well. Consequently, C&R turned out to be the ideal partner for the development of a new NB Miata radiator that is not only approved for Spec Miata but will also work well for NB racers competing in other categories.

C&R didn’t just take an existing core and slap some mounts on it to make it fit. It was a research and development process that took the radiator from a single-pass design to a triple-pass design for optimal function in the Miata.

“A single-pass design typically has an inlet on one side and an outlet on the opposite side, and the coolant makes one pass through the entire core,” explains Phil Cook, part of C&R’s Sales and Tech Support Group. “For whatever reason, Miatas like a triple pass. In a triple pass, we actually put a baffle about six inches below the inlet so the coolant will pass through one third, then it goes back the other way, then there’s a baffle about six inches above the outlet, so there’s another pass, and then the last pass will be the bottom third of the radiator. The water actually goes three times through one-third of the core. It separates the radiator into three smaller radiators.

“This process allows heat to transfer in three different cycles instead of one large process. The duct work and nose openings are critical in these cars, and it happens that the last pass is at the lower area of the grill, where it gets the most airflow across that particular part of the radiator. That’s one of the big reasons a triple pass works so well in this particular application.”

The radiator uses C&R’s proprietary extruded tube race core and fin design and works with the stock fan – a Spec Miata requirement. It’s a direct replacement for the stock radiator, with no modifications required. It also incorporates a couple of other unique features.

“It may seem small, but we extended the top plate to help direct airflow. That’s something that’s not on the stock radiators. We also incorporated a zinc anode, which will help reduce the potential for corrosion. We suggest people run corrosion inhibitors, but the zinc anode will help as well,” says Cook.

To order, log on to the parts store or call (800)435-2508.
Pricing is subject to change.