Designed around Setrab 25 Row Dual Oil Coolers, Sakebomb Garage 1993~1995 Mounting Kit. Matching 99 Spec Front Bumper.

Reach out for custom design requests. Located in Irvine, California. We 3D scan your specific front bumper and heat exchanger mounting and build the ducts to your specification.

Performance via Efficiency

A turbocharged rotary engine faces inherent thermal challenges. Enormous amounts of air and fuel are compressed into a compact combustion chamber, creating intense localized heat. The temperature distribution across the engine is highly uneven—areas near the spark plugs experience significantly higher thermal loads. The coolant passages within the rotor housings alone cannot dissipate this heat effectively, leaving the rotors vulnerable to excessive temperatures.

For this reason, the 13B-REW engine in the RX-7 FD relies heavily on its oil cooling system. Recognizing this challenge, Mazda equipped the RX-7 FD3S R1 and R2 performance trims with dual front-mounted oil coolers from the factory—a rare and costly solution at the time. By contrast, many of its turbocharged contemporaries, such as the Nissan Skyline GT-R R32, lacked oil coolers in base models. Even today, modern turbocharged performance cars like the Honda Civic Type R (FK8/FL5) omit oil coolers to reduce manufacturing costs, underscoring just how dedicated Mazda’s approach was three decades ago.

In 1999, Mazda revised the RX-7 FD’s front bumper to improve heat management. The new design featured oil cooler openings ~75% larger than before. Engineers also integrated dedicated vents behind the front wheels, allowing hot air from the oil coolers to exit efficiently.

However, one crucial aspect remained underdeveloped was the ducting between the bumper openings and the oil coolers. Without proper sealing and direction, much of the incoming air dissipates before reaching the cooler cores, compromising efficiency. This presents an excellent opportunity for improvement.

The AZZURRO RACING Oil Cooler Duct is engineered for track-focused builds where consistent oil temperature control is critical. Its geometry controls flow separation and minimizes drag caused by the heat exchangers. By improving ducting efficiency, it allows for smaller and lighter coolers, or enables higher engine output and longer, more demanding track sessions.

Maximum Temperature Control

When paired with large dual oil coolers, such as the Setrab 25-row units, it’s possible to overwhelm the oil thermostat. As a result, oil temperatures can drop below 60°C during cruising, even when coolant temperature has stabilized around 80°C. Many FD owners resorted to makeshift solutions—like inserting cardboard behind the bumper—to help the engine retain heat.

The AZZURRO RACING duct for the FD3S integrates an elastic TPU block-off plate, allowing the car to maintain optimal oil temperature in colder conditions. The plate is secured with a set of magnets embedded into the duct and the block-off plate, therefore can be quickly removed or installed with no tools needed.

Material: Carbon Nylon (High-Temp, Endurable)

Lead Time: 1 Week.

Custom Design: Please inquire at weidong@azzurroracing.com