Ten of the Greatest Uses of NACA Ducts in Automotive History

By Ronan Glon

June 27, 2014

The NACA duct was designed in 1945 by the National Advisory Committee for Aeronautics, a federal agency that laid the groundwork for NASA as we know it today.  NACA engineers initially designed the duct as a way to feed air into an airplane engine without adding an excessive amount of drag, but it was seldom used because it provided a very limited amount of airflow.
Although the NACA duct was ill-suited to airplane engines, it became a popular feature on race cars starting in the 1950s.  Its design is simple: Mounted flush with the body, the duct captures air as it goes over the car and routes it to wherever it is needed.  The NACA duct has cooled brake components, radiators and interiors, and it has been used as an air inlet for naturally-aspirated engines.
The NACA duct was gradually adopted by engineers designing cars for all kinds of race series including Formula 1, Dakar and NASCAR.  Like many race-proven parts, the duct quickly found its way into the world of production cars where it was frequently used by European manufacturers in the 1960s and 1970s.
We’ve compiled a list of ten iconic cars equipped with at least one NACA duct. Let us know what your favorite NACA duct-equipped car is in the comments section below.
1. Alfa Romeo Montreal
The Alfa Romeo Montreal didn’t have a NACA duct when it bowed as a concept car at the Expo 67 that took place in Montreal, Canada, in 1967.  Alfa records show the duct was added to the production car almost as an afterthought in order to reduce the visual mass created by the sizable bulge on the hood.  The duct is not functional, but it adds an extra touch of sportiness to the Montreal’s muscular front fascia. 
2. Dodge Viper
Using data gathered in a wind tunnel, Dodge engineers added a NACA duct to the front end of the Viper when the GTS model was introduced in 1996.  The duct quickly became one of the Viper’s defining styling cues, and a more stylized version of it is prominently found on the latest iteration of the coupe.
3. Ferrari F40
The Ferrari F40 featured no less than eight NACA ducts, and select race-spec models boasted a couple more.  The ducts ranged from small ones mounted on the hood to large ones located right below the belt line.  The latter ducts were inspired by earlier Ferrari designs like the iconic Dino 246 GT and the 308. 
4. Lamborghini Countach
The Lamborghini Countach is remembered as one of the most iconic supercars of the 1970s thanks in part to its V12 engine.  Located directly behind the passenger compartment, the 12-cylinder mill got almost no air flow so large NACA ducts were fitted on both sides of the car in order to feed air into the two radiators that kept the temperature in check.  
5. Lancia Stratos
The Lancia Stratos was penned by Marcello Gandini, the same man who also designed the Alfa Montreal and numerous NACA-equipped Lamborghinis including the Countach, the Espada and the Jarama.  Unsurprisingly, the Stratos features a small NACA duct behind each side window but they are often partially hidden by a spoiler.
6. Porsche 924 Turbo
Drawing from experience learned from years of turbocharging the 911, Porsche launched the 924 Turbo in 1979 in order to fill the gap between the naturally-aspirated 924 and the 911.  In addition to routing fresh air into the engine bay, the NACA duct on the hood helped the 924 Turbo stand out from its less expensive naturally-aspirated sibling.
7. Renault 5 Turbo
The Renault 5 Turbo was jam-packed with technology borrowed from Renault’s Formula 1 cars.  The most obvious example is its turbocharger - a technology that Renault started using in 1977 on its first-ever F1 car - but the NACA duct that was found on the driver’s side fender was also transferred directly from the F1 program.
8. RUF CTR Yellow Bird
Even over 20 years after its launch, the RUF CTR Yellow Bird wears what is considered one of the shapeliest applications of the NACA duct: Over the Porsche’s 911 rear haunches.  Unfortunately, the ducts didn’t work as planned so they were deleted on later models.
9. Shelby GT350
While many performance-focused Mustangs in the 1960s and 1970s used oversized scoops to capture air, Shelby’s GT350 stood out with three NACA ducts on the hood and two more discreet ducts located on each front fender.  Perhaps inspired by the GT350, Ford added two large NACA ducts to the hood of the 1971 Mustang Mach 1.
10. TVR Vixen
The TVR Vixen is proof that NACA ducts are not exclusively used on supercars.  While the Vixen was certainly designed to provide a lively driving experience, the tiny coupe hardly broke any speed records with its Ford-sourced four-cylinder engine.  It should be noted not all versions of Vixen had NACA ducts.