Every square inch of the Acura NSX exterior body panel surfaces, fluid shapes, air inlets, exhaust outlets and the positioning, shaping and thickness of its floating C-pillars serves to optimize aerodynamic efficiency and support dynamic driving performance.
The second-generation Acura NSX was designed with a total airflow management strategy to achieve critical cooling flow performance, while minimizing drag, and to provide precise downforce distribution between front and rear axles to help ensure vehicle stability at high speeds. This approach manages airflow not only under and over the exterior surfaces, but through the front and rear motor rooms.
Three main flows make up total airflow management:
- Through the NSX – Air flows through the front motor room, cools the power unit and brakes and provides downforce as it exits the hood and fender vents. The wheel wake management vents also minimize the flow disturbance from the front wheels.
- Under the NSX – A flat underbody helps anchor the NSX by promoting negative pressure under the vehicle. Ducts pull air in and through a hollow rear chassis casting to provide rear brake cooling in a patent-pending design. The air flowing under the body is maximized with another patent-pending design; the rear diffuser increases the negative pressure, enhancing rear downforce.
- Around the NSX – Air that exits the hood, fender and wheel wake management vents is strategically held tight against the side of the vehicle and re-introduced downstream through the intercoolers and over the rear integrated decklid spoiler. All the air flowing through, under and around the body converges to help manage the wake behind the NSX, thereby reducing overall drag.
Aerodynamic Downforce
The most important benefit of total airflow management is stability at high speeds for the driver, as well as maximizing power unit output and brake performance.
A 3-to-1 (rear-to-front) downforce ratio was determined to be the optimal downforce distribution for high‑performance driving. This complementing downforce balance maximizes the driver feeling of stability and traction at high speeds.
The greatest downforce is generated as six vortices of air flow across the rear decklid. Air flowing from below the car and exiting through carefully optimized rear diffuser fins further anchors the NSX to the ground. In a patent-pending design, these fins are not parallel to each other but are narrower toward the front of the car and wider at the rear. This unique design amplifies negative pressure, enhancing diffuser efficiency, which further maximizes downforce.
Cooling
All supercars must manage thermal loads, and the NSX is no different. With power unit components at both the front and rear of the NSX, engineers were challenged with how to move air efficiently through the front TMU room and the rear power unit compartment to help cool the brakes and maintain precise downforce management. To do so most efficiently, the total airflow management approach moves air through the front TMU room, out the hood, fender and wheel wake vents to stabilize this air flow once again along NSX door panels, allowing smooth air flow to be re-introduced into the rear engine room. In total, air passes through 10 heat exchangers along these flow paths to cool all power unit components.
In another example of how air moves through the NSX, air is also picked up by ducts in the underbody that cool the rear brakes. Moving large quantities of air across the friction brakes of the NSX means that drivers experience very little fade when braking during high-performance and track driving.
Typically, effective brake cooling at the rear of a mid-engine vehicle is difficult due to heat from the engine and transmission. Rear brake cooling on the NSX is enhanced by the innovative use of two air duct paths that have been designed into the hollow rear subframe. Air passing through the subframe is precisely directed to the rear brakes using specially-tuned air deflectors on the rear suspension arms.
Some air that enters the front TMU room also exits through the front wheel well to cool the brakes. As part of the total airflow management approach, this flow is carefully directed to perform its cooling function without disturbing flows downstream. As the flow cools the brakes and exits the front wheel well, the wheel wake management vents direct a thin, vertical sheet of air across the wheels that stabilize the turbulence that would otherwise be generated. The front fender vents support this effect.
Aerodynamic Development
Computational fluid dynamics (CFD) was used extensively during development to maximize the performance of all flow structures and to support hands-on experiments in wind tunnels during exterior design and power unit maturation. Along with the use of advanced CFD and wind tunnel and real-world testing, the development team also employed computerized lap-time simulation models of some of the world’s most legendary race tracks. These simulation models could then be run on chassis-dynamometers, allowing testing and validation of the computer models for the thermal management.
CFD image of Acura NSX
NSX has undergone extensive testing at the company’s state-of-the-art scale wind tunnel in Raymond, Ohio, using ultra-detailed 40-percent-scale models. The NSX has also been continuously verified and refined through full-scale testing in the company’s wind tunnel in Tochigi, Japan.
Air flows