Ultra light weight and wind tunnel tested.
Used in conjunction with 3″/75mm tube ducting and a 3″/75mm plenum results in maximum cooling efficiency for your cooling system.
NACA ducts bring air into a vehicle with minimal increase in drag. The purpose of a NACA duct is to increase the flow rate of air through it while not disturbing the boundary layer.
When the cross-sectional flow area of the duct increases, the static pressure decreases and makes the duct into a vacuum cleaner without the drag effects of a plain scoop.
The reason why the duct is narrow, then widens in an arc is to increase the cross-sectional area slowly so that airflow doesn’t separate and cause turbulence and drag.