Ultra light weight and wind tunnel tested, our 4 inch NACA duct provides over 55% more airflow than standard 3" NACA ducts. Used in conjunction with 4" Neoprene Air Duct Hose and a 4 inch 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 while not disturbing the boundary layer. When the cross-sectional flow area of the duct is increased, you decrease the static pressure and make the duct into a vacuum cleaner (without the drag effects of a standard scoop). The reason why the duct is narrow, then suddenly widens in a graceful arc is to increase the cross-sectional area slowly so that airflow doesn’t separate and cause turbulence and drag.