Ultra light weight and wind tunnel tested, our 4 inch NACA duct provides over 55% more airflow than standard 3 inch NACA ducts. Used in conjunction with 4 inch tube ducting 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 through it 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, but without the drag effects of a plain 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.

Also available in dual 4" versions.

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