NASCAR will use an aerodynamic package for its May 19 All-Star Race at Charlotte Motor Speedway that will include an engine restrictor plate and front aero ducts that will move the air to the side of the car before it hits the front wheel.
The package, which also includes a six-inch spoiler equipped with additional six-inch “ears” at the ends, was used in the 2017 Xfinity Series race at Indianapolis. The Xfinity Series will use the package at Michigan, Pocono and Indianapolis this year.
By restricting air flow through the engine (the restrictor plate with holes of 7/8ths of an inch will cut horsepower by about 250) and creating more drag with the rear spoiler (which is normally just 2.375 inches high), NASCAR hopes to create a drafting dynamic similar to Daytona where drivers can be threewide or fourwide and run a similar speed.
— ESPN —