Due to cars hitting speeds of 206 MPH during the Bud Shootout on Saturday night, Nascar has decided to change the size of the restrictor plate to 1/64th of an inch.
This change should drop about 10 horsepower from the motors, resulting in speeds just under 200 MPH for Sunday’s race. These changes help to keep the cars at speeds that will keep both the drivers and fans safe.
Nascar holds these plates in a box and they are distributed by a Nascar official in no particular order so that no one team has the same plate every race, this is done to keep things fair. The plates are then collected after the race and given back to Nascar until the next super speedway race where they are used and redistributed once again.
Nascar uses restrictor plates at both Daytona and Talledaga
Picture borrowed from:www.dipity.com
Here’s a video I found on YouTube from last year,Darrell Waltrip describes how these plates work.