I know, I know, I promised that the new Nationwide car was going to be our next lesson but since we just finished with Daytona where they ran a new restrictor plate why not talk about that next? Plus I'm having some very big issues with my computer and the NNS car graphic I have.
Essentially a restrictor plate is a piece of metal placed in-between the carburetor and the intake manifold that limits the amount of air into the engine to mix with the fuel thus robbing the car of horsepower which in turns slows the car down.
Please see the much better explaination with the graphic below. If clicking on the picture does not make the image bigger than click on this link to make it bigger.
Graphic Courtesy NASCAR