What is a Restrictor Plate?

Who loves restrictor plate racing as much as I do?

We have a while before the NASCAR Sprint Cup Series' next (and last) restrictor plate race of the year (Talladega on Oct. 20), but let's refresh our memories on what a restrictor plate is, shall we?

"A restrictor plate is a metal plate that's installed in the intake of the motor," said Zachary Ayers, driver for Bass-Ayers Racing. "This plate restricts the amount of air that the motor takes in."

Daytona and Talladega

There are two tracks (equaling in four races) in the NASCAR Sprint Cup circuit where the cars race with restictor plates: Daytona and Talladega.

Located in Daytona Beach, Florida, Daytona International Speedway was built in 1958 by NASCAR's founder, William France, Sr. and was the home of the first restrictor plate race in 1998 at the Pepsi 400 (now the Coke Zero 400).

Daytona is a 2.5-mile tri-oval. Because of its 31° banking in the turns and 18° banking at the start/finish line, drivers are able to reach a faster speed. (The fastest qualifying speed recorded at Daytona is Bill Elliott's 42.783-second run at 210.364 mph).

There are two races at Daytona International Speedway each year: the Daytona 500 and the Coke Zero 400. Both races first ran in 1959.

The first Daytona 500 also coincided with Daytona International Speedway's opening in 1959. Additionally, since 1982, the Daytona 500 has been NASCAR's season-opening event.

The Coke Zero 400, as mentioned, was NASCAR's first restrictor plate race. This race has been held over Fourth of July weekend since 1988.

Two NASCAR races are also held at Talladega Superspeedway (formerly Alabama International Motor Speedway) in Talladega, Alabama.

Construction for "Dega" began in 1968 when William France, Sr. wanted a track faster and longer than Daytona International Speedway.

Like Daytona, Talladega is a tri-oval, but it is has a length of 2.66 miles.

NASCAR first raced in Dega in 1969.

The Aaron's 499 in late April/early May is the first of two races at Talladega Superspeedway in NASCAR's season.

The second race is the Camping World RV Sales 500, which is held in October as a part of the Chase.

Drafting

At these two race tracks, as mentioned, drivers can reach very high speeds. This is where the restrictor plate comes into play.

The restrictor plates "ultimately slows the car down," said Ayers.

Why are Daytona and Talladega two of the most anxiously anticipated races of the season? Because of the drafting.

"With the motors restricted (by the restrictor plates), drivers will draft with other cars," said Ayers, "which drastically cuts down the wind resistance to almost zero, allowing their car to go faster. That's how drivers pick up/find speed."

This is a picture illustrating some drafting at Talladega.

Picture retrieved from here.

Drafting like this often causes what we call "The Big One." "The Big One" is a crash that results in a lot of cars getting damaged, and it is caused by drivers running in packs.

When there are multiple cars running side-by-side like this and something goes wrong, it causes multiple cars to get caught up in the accident. Here is a video of "The Big One" from Talladega 2013.

So, who's excited for the last restrictor plate race of the year?

Some information for this post was retrieved from:
International Speedway Corporation
Wikipedia (Daytona)
Wikipedia (Talladega)