What is a Restrictor Plate in NASCAR? All you need to know

Since being introduced in 1988, the Restrictor Plate has been a crucial safety component in NASCAR. This was done to reduce the chances of high-speed crashes on Superspeedways and allow for the pack to bunch together more easily during caution periods.

After Bobby Allison’s horrific Daytona wreck in 1987, where a high-speed engine blowout led to a series of events, the stock car racing organization decided to implement a device to clamp down the power of the engine to avoid a repeat of such incidents. This resulted in the creation of the Restrictor Plate.

Made using stamped aluminum, the plate consists of four drilled holes in the center, ranging from 0.875 inches and 1 inch in diameter. It is fixed in the car's intake system, between the carburetor and the intake manifold, to drastically reduce the flow of both air and fuel in the engine. This results in a reduction of both the power and torque output of the motor, thereby affecting the top speed and acceleration characteristics, respectively.

While it was deemed a safety device, drivers and teams complain about the plate reducing the fun element associated with racing. Some have also complained that Restrictor Plates were responsible for several multi-car collisions, as the plates allowed drivers to bunch together, even at speeds of around 200 mph.

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Here's why NASCAR switched from Restrictor Plate to Tapered Spacers after the 2019 season

With the evolution of components, materials, and overall aerodynamics in a race car, NASCAR decided to move on from Restrictor Plates to Tapered Spacers. This change was implemented after the end of the 2019 season.

Restrictor Plates had a successful run until the 2013 Daytona multi-car crash, which saw 28 spectators getting injured by the debris from Kyle Larson's car. Drivers blamed the plate for creating a situation where cars were bunched together, making overtaking a hassle.

While NASCAR officials decided to do away with the plate, they implemented a more precise solution in the form of Tapered Spacers. Unlike the uniform and paper-thin Restrictor Plates, these spacers have four cone-shaped and tapering holes. This allows for a more consistent airflow, which results in a better response from the throttle.

This resulted in an improved confidence level in a driver when trying to make a pass or engaging in wheel-to-wheel racing. Also unlike the plates, spacers could be implemented on all tracks by making subtle changes to their structure.

With an overall good response from using Tapered Spacers, NASCAR implemented two different horsepower packages with the next-gen cars in 2022. The first one uses larger spacers to generate 670 hp of power (for all tracks), while the second one with smaller spacers helps put out 510 hp of maximum output (for Daytona, Atlanta, and Talladega circuits).

This change seems to have made racing more interesting for drivers and fans alike.