Are restrictor plates still used?

No—at least not in NASCAR’s top series. Since 2019, traditional restrictor plates have been replaced by tapered spacers to limit engine power at high-speed tracks, a practice that continues in 2025. However, air-intake restrictors do remain in use in some other forms of motorsport, particularly sports car and rally competition. This shift reflects evolving safety, competition, and technical regulations across racing series.

What a restrictor plate is—and why it mattered

A restrictor plate is a flat metal plate with calibrated holes placed between the carburetor/throttle body and the intake manifold to limit how much air an engine can consume, thereby capping horsepower and top speed. In NASCAR, plates became synonymous with superspeedway racing at Daytona and Talladega starting in 1988, after frightening accidents underscored the need to keep speeds in check. While they effectively reduced velocity, they also created distinctive pack racing and sometimes limited throttle response, shaping both racecraft and safety outcomes for decades.

What NASCAR uses today

NASCAR retired the classic restrictor plate in 2019 in favor of a tapered spacer—a contoured insert that more precisely meters airflow and engine output. The spacer serves a similar purpose (limiting horsepower) but allows better drivability and finer control for rule-makers. With the Next Gen car era now well established, the Cup Series runs a lower-power “superspeedway” package—targeting roughly 510 hp—using tapered spacers at specific high-speed tracks; most other ovals use the higher-power package.

These are the NASCAR tracks where the superspeedway-style rules package (using tapered spacers to reduce horsepower) is currently applied:

• Daytona International Speedway
• Talladega Superspeedway
• Atlanta Motor Speedway (since its 2022 reconfiguration)

While the components and exact tuning evolve, the principle is the same: NASCAR caps power at these venues with tapered spacers rather than traditional restrictor plates, balancing safety with competitive racing.

Are restrictor plates used anywhere else?

Yes. Outside NASCAR, various series still rely on intake restrictors to control performance, manage costs, and enforce parity. The approach varies by sanctioning body, vehicle type, and whether Balance of Performance (BoP) tools like turbo boost limits or fuel-flow meters are used instead.

Examples of where restrictors remain common include:

• International sports car racing (certain GT and prototype classes) using air-inlet restrictors as part of BoP
• Rallying, including top-level categories that employ turbo restrictors to cap engine output
• Selected national or grassroots series where simple air-intake restrictors offer a cost-effective way to equalize performance

In contrast, some top-tier series (such as Formula 1) regulate performance via fuel flow limits, hybrid systems, and turbo boost controls rather than intake restrictor plates.

Common misconceptions

Even years after the change, fans and commentators sometimes call NASCAR’s current setup “restrictor plate racing.” Technically, that’s outdated. The Cup Series, and broadly NASCAR’s national series, use tapered spacers—not flat restrictor plates. The distinction matters to engineers and teams because tapered spacers provide smoother airflow characteristics and more predictable engine response while still achieving speed control.

Key timeline at a glance

Restrictor plates became part of NASCAR lore in 1988 at Daytona and Talladega. They were phased out after the 2018 season, with 2019 marking the introduction of tapered spacers to limit horsepower. When NASCAR launched the Next Gen car in 2022, the spacer-based approach continued, with a defined superspeedway package used at Daytona, Talladega, and reconfigured Atlanta from 2022 onward.

Summary

Traditional restrictor plates are no longer used in NASCAR; they were replaced by tapered spacers beginning in 2019, a policy that remains in effect in 2025. The function—limiting horsepower to manage speeds—remains, but the hardware and its on-track characteristics have evolved. Elsewhere in motorsport, intake restrictors are still common tools for performance control, especially in sports car and rally disciplines.