Why NASCAR Put Restrictor Plates on Race Cars

NASCAR adopted restrictor plates to slow cars at its fastest tracks—primarily Daytona International Speedway and Talladega Superspeedway—after dangerously high speeds and airborne crashes in the 1980s threatened driver and spectator safety. The most immediate catalyst was Bobby Allison’s 1987 Talladega crash, which sent his car into the catchfence at more than 200 mph. In 2019, NASCAR replaced traditional restrictor plates with tapered spacers that achieve a similar goal of limiting horsepower while refining drivability; the superspeedway-style package remains in use today at Daytona, Talladega, and since 2022, the reconfigured Atlanta Motor Speedway.

The Safety Imperative Behind Restrictor Plates

By the mid-1980s, Cup Series cars were qualifying at over 210 mph at Talladega. On May 3, 1987, Bobby Allison’s car became airborne after a tire failure and tore into the frontstretch fencing, narrowly avoiding the grandstands. That near-disaster underscored the risk of cars lifting off at ultra-high speeds and the limits of existing safety systems. Starting with the 1988 Daytona 500, NASCAR mandated restrictor plates at Daytona and Talladega to cut horsepower, lower terminal speeds, and reduce the likelihood of catastrophic, fence-destroying crashes.

How Restrictor Plates Worked

Restrictor plates are thin metal plates with carefully sized openings installed between the carburetor and the intake manifold (on the carbureted engines used during the era). The smaller the opening, the less air the engine can ingest, reducing fuel flow and lowering horsepower. At the superspeedways, this typically slashed output by roughly 40–50 percent compared to unrestricted engines, which in turn curbed top speeds and the energy in crashes.

Key Moments in NASCAR’s “Plate Racing” Era

The following timeline highlights pivotal developments that explain why and how NASCAR used restrictor plates—and what replaced them.

• 1987: Bobby Allison’s Talladega crash and Bill Elliott’s 212.809 mph qualifying record at the same track crystallize safety concerns.
• 1988: NASCAR mandates restrictor plates for Cup cars at Daytona and Talladega.
• 1994: Roof flaps debut to counteract lift when cars spin backwards, complementing plates.
• 2001–2010s: Multiple multi-car “Big One” crashes at plate tracks fuel debate about pack racing versus speed reduction.
• 2019: Traditional restrictor plates are retired in favor of tapered spacers that still limit airflow/horsepower but with smoother delivery.
• 2022: Atlanta’s reconfiguration creates superspeedway-style pack racing; NASCAR applies a similar reduced-horsepower, high-drag package there.

Taken together, these milestones show a consistent emphasis on keeping speeds within a manageable envelope while evolving the technology from blunt restriction (plates) to more refined solutions (tapered spacers and aero changes).

What Changed in 2019: From Plates to Tapered Spacers

While fans still say “plate racing,” NASCAR no longer uses the old stamped plates. Tapered spacers—precisely machined metal blocks with tapered holes—now regulate airflow. The change aimed to produce similar speed control with better throttle response and more consistent engine behavior. As rules evolved with the Next Gen car, NASCAR set specific horsepower targets for different track types; at the superspeedways, the package remains focused on limiting top speed and containing crashes.

Where and Why They’re Used Today

Speed control devices are applied where pack dynamics and ultra-high speeds intersect—tracks with long straights and high banking that encourage flat-out running. These venues demand strict horsepower management to keep cars from going airborne and to protect fans and drivers.

• Daytona International Speedway: Longtime home of “plate” (now spacer) racing, including the Daytona 500.
• Talladega Superspeedway: NASCAR’s fastest oval, where the safety rationale first became urgent in 1987.
• Atlanta Motor Speedway (since 2022): Reprofiled to race like a superspeedway, using the reduced-horsepower ruleset.

The common thread is risk mitigation: these tracks produce sustained, nose-to-tail packs at very high speeds, necessitating strict engine output limits and complementary aerodynamic rules.

What the Policy Achieved—and the Trade-offs

Restricting airflow curbed raw speed and helped prevent fence-destroying, spectator-endangering crashes. But it also reshaped the on-track product, creating tightly bunched packs where drafting strategy often outweighs outright engine dominance. The approach has clear benefits and downsides.

Benefits

These are the primary benefits NASCAR sought—and largely achieved—by instituting restrictors and later tapered spacers.

• Lower terminal speeds reduce crash energy and the likelihood of cars becoming airborne.
• Enhanced spectator safety by reducing the risk of debris entering the stands.
• More competitive parity at superspeedways, emphasizing drafting skill over pure horsepower.

In aggregate, these benefits address NASCAR’s foremost responsibility: safeguarding competitors and fans without abandoning the spectacle of high-speed pack racing.

Trade-offs

Safety gains came with notable compromises that continue to fuel debate among drivers and fans.

• Pack racing increases the chance of multi-car “Big One” crashes, even if individual impacts are slower.
• Reduced throttle sensitivity can limit passing under some conditions, making track position and teamwork paramount.
• Manufacturers’ engine advantages are muted, shifting development toward aerodynamics and chassis setup.

These trade-offs shape strategy and racecraft, making superspeedways as much about positioning and cooperation as outright speed.

Bottom Line

NASCAR instituted restrictor plates—and now tapered spacers—to keep its fastest tracks safe by capping speeds and curbing the risk of airborne cars and catastrophic fencing failures. The policy emerged from urgent safety concerns in 1987 and has evolved with technology and the Next Gen era, remaining central to how NASCAR manages danger at Daytona, Talladega, and modern Atlanta.

Summary

NASCAR put restrictor plates on engines to slow cars at ultra-fast ovals after a series of high-speed, airborne crashes—most notably Bobby Allison’s 1987 Talladega wreck—threatened driver and spectator safety. Plates debuted at Daytona and Talladega in 1988 and were replaced by tapered spacers in 2019, a change that continues to limit horsepower while improving drivability. Today, superspeedway-style packages are used at Daytona, Talladega, and reconfigured Atlanta to manage speeds, contain crashes, and balance safety with the spectacle of pack racing.

What is the controversy with restrictor plates in NASCAR?

When the 2019 Daytona 500 rolled around, the restrictor plate sang its swansong. The contraption had been controversial since its debut in 1988, with many NASCAR fans and personnel chastising the horsepower-reducing component, citing that it may not be as safe as NASCAR originally thought.

Will NASCAR ever get rid of restrictor plates?

As of August 2023, NASCAR had already begun to phase out the use of restrictor plates in favor of tapered spacers. This change started in 2019 to improve safety and competition.

How fast would NASCAR go without restrictor plates?

Without restrictor plates, NASCAR cars at superspeedways could exceed 225 mph (362 kph), with one test reaching nearly 230 mph, but this speed is considered too dangerous to race in competition due to instability and extreme tire wear. Rusty Wallace’s 2004 test at Talladega, where he reached 228 mph with a Generation 4 car, highlights the potential speeds but also the safety risks, particularly the potential for cars to become aerodynamically unstable. 
Historical Context and Safety Concerns

• Bobby Allison’s crash: Opens in new tabThe need for restrictor plates was highlighted by Bobby Allison’s crash at Talladega in 1987, where his car became airborne and crashed into the fence at over 200 mph. 
• Demonstrated Speed: Opens in new tabIn 1987, Bill Elliott set a qualifying record at 212 mph at Talladega, showing what was possible before restrictor plates were introduced. 

This video shows Rusty Wallace’s experience driving at nearly 242 MPH at Talladega without a restrictor plate: 55sKenny WallaceYouTube · Mar 14, 2024
Unrestricted Speeds in Testing

• Rusty Wallace’s Test: Opens in new tabIn 2004, Rusty Wallace tested a NASCAR car without a restrictor plate at Talladega and reached speeds of up to 228 mph on the backstretch. 
• Dangers of Extreme Speed: Opens in new tabWhile this demonstrated speed potential, Wallace noted that “there’s no way we could be out there racing at those speeds… it would be insane”. He also described the car becoming aerodynamically unstable, with the front end lifting. 

Why Restrictor Plates Are Necessary

• Airflow and Horsepower Reduction: Opens in new tabRestrictor plates, or the later “tapered spacers,” limit the airflow and fuel to the engine, reducing horsepower and controlling speeds on superspeedways like Daytona and Talladega. 
• Safer Racing: Opens in new tabBy controlling speeds, NASCAR aims to reduce the risk of catastrophic single-car incidents and protect fans in the grandstands. 

Why did NASCAR start using restrictor plates?

NASCAR began using restrictor plates to slow down cars and improve safety on superspeedways, particularly after a significant crash at Talladega in 1987 where a car went airborne and damaged the catch fence, endangering fans. By reducing engine power and therefore top speeds, restrictor plates help keep cars on the track and reduce the likelihood of them becoming airborne. They also encourage tighter “pack racing” on large tracks, which many fans enjoy.
 
Reasons for Implemention:

• Safety: This was the primary reason for the 1988 implementation. High speeds on superspeedways created a risk of cars becoming airborne and flying into the grandstands, as seen in the 1987 Talladega incident where Bobby Allison’s car launched into the catch fence. 
• Speed Reduction: Restrictor plates limit the amount of air and fuel that can enter an engine’s combustion chamber, reducing its power output and thereby lowering the cars’ top speeds. 
• Pack Racing: By bringing speeds down, restrictor plates create larger, more densely packed groups of cars on the track. This “pack racing” phenomenon is a popular form of racing that fans enjoy. 

Historical Context:

• NASCAR first experimented with restrictor plates in 1970 and again in 1988, following a period of increasing engine power that resulted in speeds exceeding 200 mph on superspeedways. 
• While the restrictor plate has been controversial among drivers and teams, it is considered a necessary tool to manage speeds and enhance safety on specific tracks. 
• Today, while still used at superspeedways like Daytona and Talladega, NASCAR has transitioned to a different system called the tapered spacer for most other tracks to achieve a similar effect.