Which device was used from 1988 to 2014 to limit horsepower at Daytona and Talladega?

A restrictor plate was used to limit horsepower at Daytona International Speedway and Talladega Superspeedway. NASCAR introduced the device for Cup Series competition in 1988 after a dangerous 1987 crash at Talladega involving Bobby Allison.

The thin metal plate was installed between the carburetor and intake manifold. Its small openings restricted airflow into the engine, reducing horsepower and top speed at NASCAR's fastest tracks. The restriction also helped keep cars from becoming airborne through extreme aerodynamic forces, though pack racing created its own risks and distinctive strategy.

The commonly cited end date can cause confusion. Traditional restrictor plates remained in Cup competition through the 2019 Daytona 500, after which NASCAR adopted tapered spacers and additional aerodynamic measures. Thus, restrictor plates were certainly the device used during the 1988–2014 period described by the question, even though the broader plate era continued beyond 2014.