Restrictor Plate

A restrictor plate is a flat metal device with holes that limits how much air can enter a race car's engine, which reduces the engine's power and keeps speeds lower for safety reasons.

Think of a restrictor plate like putting your hand partially over a straw while drinking - it limits the flow and makes everything slower. In racing, this aluminum plate sits between the engine's air intake system and blocks some of the airflow that the engine needs to create maximum power.

Racing organizations use restrictor plates primarily for safety. When cars go too fast on certain tracks, crashes become extremely dangerous. By limiting engine power, restrictor plates keep speeds at safer levels while still allowing exciting competition.

NASCAR made restrictor plates famous by using them at their fastest tracks - Daytona and Talladega - from 1988 to 2019. These superspeedways were so fast that officials worried about cars becoming airborne during crashes, which could endanger both drivers and spectators in the stands.

The restrictor plate creates what's called "pack racing," where cars run very close together in large groups because no single car can pull away with superior engine power. This often leads to dramatic finishes with many cars having a chance to win.

While NASCAR has mostly moved to a similar device called a "tapered spacer," restrictor plates are still used in other racing series. Formula 3, sports car racing, and various amateur racing classes use air restrictors to keep costs down and competition close.

The restrictor plate essentially levels the playing field by preventing teams with bigger budgets or better engine technology from dominating purely through horsepower. Instead, driver skill, strategy, and teamwork become more important factors in determining race winners.