Restrictor plate
In 1995 Toyota Team Europe used an illegal device to bypass the restrictor (allowing an estimated extra 50 hp).
The following race at Talladega that year would be run with a smaller carburetor, however, NASCAR mandated the use of the restrictor plate at the end of the season.
The restrictions are in the interest of driver and fan safety because speeds higher than the 190 mph range used for Daytona and Talladega risk cars turning over through sheer aerodynamic forces alone.
Drivers such as Rusty Wallace have cited data showing that the roof flaps used on the cars cannot keep them on the ground above 204 mph.
[citation needed] The drawback to the use of the restrictor plates has been the increased size of packs of cars caused by the decreased power coupled with the drag the vehicles naturally produce.
The shape of the spacer helps a car funnel more air smoothly into the manifold, increasing fuel performance, while ensuring airflow is still restricted.
[5] Starting in 2022, restrictor plate rules were used for Atlanta Motor Speedway because of concerns over speed after the circuit was repaved and reconfigured to 28 degree banking.
Allison's Buick LeSabre blew a tire going into the tri-oval at 200 mph (320 km/h), spun around and became airborne, flying tail-first into the catch fencing.
In 1992, when the Busch Grand National series began racing at Talladega, the plates were implemented, in keeping with their use at Daytona.
The use of restrictor plates, intended as an emergency measure pending a more permanent replacement in any event, was discontinued at New Hampshire for the following race for Cup only.
[citation needed] Restrictor plates remain a permanent fixture on the Modifieds and the racing has often broken 20 official lead changes for 100–125 laps of competition.
A frequent criticism of restrictor plates is the enormous size of packs in races, with "Big One" wrecks as noted above singled out for condemnation despite the greater violence of smaller-scale crashes on unrestricted tracks.
In restrictor plate racing, the packs have brought about an often-enormous increase in positional passing; at Talladega Superspeedway, the Sprint Cup cars have surpassed 40 official lead changes sixteen times from 1988 onward, including both 2010 Sprint Cup races at Talladega, which had 87 official lead changes in the regulation 188 laps.
(The 2010 Aaron's 499 had 88 lead changes, but the 88th – the race-winning pass by Kevin Harvick – was on the last lap of the third attempt at a green-white-checkered finish).
Daytona International Speedway has generally been less competitive because the age of the asphalt (the track was repaved in 1978 and again in 2010) has reduced grip for the cars and thus handling has impeded passing ability to a significant extent.
