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 Some NASCAR fans claim that the four
best races during the season are the events held at Daytona International
Speedway and Talladega Superspeedway. Daytona is the home of the Great
American Race, the Daytona 500. Talladega is known as the world's fastest,
largest, and most competitive track. Daytona, which held the first Daytona 500 in 1959, is a 2.5
mile tri-oval and its turns are banked at 31 degrees. Talladega was patterned
after the tri-oval shape of Daytona, but its length is 2.66 miles and its turns
are banked at 33 degrees. Records have been set and broken at these two mammoth
tracks. Bill Elliott came from nearly two laps down to win the Winston 500
at Talladega in 1985 without the aid of a caution flag. Elliott also set
the qualifying records at both Daytona and Talladega in 1987 with speeds of
210.364mph and 212.809mph respectively.
The weekend of the Winston 500 from
Talladega Superspeedway in 1987 changed the face of NASCAR racing. On Friday, Bill
Elliott set the fastest recorded lap speed in a stock car, 212.809mph. When the starting grid was
set on Saturday afternoon, it marked the first time that the entire field of cars for
the race exceeded the 200mph mark. Once the race got underway on Sunday
afternoon, one of the most frightening accidents in NASCAR history occurred.
Coming through the tri-oval on the front stretch, Bobby Allison blew a tire
and his car started sliding sideways. As the car slid down the track, it
went air born and slammed into the catch fencing just before the flag stand.
That entire section of the catch fence was ripped off and had it not been for
the two steel cables that reinforced the fence, Allison's car would certainly
have landed in the grandstands instead of bouncing back onto the track. The
race was red flagged for several hours while NASCAR officials and construction
crews rebuilt the catch fence. Once the race went back to green flag conditions, Bobby's
son, Davey went on to win the race, his first career win. This one race probably
changed the face of NASCAR more than any other. Bobby Allison's horrific crash
led to the implementation of restrictor plates. Though NASCAR did not require
restrictor plates until the start of the 1988 season, they did require a 390 CFM
carburetor for the remaining two events at Daytona and Talladega in 1987.
The smaller carburetor lowered speeds from the records set by Bill Elliott
earlier in the season to Davey Allison's pole speed of 198.085mph at Daytona and
Elliott's speed of 203.827mph at Talladega.
Diagram of a restrictor
plate.
(click on image to enlarge) |
A restrictor plate is a 3/16" thick
piece of aluminum that is 5 by 5 inches with four holes punched in it. It is
placed between the carburetor and the intake manifold. The restrictor plates rob
the engines of about 40% of their horsepower by limiting the amount of air flow into
the combustion chamber. They also make the engines run lower RPMs. The
plates are put in place by NASCAR officials; at the beginning of the weekend, in
the garage area. The restrictor plates are locked in a box and issued to teams
strictly by the luck of the draw. The restrictor plates are measured by
the width of the holes punched in the plate. For example, the first plate
used was a one inch restrictor plate. This meant that the width of each of
the four holes was one inch. The fastest pole speed achieved with the first
restrictor plate was 196.996mph by Ken Schrader for the 1989 Daytona 500. NASCAR
determined that Schrader's speed was too fast and they decided to shrink
the restrictor plate down to 15/16 inches in time for the Spring race at
Talladega in 1989. The fastest speed turned with the 15/16 inch plate was Bill
Elliott's pole speed of 199.388mph at Talladega in May of 1990. This speed is also
the fastest pole speed since the dawn of restrictor plate racing. NASCAR, again,
made the restrictor plates smaller. For two races, the teams ran a 29/32 inch
plate, and then for the May 1991 Talladega race, NASCAR issued a smaller 7/8 inch
restrictor plate. The 7/8 inch plate stayed on the cars from May 1991 through
the 1995 season. In 1992, NASCAR made a rules change that dictated the minimum
spoiler angle. For the Daytona 500, the teams were required to run a minimum of 35
degrees, and for the 1992 July race at Daytona until October 2000, the teams
were required to run a minimum of 45 degrees. For the 1996 Daytona 500, NASCAR
lowered the compression ratio to 14:1 and opened the restrictor plates back to 29/32
inches. In 1998, NASCAR lowered the compression ratio again to 12.5:1. With
these rules, Joe Nemechek took the pole for the 1999 Winston 500 at Talladega with a
speed of 198.331mph. This speed became the second fastest pole speed
since the introduction of restrictor plates.
 NASCAR determined that the cars
were getting too fast and decided to take a new approach to slowing the cars down. For
the 2000 Daytona 500, NASCAR issued a 7/8 inch plate and also issued the front and
rear shocks the teams were to use. The teams were also required to run a minimum spring
rate of 345 pounds on the rear suspension. The spring rate is measured by
the force it takes to compress a spring one inch. In other words, it would
take 345 pounds of pressure to compress that particular spring one inch. Before
the spring and shock rule, the teams had been using soft springs and stiff
shocks to lower the rear end of the car to get the rear spoiler out of the
air, resulting in less drag and higher speeds. The new shock rule resulted
in a Daytona 500 that was pretty boring because the teams were not able to
make their cars handle properly. So, in response to the complaints from
the teams and fans, NASCAR did away with the requirement for the front shocks
after the Daytona 500. In September of 2000, NASCAR made a very unexpected
call. Because of the deaths of Adam Petty and Kenny Irwin, NASCAR issued restrictor
plates at New Hampshire. This was the first time that NASCAR had ever
issued them at a track other than Daytona and Talladega. Bobby Labonte took
the pole at 127.632mph, but the big shock of the weekend came when Jeff Burton took
the lead on the first lap and never gave it up, leading every lap on the way to victory. Many of
the teams, fans, and members of the media criticized NASCAR for making the wrong
decision.
A Winston Cup official
monitors the installation of restrictor plates at New Hampshire last
year. |
The 2000 season definitely saw many
changes to the face of restrictor plate racing. The most recent, and probably
the best, was the aerodynamic package introduced for the final restrictor
plate race of 2000 at Talladega. NASCAR's intentions were to cause greater drag, allowing
them to open up the restrictor plates and give the cars more throttle response. All cars
were required to run a 70 degree spoiler angle and have a lip across the top of
the spoiler that faced forward. The Fords and Pontiacs had to widen their
spoilers to 59 inches while the Chevrolets were allowed to keep their
spoilers 57 inches wide. The front air dam was raised to 4 inches to allow
more air to travel under the car. The most obvious change was the spoiler that was
installed on the roof of all the cars. It was set 10 inches back from the
windshield and was 1 3/8 inches tall by 40 inches wide. For qualifying,
the teams were issued a 1 inch restrictor plate and Joe Nemechek took the
pole at 190.279. The Saturday morning practice session was the first time that a
large group of cars were able to draft with the new aero changes. The fastest
practice speeds approached 198mph in the draft. NASCAR decided this was too fast and
issued the teams a 15/16 inch plate for Happy Hour and the race. The race was
absolutely incredible. There were 49 official lead changes, 21 different leaders, and
Dale Earnhardt's come from behind victory was simply amazing.
Restrictor plate racing has been
the source of some of NASCAR's most memorable and competitive races. It is
also sometimes the source of frightening races. "The Big One,"
a multi-car accident caused by the close packs of cars, is a direct result of plate racing and drafting. With
the cars so equal at Talladega and Daytona, one slip by a driver can wipe out half
the field. Restrictor plate racing has undergone many rules changes
since its induction in 1988. There have been eight changes in the size of
the plate, two compression ratio changes and multiple aero changes to the cars. Also,
the introduction of roof flaps has lowered the risk of the cars becoming air
born. In the future, it may be possible that NASCAR would do away with
the restrictor plates if the tracks and cars continue to become safer.
A special thanks to Jay of jayski.com for allowing me to use some of the information from his
restrictor plate chart.
The author can be contacted at contacts@autoracing1.com
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