The "official" NASCAR rules and regulations are not made available to the general public or to the media. NASCAR reserves the right to disseminate those regulations only to those teams it deems of merit as seriously contending participants.
The Winston Cup (WC) series used to be known as Grand National. The name was changed in 1970 to the Winston Cup Grand National Series, and then in 1986 to simply the Winston Cup Series. Busch Grand National (BGN) now refers to the NASCAR series which is the main feeder series for Winston Cup. The Busch sponsorship started in 1985. The series was formerly known as the "Sportsman Division" from 1950 to 1967, then "Late Model Sportsman Division" from 1968 to 1982. Budweiser sponsored the series from 1982 to 1985. Winston Cup is considered the premier series in NASCAR. There are a lot of WC drivers who double-up between the two series, but BGN is sort of a "lesser major league," somewhat akin to relationship of the former World League to the NFL in American football or of the IHL to the NHL in ice hockey.
The Busch Series originally ran mainly on short tracks, tracks less than a mile in length, but as they were eventually made companion races to Winston Cup events, they now run on more speedways than short tracks. Busch Series races cover shorter distances, while the Winston Cup series race lengths are longer and are increasingly set to durations that satisfy TV time slots. The Busch Series has picked up a few superspeedways in the last few years, such as the Homestead Motorsports Complex, Texas Motor Speedway, The California Speedway, Gateway Speedway, The Las Vegas Speedway and Pikes Peak International Speedway.
There are some differences between WC and BGN cars, but they are being made more similar. In 1997 the Busch series used 358 cid V-8 engines with 9.5:1 compression ratios. The 9.5:1 compression engine is also the power plant for the NASCAR Craftsman Truck series. The 9.5:1 is supposed to be more reliable and cheaper to maintain than the high compression engines that are currently in use (especially at the superspeedways). In 1997, the Winston Cup series engines had a 14:1 compression ratio for all races. In 1998, the ratio was reduced to 12:1 in Winston Cup.
Secondly, the BGN car weight has been increased to 3300 lbs, and the WC cars have decreased to 3400 lbs. The story here is it is currently a big jump going from a BGN car to a WC car. This weight shift is supposed to make the transition from BGN to WC easier. Beginning in 1997, the weight of the driver is included in the 3400 lb. weight of the car - which may be an incredible advantage to drivers who are light (put any differential dead weight where it'll help the chassis). Wheel bases are 110 inches for WC and 105 for BGN.
Cars are also required to have nylon mesh screens in the driver's side door window opening and many have adopted the use of a second, triangular net to contain the head during side impacts. Windshields are made of Lexan and many use a "tear-off" on the driver's side. The rear windows are also Lexan and at tracks of less than one and a half miles in length, the right side door window is left open.
NASCAR Winston Cup engines today generally use pistons manufactured by J&E, Wiseco, Ross and a couple of others. There are usually very few "Factory" (i.e. Ford or Chevy) parts used in/on the entire car, although quite a few of the engine components are from the manufacturers. For most parts, any supplier could be used - even Mercedes-produced pistons could be used in either a Ford or Chevy given the correct bore diameter and wrist pin placement, rod length and crankshaft stroke.
The engine block and head castings are usually bought in rough form to conform to the casting number rules required by NASCAR. The blocks are special alloy materials, such as higher than normal tin content and extra webbing area for strength around the main bearings. The heads are aluminum alloy and also much different than any production heads. Extra material is generally available for various teams to port them in different ways and to bore the valve guides just the way they want them. The engines also are always 358 cid, but for various tracks the torque output is tailored by variations in bore and stroke ratio to get the performance combination for acceleration off the turns or straight-away speed as desired by the particular driver/team preference.
Many or most teams use the roof and windshield post sheet metal from factory production to obtain proper profile and height as these parts are difficult to form by hand. The plastic nose and tail bumper covers are after-market parts, but the remainder of the body is usually formed by hand using a tool called an "English wheel" which helps stretch and curve the metal for the fenders, doors and quarter panels.
According to the "Winston Cup Rules Digest" in Winston Cup Scene, WC cars must follow these guidelines: "The cars must be neat in appearance and the interior must be painted. The original exterior dimensions of all the bodies must remain as manufactured, except for changes that may be necessary for tire clearance. The body cannot be offset on the frame. Rocker and quarter panels cannot be notched for exhaust pipes. Cars must remain standard in appearance." Obviously, NASCAR retains the right to determine what "standard in appearance" means.
Beginning with the re-introduction of the Monte Carlo to replace the Lumina, and later, with the Taurus replacing the Thunderbird, NASCAR has more publicly made use of body "templates" for scrutiny and control of how teams build their cars. Rules changes pertaining to front spoiler clearance from the ground and the height/width of rear spoilers are made frequently, purportedly for safety and to level the playing field among car manufacturers.
They are aluminum plates with four 7/8 inch holes. They are placed between the carburetor and intake manifold on an engine. The carburetors used in WC have four 1-1/2 inch diameter barrels. When this 7/8 inch restrictor plate is installed, the air-flow into the engine is restricted, thus reducing horsepower. Restrictor plates were mandated on WC cars at Talladega and Daytona in 1988. NASCAR first attempted to slow speeds after Bobby Allison's car became airborne and crashed into the spectator fence at Talladega in May of 1987. NASCAR first tried smaller carburetors (for the July races at both tracks) but decided on the restrictor plate to begin the '88 season. The original plates had 1 inch holes. Now, they're down to 7/8 inch.
Officially, they are called "Fully Operational Air Deflectors". They were developed by Roush Racing to keep a car that is going backwards from becoming airborne, and keep the car down on the track or ground. The flaps are hinged to the roof and have a tapered edge where air coming forward from the back of the car can activate the flap. The flaps are tethered down by cables and a weight that hang loose inside the car. The cables keep the flaps from over-extending and not doing the job of keeping the car from going airborne.
The two flaps are set toward the rear of the car's roof, one parallel to the rear bumper and another angled toward the right rear corner. The theory in the placement is that few cars spin to the right, especially on the high banked tracks of the Winston Cup series. Two Cowl Flaps have also been developed.
Anyone who believes these flaps are 100-percent failsafe didn't see Ken Schrader's end-over-end tumble down the backstretch of Talladega. The cause of the crash was a common one in cases where flap-equipped cars end up flipping over: After getting spun by teammate Jeff Gordon, the leader of a train of cars bearing down on Schrader, Ricky Craven, smashed into his left rear end, forcing that side of the car down and the right side up at an angle. Before the flaps could deploy, the car was already airborne with tail-end nearly vertical. The flaps couldn't push the car down because the car was on its side. Momentum took care of the rest as the 25 car ended up in the infield, upside down with only the driver cage intact. (Schrader only suffered a black eye in the ordeal.)
The Schrader crash made it even more likely that there won't be a change in rules regarding the restrictor plate any time soon.
The big change at the end of the '97 season was the demise of the Ford Thunderbird. Ford initially dropped some suggestions that the Thunderbird would be discontinued by the end of the century. There was a large hue and cry about this, but Ford made the final decision. The Kranefuss-Haas team tested a Lincoln Mark VIII body style at Charlotte Motor Speedway back in May, but company executives declared that there would be no intra-corporation competition in stock car racing for Ford and they did shelve the Thunderbird (the winningest single model in NASCAR history) and replaced it with the first four-door in the modern era. The Penske team did the major development work on the Taurus prior to the '98 Daytona 500 and all Ford teams scrambled to get all their cars ready, hanging new body sheetmetal. Jack Rousch apparently won a battle with Robert Yates over certain details of body location/shape for the Taurus that put the Ford at some disadvantage on the restrictor plate tracks, but seemed to provide an advantage on the short and intermediate length tracks. NASCAR responded with the "5 and 5 spoiler rule" and later modified the Ford spoilers again.
For 1998, compression was set for Daytona and Talladega at 12:1, (or is that 12.0000:1.0000, after earlier, NASCAR had gone through much misery when they realized they needed the specification carried to more decimal places as a result of Rusty's Spring Richmond race result delay?).
Several rule changes occurred over the off season in 1996-97 regarding the mechanical side of competition. NASCAR put some specifics down in chassis construction standards (roll cage height, fuel cell location, components, etc.) and allowed a new forced-air "cold-air box" under the hood of the car. In its most controversial decision though, NASCAR mandated the raising of the rear quarter-panels of every car by one inch for races at Daytona and Talladega. Not only that, but the mandate also specifies that the car would have to meet the height restriction with a 75 pound weight hung over each rear wheel, to test the stiffness of the springs (to make sure the quarter-panels would stay at that height at race speeds). These two factors would slow a car down significantly, but that decrease is essentially negated by the cold-air box, which was allowed to gain more horsepower.
As always, NASCAR rule changes have continued whenever it is determined that changes are necessary. The Dupont team brought the "T-Rex" car to Charlotte for The Winston race in 1998 and it was dominant enough that they were 'invited' not to return with it for the Coca-Cola 600.
This page was last updated on June 11, 1999
