Before The Car Of Tomorrow
Though plans are tentative, NASCAR plans to debut a Nationwide Series (Busch until 2008) "Car of Tomorrow" (COT) by 2010. The body and aerodynamic package will be different than the Sprint Cup Series cars. The Nationwide COT will have important differences from the Sprint Cup COT, and the current Nationwide car. The Nationwide COT will share a chassis with the Sprint Cup COT, but not a body. Because of this, the wheelbase will be extended to 110 inches. The body will be different from the Sprint Cup COT to differentiate it.
Before the Car of Tomorrow, NASCAR officials established strict rules about the size and specifications of a legal racing engine. When NASCAR teams race on the Daytona International Speedway or the Talladega Superspeedway - the two biggest tracks in the Sprint Cup Series - engines need to be fitted with a restrictor plate to cut airflow to the engine to put a cap on racing speeds.
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 c.i. (bore x bore x 0.07854 x stroke x 8) and 12:1 compression: compression is the reduction in volume and an increase of pressure of the air/fuel mixture in the cylinder before it's ignited by the spark plug. It's produced by the motion of the piston as it travels up toward the engine's cylinder head — after the air/fuel mixture enters the cylinder. A compression ratio is a ratio of the cylinder volume enclosed by the piston at its outermost position (top) to the volume enclosed by it at its innermost position (bottom).
But for various tracks the torque output is tailored by variations in bore and stroke ratio (engine bore is the inside diameter of the cylinder and stroke is the amount of distance the piston travels in the cylinder from top to bottom or vice versa) to get the performance combination for acceleration off the turns or straightaway speed as desired by the particular driver/team preference. Since many teams were running 17.5-18:1 compression at non restrictor-plate tracks, less horsepower means less speed, but it doesn't necessarily reduce throttle response, a major criticism of the dreaded restrictor plate.
Restrictor plates are aluminum with four 29/32 inch holes. They are placed between the carburetor and intake manifold on an engine. The carburetors used in Winston Cup have four 1 9/16 inch diameter barrels. When this 29/32 inch restrictor plate is installed, the air-flow into the engine is restricted, thus reducing horsepower. Restrictor plates were mandated on Winston Cup 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 1988 season. The original plates had 1 inch holes. Now, they're down to 29/32 inch. The advent of the flaps (full operational air deflectors), used to keep a car from going airborne once it starts to travel backwards, has almost made the restrictor plates unnecessary. But because of Irvan's 1994 accident at Michigan, these are unlikely to be disappearing any time soon. Speed is the only thing fading.
Most shops buy their frames prefabricated from a frame supplier. The frame consists of a structure of round and square steel tubing of varying thickness. The bulk of the structure surrounds the driver. This part of the frame — the roll cage — is made of the thickest tubing and is designed to stay together, protecting the driver during any type of crash.
The front and rear sections of the frame, called the front clip and the rear clip, are built from thinner steel tubing so that they will crush when the car hits another car or a wall. In addition to being collapsible, the front clip is designed to push the engine out of the bottom of the car — rather than into the driver's compartment — during an accident.
When the frame comes into the shop, the firewall (the metal panel separating the engine compartment from the driver's compartment) and floor panels are welded in, along with various mounting brackets for things like the engine, suspension, seat, fuel cell and body.
Busch and Winston Cup bodies are both based on American-made full-size passenger cars and have to look at least something like the cars we drive on the streets. Both divisions also have to abide by NASCAR's "three-year" rule. That means that no car body can be more than three model years old.
The process of making the body for a NASCAR race car is incredibly labor-intensive. The shape of the car is mostly determined by NASCAR rules. These rules are encapsulated in a set of 30 templates, each shaped to fit a different contour of the car.
For instance, the biggest template fits over the center of the car from front to back. When the template is laid on the car, the gap between the template and the car cannot exceed the specified tolerance. Each template is marked on its edge with a colored line. If the line is red, then the gap must be less than 0.07 inches (0.18 cm). If the line is blue, the gap must be less than 0.25 inches (0.64 cm). If the line is green, the gap must be less than 0.5 inches (1.27 cm). The templates actually allow a little leeway in the design of the car. Because 30 templates are not enough to cover every inch of the body, some areas between template locations are not strictly controlled by NASCAR.
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 hoods, roofs, and trunk lids come from the auto manufacturers, and the "floor pans" (floorboards) are stamped from an original mold and are provided by suppliers. The bumpers can come either from the manufacturer or an "aftermarket" supplier.
All other sheet metal (no fiberglass, aluminum or exotic stuff like titanium's allowed) pieces are created by race team fabricators. The plastic nose and tail bumper covers are after market parts but the remainder of the body panels are made by trimming and then hand-rolling flat sheet metal between the rollers of an English wheel, which slowly bends and curves the metal for the fenders, doors and quarter panels until the contour matches the templates and fits on the car.
After the pieces are shaped, they are welded to the car and to each other, using the templates to check their location. The seams between pieces are welded and then ground down so that when the car is finished, it is one smooth, seamless piece. The doors don't even open.
After the car body is installed and ground smooth, the car is primed and painted. All of the decals are installed, including headlight decals (NASCAR cars don't have headlights), which helps make the race car look more like a street car.
According to the Winston Cup Rules Digest in Winston Cup Scene, Winston Cup cars must follow these guidelines (NASCAR issues different Rule Books, each of which includes in its title reference to a particular NASCAR-sanctioned series.)
The cars in both divisions 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. In October 1996, ground clearance was increased for both Chevy and Pontiac. Decklid spoiler height was decreased for Chevy and Pontiac and increased for Ford. In its struggle to promote even competition, NASCAR will continue to fiddle with the spoiler sizes, air-dam clearances, roof heights and other body dimensions. Fine-tuning????? of each model will of course continue until every car on the track looks alike.
The location of the fuel cell has been standardized within a 4-inch range along with a standard size and location for the instrument panel and a maximum height for the roll cage. What's underneath a race car's "skin" in no way resembles what you drive. The frame, or chassis, is composed of heavy-duty steel frame rails, and the system of hoops, loops and bars that make up the roll cage assembly is custom designed for strength. This allows the chassis to be built independent of whatever bodywork will be hung on it --- Ford, Chevy or Pontiac.
Windshields also have to be stock, or as NASCAR puts it, "standard production laminated glass or hard-coated polycarbonate windshields with a minimum one-quarter-inch thickness." It, however, is OK to install an eighth-inch-thick polycarbonate (plastic) windshield under the true windshield inside the car. This second windshield is for added protection and is supposed to keep foreign objects that might hit the glass windshield from coming into the driver's compartment.
The rear window has to be in place, but it's plastic and not glass. Also, for tracks bigger than 1.5 miles, a full, one-piece window has to be in place on the car's right side. That's to keep air at high speeds from rushing through the car and making it unstable to the point where it could flip over. Otherwise, door windows aren't permitted, but a "nylon mesh window screen must be installed on the left-side door glass opening."
There is a 3,400-pound minimum vehicle weight. The minimum is 1,600 pounds on the right side for oval tracks or a minimum of 1,600 pounds on either side at road courses. Add a 200-pound base driver weight, essentialy creating a minimum weight for vehicle and driver of 3,600 pounds. Adding the drivers' weight to the minimum means that the car must still weigh a minimum of 3,400 pounds, making the lighter drivers carry additional weight to reach the 3,600-pound minimum for car and driver. If a driver weighs 155 pounds, he will have to carry 50 pounds of additional weight. Trickle weighs about 185 pounds.
The driver with the fastest qualifying speed selects his pit space first. Most will choose the first pit stall, the one closest to the white line at the exit of pit road, in order to have a drivers position exiting the pits. The rest of the drivers choose pits based on the order in which they qualified for a race.
On tracks that are more than 1 mile (1.6 km) long, where speeds are faster, NASCAR rules require that tires contain an inner liner. This is essentially a second tire mounted inside the first tire. It mounts to the rim and has its own separate air supply. If the outer tire blows, the inner tire is still intact, allowing the driver to bring the car to a controlled stop.
NASCAR regulates which tire compounds are used on each track. The tire compound is the material the tire is made from — a softer compound can provide more grip but wears faster, while a harder compound will last longer. Each track causes tires to wear differently, and the inside tires wear differently than the outside tires. Track surface, number of turns, tightness of turns and type of banking are all factors that determine how a tire will wear. Since tires are so critical for safety, NASCAR and driversyear have determined the best compounds for the inside and outside tires for each track, and these are the tire compounds that the teams are required to use.
To save a bit of money, Cup teams are restricted to using only three sets (4 tires) for practice and qualifying. A fourth set is allowed for teams who run in second-round qualifying. Additionally, NASCAR has the right to inspect and impound all tires and wheels, and cars in both Busch and Winston Cup must start the race on the tires they used in qualifying.
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