How NASCAR creates the closest racing on the planet

The 2011 NASCAR Sprint Cup Series rulebook is a small, pocket-size 166-page publication, which comprises 20 different sections. Most of them relate to the sporting regulations and only the last one enters the technical domain and is referred to as 'NASCAR Sprint Cup Series specifications'. However, it spreads through 117 pages, which equates to seventy per cent of the book.

Through hundreds of lines, the rules set dimensional limits for almost every component of the car. There's an index at the end of Section 20, where almost 200 items are listed, most of them specific parts that range from a ball-joint to an engine. Many have a specific part number from vendors who supply approved spoilers, carburettors, fuel cells, brake ducts or shock absorbers.

The wording of the rules goes as far as stating what the approved firing order for each engine must be, plus very precise numbers that set limits for the critical parts of the powertrain.

NASCAR's R&D centre

The NASCAR Research and Development group, which works out of a purpose-built facility in Concord, North Carolina, has a very tough job setting this tight set of rules that lay the foundations for the ultra-competitive racing that takes place almost every weekend. Around 58 people, 18 of them based full-time on the R&D facility, work on the safety, competition and cost-management aspects that are summed up by the series' rulebook.

The building, which opened in 2003, is strategically placed within a few miles from most of the teams' bases and it's just a five-minute drive from Charlotte Motor Speedway.

The main technical development that has come out of the 61,000-square feet facility has been the current specification of Sprint Cup car, which hit the track in 2007, setting new standards for NASCAR's top-level series in different areas.

Notably, the design of the car enhanced safety for the drivers, while also proving successful from a competition standpoint. Statistics for lead changes and different race winners are the proof. The car, which already has its equivalent in the second-tier Nationwide Series, limits teams' ability to alter bodywork, thanks in part to tougher checks being implemented before its arrival.

On the previous generation of Cup car, you would see bodies being completely asymmetrical and twisted out of shape. They certainly didn't look right, but that was the result of teams experimenting in windtunnels while looking at optimising aerodynamic performance depending on which track they visited.

For Talladega, teams aimed at reducing drag, while for Charlotte or Texas the target was maximising downforce. Some of that still lingers, but to a much lesser extent with the 'Car of Today' - as it is now called.

"When you talk to the crew chiefs they'll tell you that with this car the window of adjustment you have is smaller," says Mike Fisher, an engineer with more than 16 years' experience in the auto industry, who has been managing director of NASCAR's Research and Development since 2006.

"The car is more sensitive to adjustments and not as tolerant to bad adjustments. So it's more about how well the crew chief can set up that car to match the driver on that particular day and how well he can drive through a car that maybe isn't perfect. That's part of the competitiveness we want to create while trying to demonstrate the skill of the driver as well."

Between six and eight chassis (including Sprint Cup and Nationwide) go through the R&D facility daily in order to be certified before they are built up to a race-ready condition.

The process uses state-of-the-art technology to measure between 60 and 70 different points in the frames, including dimensional checks, performed with laser technology on a steel platform through an articulating arm. Metal thickness is also verified through ultrasound, with different tolerances set for every measurement.

An inspection typically takes around 90 minutes to be completed and if all goes well, 11 radio-frequency tags are placed in key points of the chassis in order to prevent any future alteration. If tolerances are not met initially, checks take place all over again once the team has made the requested adjustments. If a chassis returns to the R&D centre following a successful race, the seals have to match the records from this initial certification process. If they don't, the team will have some explaining to do.

The basic structure of the central part of the chassis is unique, while freedom for the team's engineers is given on the front and rear clips where engine and suspension are mounted. Those are the areas where chassis differ more from one team to another, from one type of racetrack to another.

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As with every category of motorsport in the world, NASCAR focuses heavily on keeping costs under control. Indeed, part of the reasoning behind the current car when it was conceived was that teams wouldn't need to build as many as before - given that the rules would prohibit making a chassis too different from another.

Through experience, however, competitors have found ways to make cars that are better tailored to certain conditions, although some teams have been able to add more versatility to their chassis. This in turn brings down the number they use over a season without hindering their performance.

"Really what we try to do through this certification process is make the cars common enough so that they don't need to have a specific vehicle for a specific racetrack," Fisher says.

"You'll still have superspeedway cars, road-course cars that are special, but because we can read every chassis and know where each car has been raced previously and how many times they've been inspected, we've been able to see chassis that have raced at Martinsville and then done a test at Talladega. We've seen cars raced at both Dover and Michigan, which was unheard of with the old chassis."

With four different manufacturers - Chevrolet, Dodge, Ford and Toyota - competing in NASCAR's top series, a need for brand identity on the cars is high on the list of demands. Although cars may look different thanks to the decals for front grille, head- and tail-lights, there's variation in the shape of the nose and the hood and NASCAR has to ensure that while they differ visually, the downforce and drag levels are evenly matched for all four.

To do that, a full-size car runs in the nearby Windshear windtunnel with the different hoods and noses, to get those numbers as close to target as possible. Some differences are also allowed on the shape of the grill opening that feeds the radiator on the lower part of the nose, while brake-duct openings are the same for everyone.

Although the new Nationwide car goes way beyond the gaps seen on Cup racers from one brand to another, that is likely to change in 2013 when new bodies will be in place for NASCAR's top series' cars so that brands get a better identity on the track.

The chassis certification process is strict and rigorous, with the bodywork inspection equally so. Before the new Cup car came in full swing, templates used on 'tech' at the track during events used to be two-dimensional, which meant they measured shape but not location, allowing sculpturing on the sheet metal bodywork, as seen on the previous generation of cars.

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Now, most of the templates have been combined and are referred to as the inspection grid or 'the claw', a huge metal structure in which the car has to fit on every area - from the roof down to the bumpers.

Two-dimensional templates are still used to measure the shape of the upper part of the car from nose-to-tail and one of them, known as the F3 template, has mandated tolerances as small as 0.125 inches.

Teams will play as much as they can with those tolerances and it's not uncommon to see mechanics trying to pull out the part of the right rear fender just ahead of the rear wheel in an effort to trim the car's aero a bit. In order to prevent that, NASCAR placed a reinforcement piece to restrict re-shaping of the lower part of the bumper.

A similar thing happened with the alignment of the rear axle, which got extreme a couple of years ago. Crew chiefs yawed the car in order to increase the amount of air getting to the right part of the rear wing [now a spoiler] but the cars looked like they were running sideways on the straights as the rear wheels were offset with the fronts. NASCAR quickly drew the line to avoid those wild asymmetries developing further.

"The inspectors start to see trends with the teams and if they see things that they have questions about they'll call our competition people and ask to have a look at it," says Fisher.

"They'll see it and talk to the crew chief and decide whether it's acceptable or not as a first line of defence. If we don't do that, within two weeks everybody will have it and it would become a hassle to outlaw.

"Teams are very creative. They'll find the areas where we haven't made rules and if they find something that's to their advantage, they will use it."

From an aerodynamic standpoint, there isn't a lot teams can do to make a difference, but they will go as far as they can with their windtunnel and CFD programmes to find the tiniest possible gain. When 30 or more cars rank within half a second at the aero-dependent, mile-and-a-half tracks, then anything you can find over your rivals will move you up in the pecking order.

Teams can also play with the wind as a means to help cool brakes and tyres, aided by electric blowers. However, the way that air is routed through the car is closely checked by officials to prevent any attempts to drag out air from underneath in a bid to generate more downforce.

The work done by the R&D people extends beyond their facility and onto the race track, where cars are inspected three times - on the opening day (the equivalent of Thursday scrutineering in Formula 1), before or after qualifying and before the race.

Besides that, a further inspection takes place for the top finishers once the race is completed. The winning car, for example, is escorted by officials from Victory Lane down to their garage stall where a list of items that have to be removed is handed to the team, so that the car is ready for a more detailed post-race inspection at the R&D centre.

Sometimes even before the car gets to Victory Lane, it is clear that the body or even the chassis has been modified due to damage, making a post-race inspection hard to perform under the normal parameters. Take Carl Edwards and his post-race celebration in the recent All-Star race at Charlotte as an example. He spun his car along the infield grass and ended up damaging the front end after hitting a dip.

Carl Edwards managed to wreck his car while celebrating All-Star victory © LAT

Conspiracy theorists pointed at a blatant attempt to make his car impossible to inspect after he had won more than $1million in prize money from the event, but at the same time he ruined a car that he may well have raced at the same track a week later in the Coke 600.

"We've had times when we have had to tell teams that it's fine to spin the car around, and that type of thing, but don't push it up against anything, don't climb out and jump on the roof'," Fisher says.

"We have some post-race guidelines for the teams, so they know what they can and can't do from a celebration standpoint. At superspeedways, guys would climb out of the cars and jump up and down so that they'd dent the roof."

After every race at least two cars - the winner and one random choice - are taken to the NASCAR R&D centre. In addition, the engine from the second-placed car is also impounded, along with the first car to retire for reasons other than an accident. Sometimes, low-budget entrants qualify and then pull out of the race, claiming the prize money. NASCAR is keen to ensure that they do so legitimately.

The day after the race, impounded engines are torn down and measured, while the post-race chassis inspection takes place. NASCAR also has the ability to check power outputs, using its water-brake dyno. At the track, the authorities can test cars on a chassis dyno to verify that engines are as evenly matched as possible. Although power curves may differ - some manufacturers have different engine builders - maximum output figures tend to be reasonably close.

"We try to keep engines as close as we can," says Fisher. "Our goal is to have them all be identical, however that's pretty challenging. When there's a difference from the best of each manufacturer approaching 15bhp we start looking at it. We'll look at the rules and the pieces that they've submitted to see if there's anything we can do."

Very rarely do issues come out of post-race engine inspections, but three years ago NASCAR mandated a restriction on Toyota engines as they dominated the Nationwide Series with Joe Gibbs Racing. Chassis dyno tests showed more than a 15bhp advantage, which led to an adjustment in air intake through a larger restricting spacer for the carburettor compared to other cars.

Clearly, it's key for the sanctioning body to be able to police every key parameter of performance so that it can maintain an even-playing field.

It took many years before NASCAR was able to get the right partner in place to make the expected switch to fuel injection, but McLaren Electronics ticked all the boxes last year and it promises to provide a cheat-proof system that will help make a smooth transition in 2012.

In an already complex set of regulations, fuel injection will certainly add another layer of policing, which NASCAR's Research and Development group has been working on for some time.

It is their job to ensure that America's most popular form of motorsport continues to move forward while living up to its claim of putting on the most competitive racing possible every weekend.