With less than a year for development, chassis and engine manufacturers helped teams competing in the Indy Racing League (IRL) make history at the Indy 200 at Walt Disney World. The January race was the first Indy-style event to feature both new chassis and engines. Indianapolis Speedway owner Tony George’s vision of creating a racing league favoring young drivers with limited budgets competing on oval tracks has gained support from teams and fans.

This year’s Indy 500 will feature IRL teams for the second time, and spectators will see and hear many changes. Gone are the traditional CART (Champion Auto Racing Teams)-series open-wheel racecars; they have been replaced by chassis that emulate Formula One roadsters with air-induction tunnels, or airboxes, mounted high above the driver’s head. An airbox increases horsepower by forcing air into the engine compartment and is incorporated into existing roll hoop dimensions.

As for the engines, larger, normally aspirated 4.0-liter production V8s have replaced turbocharged 2.65-liter V8s. Instead of the high-pitched engine noise from the turboboosted engines, fans will enjoy the deep, throaty sound of Oldsmobile and Nissan power plants.

A Time for Change
New IRL rules focus on cost containment, safety, and equipment parity, and will remain in effect at least through 1999. To lower the financial hurdle teams face to compete in open-wheel racing, the IRL has put a $263,000 price limit on chassis ($220,000 for the chassis itself with the gearbox, fuel tank, and other accessories making up the difference), compared to CART designs that typically exceed $400,000. To cut costs, the IRL targeted the gearbox and bodywork aerodynamics. New specs include a standard six-speed, H-pattern gearbox made by Emco Gears Inc., Chicago, and the absence of aerodynamic appendages such as vortex generators on the underbody or outboard wings. These changes alone have cut team expenses for chassis in half.

While most of the Indy-style car dimensions remain the same, larger engines led to chassis modifications on the engine cover, airbox, engine mounts, and fuel cell. The chassis retains a ground-effects carbon-fiber/ composite monocoque or tub with the engine serving as an integral component or stressed member. Overall dimensions are similar to CART cars at 190 to 195-in. long and 78.5-in. wide, yet wheelbases have increased as much as 9 in. up to 118 in., and the height of the cars has grown to 37 in., a 5-in. increase.

The sanctioning body used the chassis redesign to improve safety as well as driver comfort. The chassis tub — the main section of the chassis between the front and rear axles — was widened 3 in. both internally and externally. Tub interior now measures 14-in. wide, corresponding to an exterior increase in width to 19 in. The nose cone and foot box also grew in length, providing more room for drivers’ legs and feet and letting them curl up their legs in event of a crash.

In the absence of underbody aerodynamics, drivers will rely more on the front and rear wings for track-hugging downforce. Front-wing designs are controlled by chassis manufacturers. The rear wing has a slightly longer cord length of 22 in. (measured from front to back) to accommodate aerodynamics around a taller engine cover.The IRL specifies two different tail wings, one for short ovals such as Phoenix International Raceway and the other for super speedways such as Indianapolis Motor Speedway.

Cost savings are also being realized by having teams buy chassis direct from factories, eliminating the distribution process. The field at this year’s Indy 500 will include chassis from two manufacturers — G Force Precision Engineering Ltd., Fontwell, Sussex, England, and Dallara Automobili da Competizione, Varano Melegari, Parma, Italy. An Indianapolis-based manufacturer, Riley & Scott Inc., will join the field in June, when the IRL will open competition to other chassis makers as well.

With such a short amount of time to develop chassis, the IRL set guidelines to avoid loose interpretation by designers. Dallara relied on computer simulations using software by Mechanical Dynamics Inc., Ann Arbor, Mich., to meet the deadline. “We built a complete model, including aerodynamics, suspension, transmission, steering, dampers, and a driver model. The computer then ran the model under racelike conditions using data from past races,” adds Andrea Toso, program manager at Dallara. “One complete lap takes 30 min, and the simulation gave us all the loads, speeds, and deformations used to modify our design prior to running it in our wind tunnel.”

Another chassis change prompted by the new engines is a relocated fuel vent and air socket for onboard jacking systems. “On previous turbocharged Indy-style cars, the engine cover was low enough to incorporate these components behind the roll hoop. Now the airbox occupies this space over the fuel cell, so we relocated these couplings on the left side of the monocoque,” says James Morton, co-owner of G Force.

The most noticeable difference between the English and Italian chassis is the sidepods on the G Force chassis that lead air exiting the sidepod-mounted radiators along the gearbox compared to Dallara’s aggressively raked deflectors that channel air over the rear tires to reduce drag.

During the chassis design and development, it was difficult for manufacturers to calculate overall weight because gearbox and engine manufacturers hadn’t established their final weights. There was a marked difference between the two chassis designs once completed. G Force came close to the 1550-lb minimum weight, while Dallara’s chassis weighed between 1,660 and 1,670 lb.

Though teams can’t change equipment suppliers, they can modify parts at their own discretion. Dallara’s Toso explains, “To trim weight, we suggested that teams machine excess material from gearboxes, rotors, and underwings, keeping within IRL rules.”

The IRL helped by increasing the minimum-weight requirement to 1,620 lb. This forced teams with G Force chassis to add weight to the cars. Though their cars were optimized at 1,550 lb, adding 70 lb didn’t have a deleterious effect on designs. G Force’s James Morton explains, “Adding ballast to the car isn’t bad when you have control over where it goes. We placed it low to the ground and used it to balance the car.”

Ditchin' the Turbo
The big changes under the hood, or more correctly the cover, are the productionbased 4.0-liter, V8 engines supplied by Oldsmobile and Nissan. Oldsmobile bases its IRL entry on the Aurora 4.0-liter V8 while Nissan modified its Q45 4.1-liter V8. The engines are normally aspirated, eliminating turbochargers, wastegates, pop-off valves, and special headers. It was necessary to modify the block because, unlike production vehicles, the engine in IRL race cars is a stressed member in the chassis.

The IRL also slashed costs by letting each team own its engines, replacing typical leasing programs that didn’t allow teams to even open engines for servicing. With a price tag of $75,000, they represent a considerable savings over their CART counterparts — turbocharged 2.65-liter V8s that cost nearly 1.5 million dollars annually to lease. The teams employ independent engine builders to assemble the engines and then use their own personnel for maintenance and repair. The IRL estimates teams will cut engine budgets by one-half to two-thirds, even if they own five engines. In addition, teams are free to sell engines to the after market at the end of the season.

Having only two engines to chose from also increases competition. “In the past, cutting a good deal on your engine lease or getting the latest version of a manufacturer’s engine gave a few teams a technical advantage,” says Scott Sharp, co-winner of last year’s IRL series.

The key to reducing engine-development costs was avoiding such practices as reducing the physical size and weight of the engine while increasing rpm. IRL regulations specify the minimum deck height — the distance from the centerline of the crankshaft to the head gaskets — at 8.1 in., 4.5-in. minimum crankshaft-to-sump dimension, 3.66-in. maximum cylinder-bore diameter, and a maximum engine speed of 10,500 rpm. Porting and polishing are permitted on cylinder heads, but original valve angles along with spacing, port locations, spark plugs, and camshafts must be maintained.

Since IRL rules don’t require pure stock engine blocks, Oldsmobile and GM Motorsports redesigned parts of the Aurora Indy V8, including the aluminum block and sump assembly, cylinder heads, and covers for the dual-overhead cams and camshaft drives. Oldsmobile shaved 0.74 in. off its block to get the most from the IRL minimum, letting it lower the car’s center of gravity. Nissan’s production engine has an 8.675-in. deck height, but the company chooses not to match the minimum due to performance trade-offs.

While rules require that engine makers stick with existing bore centers and camshaft drive systems, cylinders can be bored to a maximum of 3.66 in. and the stroke may also be adjusted. To get the most performance, both manufacturers are using the maximum 3.66-in. bore (the Infiniti engine is already there), and Nissan runs with a 2.898-in. stroke while Oldsmobile uses 2.890 in. The result for both engines will be compression ratios between 13 and 15 to 1.

On Track
With larger displacement, four valves per cylinder, and double-overhead cams, IRL engines produce 650 to 700 hp from an engine originally designed to produce 250 to 266 hp. Electronic rev limiters take away 3,000 revs compared to CART engines, which translates to an 8-mph decline in lap speeds.

One reason for slower engines is to make it safer for chassis that don’t sport expensive aerodynamics to create downforce. The IRL also hopes slower speeds will make finishes closer and bring out the talent of drivers to win races rather than have deeppocket owners outspend the other teams with expensive development programs.

The IRL feels rules are restrictive enough so that no amount of money will give teams a decisive edge. While there will be differences in horsepower, the goal is to limit this range so that skillful drivers and talented crews can make up any deficiency by maximizing handling, tires, and the racecar’s aerodynamics.

With such a short amount of time to develop the new racecars, teams had less opportunity to work the kinks out of new chassis and engine combinations. Arie Luyendyk was the first to test the new setups, using his G Force/Oldsmobile Aurora racecar in mid-November. Eliseo Salazar followed by testing his Olds-powered Dallara chassis in late November. The rest of the teams had to wait until Dec. 10 to test engines and chassis in preparation for the Indy 200. Teams had just over six weeks to prepare for the Jan. 25 race.

Reports from the track were promising and positive for the future of the IRL. Scott Sharp, racing a G Force chassis powered by an Aurora engine for A.J. Foyt Enterprises, says, “The cars are more drivable. With the downforce coming from the wings rather than underbody aerodynamics, cars are more predictable. The new designs let drivers push them to the limit with confidence. You can lean on the car by driving it into the corner. In the past, you had to be more tentative. Older cars had a narrow window of comfort, and it was easy to slip on one side or the other.”

Tony Stewart, racing for Team Menard Inc., another Oldsmobile-powered G Force chassis, adds, “The throttle response is different without turbos, and handling characteristics differ slightly. Compared to last year, I’m on the throttle a lot more and drive more aggressively.”

Eddie Cheever Jr. won the first race with the new chassis and engines at Walt Disney World in Orlando. Jim Guthrie followed with a win at Phoenix on Mar. 23. The IRL has achieved its goal of increased competition so far, with seven different winners in seven races (including last season). The league hopes the new chassis and engine set-ups will continue this trend.

Cheever, a Formula One and Indy car veteran, adds, “Racers now don’t have to be intimidated by the size of other teams. Though the best-funded teams will have more equipment at their disposal, the gap between them and the have-nots is not impossible to overcome, as we proved at Disney and Jim Guthrie showed at Phoenix. Drivers aren’t restricted just because they don’t have big budgets or large-company funding.”

With just two races under their belts, teams continue to deal with the usual adjustments and modifications necessary to tweak performance from the new racecar designs. Reliability continues to be a concern for teams, with a combined twelve racers unable to complete the first two races due to equipment problems, not counting mechanical failures that caused mishaps such as oil leaks.

“It’s difficult to point a finger to one area of a racecar and say that’s the problem. Everything is tied together, like a person’s health: your immune system has to be working for other bodily functions to work,” says Cheever. “It’s unfair to say its all the engine’s problem. Some cars didn’t finish races because pieces were falling off. We had a self-induced problem in Phoenix that wasn’t the engine. The engine ultimately failed but as a result of other complications.”

Engine manufacturers continue to improve performance as well. “Our development team is working on the normal reliability issues that come up during extended track and dynamometer testing,” says Joe Negri, GM Motorsports IRL and road-racing group manager. “We have had some engine failures, but that is to be expected when testing a new engine. A 4.0-liter engine running at 10,500 rpm has the pistons moving 5,000 ft/min., which is higher than typical turbocharged 2.65- liter engines. These conditions are very demanding on engine parts.”

With only two companies supplying engines, they have received a lot of feedback from teams in a very short time. This will help the league work out design concerns more quickly and modify specifications if necessary. With so many components being developed at the same time, no rules are set in stone. The IRL realizes it must be flexible to accommodate the needs of the drivers, teams, and equipment manufacturers.

The racers are optimistic about getting the cars tuned in by Memorial Day weekend. As for the speed differences to expect at the Indy 500, Leo Mehl, Indianapolis Motor Speedway vice president and executive director of the IRL, says, “Preliminary testing at the track in March met our predictions. The cars ran approximately 20 mph slower in corners and about 25 mph slower on the straightaways. Race speed should be between 210 and 215 mph.”

Though there may not be any speed records set this year, the race itself may be more exciting. “We can run the cars closer together because they put off less turbulence than older designs,” adds Scott Sharp. This is in synch with the IRL’s goal of giving each team an equal chance of winning at Indy-style racing. This is good news for the fans, too, who will reap added visual and audible excitement from the new racecars.

Tread wars
Because of new chassis and engines, Goodyear and Firestone — the two IRL tire manufacturers — were forced to modify existing designs. Engineers ran computer simulations accounting for aerodynamics changes, a 10% reduction in speed due to horsepower decreases, different weight distribution, and new tracks.

Design teams relied on these simulations, since they also had to vie for track time while teams concentrated on tuning the engines and chassis. “Even with computer simulations using racing parameters, you still need track testing. You’ll never be able to replace driver feedback with software. Each driver has his own style, plus you have to keep up with chassis and engine changes,” explains Don Vera, manager of product development for race tires at Goodyear, Akron, Ohio.

Racing tires consist of composites made from fabrics and fibers such as Kevlar, natural or synthetic rubber, carbon black filler that boosts strength, oils to keep the composite together and add traction, curatives that cross-link or vulcanize the rubber, and accelerators that control the speed of this reaction. Both suppliers have gone to softer compounds with more grip or traction and made adjustments to handle the difference in speeds and operating temperatures.

However, the change is not as significant as it may seem. “A 10% change in speed causes more of a design revision than it does a total redesign starting from a clean sheet of paper,” explains Al Speyer, director of Firestone motorsports, Nashville. “The 50-mph difference in top speeds between the two types of ovals is a greater challenge than the 20-mph drop in speed that we will see at the Indy 500.”

Firestone will use a combination of new materials and computer technologies to design IRL tires. The technology, called UNI-T (Ultimate Network of Intelligent Tire), consists of three elements: computer-optimized component system (CO-CS), L.L. carbon, and O-Bead. The CO-CS system is software that performs cyclic calculations and optimizes designs using parameters such as tread design, casing shape, materials, and construction.

L.L. carbon, or long-link carbon, is a reinforced form of carbon black that increases wear resistance, grip, and consistency over tire life. It helps reduce the traditional trade-offs between grip and wear. Conventional carbonblack particles form clusters that look like bunches of grapes. L.L. carbon replaces these clusters with long chains that resist wear by dissipating crack energy over a larger area, thereby increasing tread life.

O-Bead changes the way the tire bead — a cable that runs through the sidewall — holds onto the rim. On most tires, the cable overlaps where its ends meet. This leads to an oblong shape which creates tiny gaps where the tire lip meets the rim. O-Bead eliminates the overlapped joint by using a continuous strand of cable. A precisely round bead with better fit improves handling response. It also reduces high-frequency-vibration energy losses in the tires at high speeds. With greater roundness, tires drive more efficiently on straightaways and are stable and consistent in turns, eliminating steering shake.

The focus at Goodyear is to achieve good balance between front and rear tires. “Initially, there was a question

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