CHAMPCAR/CART: Mercedes Pursuit of Peak Performance

Simulation and the Silver Arrows Technology Proliferates in Pursuit of Peak Performance MONTVALE, N.J. (July 1, 1999) -- As the competition for the checkered flag gets tougher in the CART FedEx Championship Series, the...

Simulation and the Silver Arrows Technology Proliferates in Pursuit of Peak Performance

MONTVALE, N.J. (July 1, 1999) -- As the competition for the checkered flag gets tougher in the CART FedEx Championship Series, the ability to simulate racing conditions to test a race package becomes a critical part of a successful program.

While Mercedes-Benz provides its IC108E Phase III (E3) engine to five teams fielding eight Champ Cars in CART, each team makes individual choices about which chassis it will race, and how it will develop the package for competition. Mercedes-Benz relies on sophisticated dynamometers ("dynos") at its headquarters in Stuttgart, Germany, and at the Ilmor Technology Center in Plymouth, Mich., to perfect the power and efficiency of the E3 engine. And while manufacturers of Mercedes-powered Champ Cars might have different philosophies about race car design, they work closely with Mercedes engineers in an effort to put the most competitive car possible on the grid.

Chassis builders possess their own growing arsenal of technology, from computer-aided simulations to wind tunnels. In fact, only hours after completion of the Texaco/Havoline 200 at Elkhart Lake, Wis., Lola Cars International -- which supplies its new B99/00 Champ Car to Hogan Racing and Marlboro Team Penske -- will unveil its new seven-post dynamic test rig at its facility in Cambridgeshire, England.

Reynard Motorsport, chassis supplier to PacWest Racing, Player's/Forsythe Racing and Bettenhausen Motorsports, also employs high-tech simulation at its facilities in Shrivenham, England, and Indianapolis. The company's new Auto Research Center features a 50-percent-scale, open-jet/rolling-road wind tunnel and a seven-post dynamic test rig. Reynard's fluid dynamics research complements their aerodynamic data acquisition by allowing analyses of internal flows -- for example, within braking systems and fuel tanks -- and by providing thermal studies of engine cooling and exhaust gases.

"Certainly our fans identify with the engines that power our Champ Cars, because they can identify with the engine manufacturers' products on the street," said Andrew Craig, CEO of Championship Auto Racing Teams (CART). "CART is unique in that we have many engine and chassis combinations that teams can utilize to go racing. The engine manufacturers have to work very hard, and the chassis suppliers have to be very innovative as well. It all makes for a very competitive series."

Mercedes-Benz's test-bed is the transient dynamometer located at Mercedes' Stuttgart research and development facilities. This dyno allows engineers to simulate all the demands placed on the E3 powerplant, from shifting and clutch operation to aerodynamic drag, using a full gearbox assembly and data gleaned from actual race laps. Mercedes engineers then can custom-tailor the engine map (the Magneti Marelli software code that controls such parameters as fueling and ignition) to maximize performance and fuel efficiency for specific ovals or road circuits.

"The Mercedes-Benz transient dyno in Stuttgart gives us an opportunity to be more prepared when we arrive at a circuit," said Paul Ray, vice president of Ilmor Engineering, Mercedes-Benz's race-engine design and manufacturing arm. "If Lola and Reynard can be more prepared before turning a wheel, their teams are likely to be more competitive as well. But it's the work we do together that really maximizes the total package."

Rigorous in-house testing allow Reynard and Lola to perfect a setup before arriving at the circuit because they can evaluate the performance of suspension and chassis components under simulated track conditions. The combination of data acquired from the race circuit and wind tunnel can be used to replicate any race track in the world.

Months before testing begins, chassis engineers must design their car around the Mercedes E3 engine and its supporting systems. Mercedes-Benz's V8 powerplant was designed to be smaller and lighter than other Champ Car engines-a huge benefit for chassis designers.

"A large engine is better for stiffness, but in many ways, the lower, lighter design is better," said Simon Marshall, design engineer for Lola Cars. "We have to make up the weight in ballast, but the Mercedes design lets us put that weight where we would like to produce optimal aerodynamic performance. It gives us more flexibility. Some engines require extra scoops that can negatively affect the car's aerodynamics, but the Mercedes engine doesn't require those. It's a very neat system that wasn't hard to package."

Reynard Motorsport found similar advantages from the E3 powerplant. "We changed our gearbox design completely to make the best use of the engine's lower center of gravity," said John Thompson, drawing office manager for Reynard. "We were able to do some things with the undertray that helped the car. We can achieve more downforce with the Mercedes-powered cars than we can for the others."


The Seven Post Test Rig: A Primer The seven-post test rig consists of seven flat pads atop independently controlled hydraulic actuators. Using race data, a test-car and a set of tires, the rig can replicate the forces exerted on the car from any race track in the world. The rig allows teams to analyze many variables, including torsional load dynamics, component stiffness, the effects of weight transfer and ride-height sensitivity. Thus, any combination of aerodynamic and mechanical setup options can be customized, examined and refined to maximize the car's performance under actual racing conditions.

A Huff and a Puff: How the Wind Tunnel Works Reynard and Lola utilize wind tunnels featuring 50-percent-scale models and wind speeds up to 135 mph to optimize air flow over and around a car for peak efficiency. The model is computer controlled from outside the tunnel, allowing engineers to vary the angles of pitch, roll and yaw.

"In the wind tunnel, we work on reducing drag for more straight-line speed," said Simon Marshall, design engineer for Lola Cars. "We measure the power of an engine by speed on the straight, and the chassis can really screw that up if there is too much drag. It's more efficient for us to minimize drag than for the engine manufacturer to produce more horsepower."

In addition to CART, Mercedes-Benz defends its Constructor's Championship in Formula One with the West McLaren Mercedes team.

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Series IndyCar
Drivers John Thompson
Teams Team Penske