For performance enthusiasts, the new 2008 Ford Shelby GT500KR’s driving dynamics should be as big of an eye-opener as its acceleration, torque, horsepower and stopping performance.
The new model features an array of enhancements designed to give it the same poised and predictable handling at 120 mph as it has at 60 mph, according to the performance engineering team at Ford SVT in collaboration with Shelby Automobiles. The team has created the fastest production Mustang ever. This Mustang can take curves at speed.
The new GT500KR’s handling is the result of a clever combination of chassis engineering and aerodynamic honing, proven by its 1.0g lateral acceleration skidpad capability.
“The new GT500KR handling story is all about balance,” said Jamal Hameedi, chief engineer of Ford SVT.
“That’s the big result with new GT500KR dynamically,” agrees Gary Patterson, Shelby Automobiles chief test driver. “Its balance makes this car very confident and predictable to drive, even on the limit.”
Sharp Aero
Just as on the race track, aerodynamics has played a major role in shaping the dynamic capabilities of the 2008 GT500KR.
“Our objective was to build on the GT500 to give the new model more dynamic balance, reflecting its higher power output,” said John Pfeiffer, SVT product design engineering specialist. “We focused our efforts on creating even downforce levels front and rear. That meant finding more frontal downforce than the previous model.”
Extensive engineering work was devoted to deliver more front downforce, starting with the most obvious aerodynamic feature on the new car – its slick carbon-fiber front splitter.
The new splitter is an all-new profile, more aggressive than that of the GT500. It is deeper and consistently full in shape, mirroring the shape of the leading edge of the hood and bumper above it for design coherence. Its lateral edges, which kick up small aero wall shapes at the wheel arches, are a clear statement of performance intent.
The thinner splitter aids with approach angle clearance, but downforce is its primary role helping achieve a 31 percent improvement. The splitter structure creates a flat floor shape under the front portion of the bumper shape to the leading edge of the front wheels. Enclosing this area provides a significant downforce enhancement.
The splitter underside also incorporates an integral brake cooling feature, with molded shapes inspired by NACA ducts. At the rear, the new GT500KR has a less prominent spoiler, a design to balance front-to-rear downforce variances. That’s an important part of its balance and poise at speed.
“You have to experience the new KR at speed in a curve to feel the difference,” Pfeiffer said. “It has an absolutely minimal aero moment of just 54 lb.-ft. at 120 mph, a 92 percent improvement versus the GT500. That is central to its confident handling ability. Because it’s just as happy at 120 as it is at 60, the GT500KR is a very special performance car.”
‘Only’ 40 More Horsepower?
KR’s slick new aero has another special impact on performance feel.
“If you drive the GT500 and new KR back to back, you might accuse Ford SVT and Shelby of sandbagging because the car feels like it has more than 40 extra horsepower,” says Patterson.
“That’s an effect of the aerodynamics,” says Pfeiffer. “Our computer model predicts a four-tenths-of-a-second zero-to-150 acceleration effect from the aero alone. That makes the horsepower go farther.”
Chassis improvements engineered by Ford SVT and Shelby Automobiles complement the aero enhancements – and not every component is bigger for better performance. In fact, the new car is 22 pounds lighter than the current GT500.
“We reduced the diameter of the rear sway bar for just the right grip under power coming out of a corner,” said Kerry Baldori, SVT chief vehicle engineer. “That’s just one example of the amount of tuning that went into engineering the KR chassis.”
That tuning and the weight reduction are immediately obvious in the GT500KR’s light and responsive steering. Impressive given the aggressive size and stickiness of new 18-inch Goodyear tires – 255/45 series in front, 285/40 at the rear – mounted on distinctive, forged and polished wheels.
Powertrain calibration also makes GT500KR ‘street friendly’ despite its impressive performance credentials. It has a gentle, balanced feel at low speed when cruising around town and an easier launch feel.
Carbon Fiber Hood Delivers Increased Performance Under Pressure of 540 Horses
The new 2008 Shelby GT500KR is a performance car that knows how to manage pressure, thanks to carbon fiber components that do more than just look fast.
The new “King of the Road” features the first carbon fiber hood for Ford or Shelby. The hood is a sculpted work of art, with the right science under its skin to deliver real performance impact.
“This is our first-ever production application of carbon fiber, and it is fitting that we developed it with Shelby Automobiles,” said Ford SVT chief program engineer Jamal Hameedi. “It’s there purely for performance. It brings important aerodynamic and weight-reduction benefits that translate into enhanced performance for our new King of the Road.”
Art and Science of Performance
Delivering more power and performance in the new KR meant a more sophisticated approach to managing underhood aero pressure, especially at high speeds. The new carbon fiber hood incorporates aggressive vents in its leading edge and large rear surface ducts on each side – cues that make the performance pedigree of this latest Ford-Shelby collaboration immediately clear.
But it’s the underside of the hood where the really magic happens.
Carbon fiber, cured at high temperature in an autoclave, allowed Ford SVT and Shelby engineers to create a complex aerodynamic pressure management system.
This architecture creates two pressure zones under the hood – a high-pressure zone for fresh air intake for combustion and a low-pressure zone that expels hot engine compartment air.
Intake air for the supercharger is fed via the leading-edge intake vents. Then the underhood ducting routes it directly into a high-pressure subcompartment at the left-front corner of the engine compartment. Inside the subcompartment, separated from the rest of the underhood area by a robust rubber sealing system, is a large, conical, performance intake filter for the cool, fresh intake air.
The aerodynamic properties of the new hood were perfected in the wind tunnel after extensive computer modeling using computational fluid dynamics.
The hood is locked in place – and its complex aero performance is ensured – by artful stainless steel hood pins that lock the front corners into place. Even the hood pin shape is aerodynamically honed for reduced drag.
The rest of the underhood is a low-pressure zone, thanks to the large anterior ducts that effectively suck hot air out of the engine compartment at speed. This optimizes the effectiveness of the engine cooling systems, which are critical to performance.
Having large louvered ducts on the top of the hood requires careful engineering to protect the engine and underhood components – especially electronics – from water.
Water is indirectly routed downward through underhood ducting to drains that have been carefully placed. Hot engine compartment air is pushed up through 10 smaller underhood vents and out through the larger exterior vents. The unique water management system and the use of carbon fiber for the hood eliminate the likelihood of corrosion – a typical issue for collectors.
“This hood architecture helps the new KR deliver its 40-horsepower increase without sacrificing refinement and practicality for street use,” Hameedi said.
