Special Coverage

Chicago Auto Show

Ford Motor Co.’s Special Vehicle Team will introduce at the Chicago auto show a more powerful, lighter version of its ’11 Shelby GT500 Mustang that dodges the U.S. gas-guzzler tax.

The fuel economy gains over the previous model come courtesy of a number of modifications, including an all-new aluminum-block 5.4L supercharged V-8 engine that shaves 102 lbs. (42.3 kg) from its cast-iron predecessor.

Despite producing 550 hp and 510 lb.-ft. (691 Nm) of torque, a 10-hp increase compared with the ’10 Shelby GT500, the vehicle achieves 15/23 mpg (15.7-10.2 L/100 km) city/highway, a 1 mpg (0.4 km/L) increase in each category.

A new Ford-patented technology, dubbed Plasma Transferred Wire Arc liner coating, improves the engine’s overall performance and durability and reduces friction between piston rings and cylinder bores.

The process includes applying a 150-micron composite coating containing nanoparticles on the internal surfaces of the cylinder bores, replacing cast-iron liners normally used in aluminum blocks and shaving off some 8.5 lbs. (3.8 kg) compared with the outgoing engine.

The PTWA process combines air and electricity to create a 35,000º F (19,426º C) plasma jet that melts a steel wire fed into a rotating spray gun.

Using atomized air, the melted wire is sprayed into a machined surface of the cylinder bore. During the process of melting and applying the metal, the steel wire oxidizes, creating a composite coating of both iron and iron oxide.

The technology was adopted from the aerospace industry, says Glenn Jorgensen, SVT powertrain chief.

“We’ve invented a coating as a replacement for cast iron that delivers improvements in power and performance and fuel economy,” he says.

The new aluminum-block engine is based on the same architecture used by the Ford GT supercar offered between 2005-2006. But due to an improved block structure, the powerplant now exceeds the GT’s 500 lb.-ft. (678 Nm) of torque.

The Shelby GT500 is available in both coupe and convertible body styles, with the latter undergoing structural improvements to reduce the chassis shake typical of drop-tops.

By adding a front brace connecting primary and secondary crossmembers, combined with A-pillar stiffening foam, Ford engineers were able to increase the convertible’s lateral stiffness by 12% vs. the ’10 model.

“One of the biggest challenges for this Shelby (was to make) the convertible act and feel like a coupe,” says Jamal Hameedi, SVT chief nameplate engineer. “Before, they had a very different character. (The convertible) is now very much a sports car.”

For those seeking a “racetrack ready” Shelby, Ford introduces the SVT Performance Package available on both coupe and convertible models.

The optional package includes new Goodyear Eagle F1 Supercar tires, co-developed with Ford. The tires borrow technology used in the racing industry to deliver enhanced wet and dry performance, Hameedi says.

The Performance Package also adds new 19-in. forged-aluminum wheels in front that are 4.7 lbs. (2.1 kg) lighter than those of the base Shelby GT500. Around back are 20-in. forged-aluminum wheels that shave 2.8 lbs. (1.3 kg).

Due to the new performance tires, engineers were able to tune the chassis and shocks and stiffen front and rear springs for what Ford says is race-car-like handling.

All versions of the ’11 Shelby GT500 come mated to a 6-speed manual transmission.

Despite the enhancements, the ’11 Shelby still utilizes a solid rear-axle, while competitors such as the Chevrolet Camaro use a more sophisticated independent rear suspension.

However, Kerry Baldori, SVT global performance vehicle chief functional engineer, downplays any disadvantages of the solid rear-axle setup.

“We don’t see any negative impact; it’s fully competitive,” he says. “The solid axle is very much refined, and one of the better setups you can get.

“There are some disadvantages on rougher roads, but it works well on the track,” Baldori says. “The evolution of the axle has (been going on a) number of years, so it’s equal to an independent (setup).”

Ford has yet to reveal pricing for the ’11 Shelby GT500 or the Performance Package, both expected to be available this spring.

bpope@wardsauto.com