Roush Racing's 2001 Ford Mustang GT - Exercise In Engineering

It's no secret that Roush Performance is at the forefront of automotive technology and performance. Roush produces some sick Mustangs and trucks for public consumption, as well as a catalog of parts for late-model Fords. Jack Roush has had major success in Trans Am, drag racing, and of course, NASCAR, and seemingly each week on tracks and on the street, he continues to build his racing empire. While he guns for championships in NASCAR, his son Jack Jr. and his daughter, Susan McClenaghan, drive towards their own championships-Jack Jr. in the Grand Am KONI Challenge series and Susan in the NMRA's Modular Muscle class.

With such intense dedication, it's no wonder Roush parts work well and fit right, and the family's racing has a lot to do with that. The company's street vehicles look and perform great, and its racing teams are always in the championship hunt. But we hardly hear what happens behind the scenes; in particular, how parts get developed and integrated into new Roush vehicles. We often see the shiny bits land in our nearest catalogs, but you have to wonder, how does it come to fruition?

The answer is right in front of you in the guise of this '01 Mustang GT, piloted by Jack's daughter, Susan. Despite having only a few years of drag racing experience, Susan has shown great ability behind the wheel of this 10-second Mustang. By day, the talented heiress is also the caretaker of the Roush Automotive Collection that currently has a fleet of more than 115 very cool and interesting cars.

In its heyday, Susan's Stage 3 served as Roush's engineering workhorse for emissions certification, calibration, and development of its Stage 3 engine package for the then-current '99-'04 Mustangs. The folks at Roush's Special Vehicles division wanted a rock-solid foundation to develop hard-charging engine components, so they turned the otherwise-stock GT into a dedicated track star-albeit one that would face real-world competition in the NMRA Keystone Ford Racing series.

There was no time to waste, so the vehicle was gutted to a pure shell, and its transformation from street car to race car was underway. A full cage was installed to reinforce and underpin the Fox-4 chassis, while the crew started the sus-pension build with AJE's tubular K-member, lower front control arms, and coilover springs with a set of Koni struts. The workshop then did away with the Mustang's stock rear sus-pension and fitted a set of RJ Race Cars ladder bars to locate the Moser 9-inch rear. With Strange double-adjustable shocks and Hypercoil springs left to manage the motion, it was up to the motivating forces under the hood to get the party going.

Since downtime would have been detrimental to the Stage 3's supercharger development period, this car needed a bulletproof foundation with a failure rate of zero. At the same time, it had to be similar to what a typical Mustang owner would drive, so the displacement remained the same as stock while key internal upgrades were made for the sake of reliability. Essentially, the engine is what you'd find in a Stage 3 Mustang, but it's been treated to a few racing tricks. Starting with the stock '01 iron block, a slight cleanup hone allows the Wiseco pistons to slide freely in the standard-size bores. With a steel Cobra crank replacing the GT's cast unit, and a set of steel I-beam rods by Roush moving the shiny new slugs to and fro, compression is dialed in at 9.6:1. A Cobra oil pump provides the slippery stuff to all the bits on the topside, while the remainder of the Two-Valve mod motor is blue-printed for exacting performance.