Roush Performance builds the Mustang that proves that track performance really can be streetable...

Motor Trend’s initial comment about Roush Performance’s 427R Mustang was that there would be no sensible reason for most motoring enthusiasts to buy it, since the Shelby GT500 would be introduced not much later, at around the same price range.

 There are some differences in taste and philosophy, however, that would render Jack Roush’s conversion as the “better” of the two.

For example, where the 427R Mustang lacks in power, it more than makes up for in road handling and stability. In fact, two of the Roush ‘Stangs’ most important features are its upgraded springs and dampers, along with a completely revised rear suspension, using race-profile trailing links, mounting brackets and bushings to promote traction and avoid wheel-hop.

On the other hand, the ‘Stang enthusiast who decides to go with the Roush over the Shelby should be prepared for a driving experience that promotes suspension dynamics before it does outright engine performance. This is because the 427R, despite its name that suggests a motor of much more cubic inches, doesn’t bolster much more than a stock, 4.6 liter V8, the same V8 that can be ordered in a standard GT. However, Roush Performance establishes for itself a hallmark in high-tech horsepower, mostly through the use of forced cold air induction. This is accomplished through the use of a roots-style supercharger with an intercooler that puts out 5.5 PSI. The supercharger itself is a 1.5 L unit with a familiar three-lobe impellar design, pushing the most boost possible on the 4.6 motor without having to drop its stock compression.

This is where Motor Trend’s quip about the up-and-coming GT500 made sense; Roush’ supercharged 4.6 motor only made 435 horses with 400 foot-pounds of torque, while the soon-to-be-released, Shelby GT500 was rumored to produce 540 horses with 510 feet-pounds.

 Again, this was a fair trade-off: raw horsepower was sacrificed just a little bit so that handling could be further advanced. Jack Roush and Roush Performance then brought Ford’s pony car back to its Trans-Am circuit racing roots; with such undercarriage components as a brake kit with 14-inch, vented-and-slotted front discs, 4-piston front calipers and Cooper Zeon tires, the 427R ‘Stang was ready for anything that any closed-circuit track could throw at it.

But the relative lack of horsepower and the shortage of cubic inches with Roush’ 427R is nothing to point a finger at when you take into consideration the technique with which the car itself was built. In fact, Roush Performance’ use of intercooled supercharging on the 427R has resulted in a power boost that has actually ended with greater performance and efficiency; the roots-style supercharger helps the 4.6 motor to run with a 10% increase in fuel efficiency, while reducing overall emissions by 38%.

In an age where even performance cars need-be “eco-friendly,” Roush Performance, with their 427R Mustang, has established probably one of the high-performance industry’s best balances between street/track performance and everyday usability. True that the Shelby GT500 is the “brute” of Ford’s F-Body family, but then again, some motoring enthusiasts would rather have the driving experience over the fire-breathing extravaganza. Where Carroll Shelby’s recipe has been successful on the professional race circuit, Jack Roush’ has been equally successful when trying to mingle professional race with street.

- Sal Alaimo Jr., B. A. (6/10/11)

S. J. A.