Jeff points out that, as in other motorsports, great tires are a must for drifting. Even while spinning and smoking, it takes good tires to provide the feedback, and-yes-grip, to accurately and consistently hang the tail out. Thinking junk tires would be fine-and a lot cheaper-Jeff says they initially tried Maypop rubber but quickly turned to the BFGs when the el cheapos revealed their inconsistent, low-grip personality. It's a shame, too, as two laps are about as long as rear tires-even the killer KDs-last when drifting.
Definitely more durable is the good, old American iron under the hood. The 4.6 GT engine is internally stock but augmented with a Vortech V-2 S-Trim running in the 9-10 pounds of boost range. A 255-lph Walbro in-tank pump supplies the fuel and 38-lb/hr injectors spray it. Distribution is handled by an off-the-shelf Vortech system-that makes it an Autologic chip. Iridium plugs from Denso greatly reduce misfiring in conjunction with one of AEM's new CD ignitions. Air metering is via the stock GT's 80mm meter, and the whole was installed and tuned by Factor X Motorsports in Las Vegas.
Reasoning that a ton of rear gear would aid drifting, Progress Group installed 4.10 gears in the otherwise stock 8.8 rear axle. That did the job, giving the hard hit and rev needed to keep the rearend spinning while drifting. But with the blower power on tap, these gears have proven to be too much on the street and road course, so a change to 3.73 or possibly even 3.55 gears is in the works.
With either gearset giving 359 hp and 365 lb-ft of torque at the rear wheels, this Santini Custom Graphics yellow attention-getter is no slouch in the straightline department. At press time, quarter-mile testing had not been run with the blower, so we don't have a number or speed for the combination, but given a good launch from the compliant suspension and sticky tires, the times and mph ought to be good. Previously, without the blower and using 3.27 gears, the car ran 13.93 at 105 mph at Las Vegas Speedway, which is at 2,000 feet altitude.
Of course, the real story is under the car, where Progress Group has installed every part it offers for Mustangs, along with a few others. To stiffen the chassis, the OEM convertible brace was added to the rear of the stock K-member, together with a set of Roush Performance bolt-on subframe connectors. Progress Sport Springs were fitted, lowering the front by 1.75 inches and the rear by 1.50 inches. These are linear-rate windings of 725 lb/in of rate in the front and 300 lb/in dual-rate progressive springs in back. A shorter pinion snubber was also fitted to work with the lowered ride height.
In front, Energy polyurethane bushings were fitted only to the stock lower control arms, along with five-way adjustable Tokico struts. Jeff says he's found the Tokico adjustability well suited to the Mustang, with a number 3 setting good for the street and a number 5 the right thing on track. An easy, 10-second, screwdriver adjustment at the top of the strut is all that's required. Working with the higher spring and shock rates are Progress' 1.38-inch tubular front sway bar (a lower-cost but heavier, solid bar of identical diameter is optional).
In back, the same Tokico five-way adjustable shocks were fitted, along with Progress' aluminum lower control arms. These lightweight arms are reinforced for strength and are fitted with polyurethane bushings at one end and stock rubber bushings at the other. Our feature car also sported prototype aluminum upper control arms. Besides looking buffly industrial with their welded plates and lightening holes, these arms use a trick, high-angularity bushing to hugely reduce the infamous Mustang rear axle bind. This is done with a central steel sphere at the heart of the bushing. The sphere has two cylinder-like extensions to take the through-bolt and is cupped inside a pair of urethane cushions. This allows large angle changes by the steel ball without binding, as well as a high degree of precision thanks to the low-distortion urethane. It's a unique and clever attack on this critical bushing.