Muscle Mustangs & Fast FordsFeatured Vehicles
Making the 2015 Shelby GT350 a Winner on the Sales Floor and at the Racetrack
On Track for Success
For engineers at Ford Performance, racing isn’t an excuse to escape the office for a few days but rather a way to validate their products in head-to-head competition with their worldwide rivals. Racing pushes both human and machine to the limit, exposing their strengths and weaknesses. So engineers wearing a Ford Performance shirt in the pits aren’t on vacation—they’re on the clock.
The Shelby GT350R-C is the latest iteration in a long line of production-based Mustang race cars. While the new racer has plenty of innovative technology, racing a Mustang to improve the breed is not a new concept for Ford, or its partners.
Along with Shelby’s 1965 GT350 models, Ford tasked former Texas chicken farmer Carroll Shelby to build 37 racing-only versions for SCCA’s B/Production class. These cars were known as “R” models. The racing Shelby was followed by factory-supported efforts behind the 1969-1970 BOSS 302, 1995 Mustang Cobra R, 2005 Mustang FR500C, and 2012 Mustang BOSS 302R.
For the new S550-chassis Mustang, Ford developed the Shelby GT350 and GT350R. The GT350R is more track-focused with things like unique magnetorheological suspension tuning and bodywork. In an effort to slash 130 pounds from the pedestrian GT350, the R gets carbon-fiber wheels and leaves a lot of parts (like the exhaust resonators, back seat, air conditioning, radio, and spare tire) at the Flat Rock Assembly Plant.
With the 2015 Shelby GT350R street legal, the competition-only variant is designated the Shelby GT350R-C. Today’s series of choice for production-based professional sports car racing is IMSA’s Continental Tire SportsCar Challenge.
The IMSA Continental Tire SportsCar Challenge pits lightly modified production cars against each other in a series of 2 1/2-hour events that include pit stops, driver changes, nationwide television coverage, and manufacturers eager to capitalize on a “win on Sunday, sell on Monday” marketing opportunity. Permitted changes to the cars focus on safety enhancements but also include measures to make the varying models of eligible cars competitive.
Most cars use the same 275/35-18 Continental race slicks, but IMSA officials use a combination of parameters, including minimum vehicle weights, engine air restrictors, and rpm limits, to keep the performance of varying cars in line. For example, the Shelby GT350R-C must use a final drive ratio of 3.31:1, carry a 21-gallon maximum fuel capacity, weigh at least 3,400 pounds, limit its maximum rpm to 8,200, and suck through a 58mm engine air restrictor.
Ford’s partner of choice in this endeavor is Multimatic Motorsports. Besides being an automotive supplier headquartered in Markham, Ontario, Canada, Multimatic has decades of production-car racing experience with Ford Motor Company, particularly with Mustangs. Like its earlier brethren, the Shelby GT350R-C was first developed and raced as a factory-supported effort. After the package is proven in competition, more GT350R-Cs will be produced for customer teams.
At the car’s debut at Watkins Glen on June 26, 2015, driver Scott Maxwell set the fastest time in qualifying to put the No. 15 Shelby GT350R-C on pole.
To get perspective on how the Shelby GT350R-C stacks up against its competition—including the Mustang BOSS 302R—we asked Ford Factory drivers Billy Johnson and Jade Buford for their perspectives.
17 series wins
The BOSS 302 is one of the best-handling solid-axle chassis cars ever built. I am a huge fan of the BOSS 302R and have had a lot of success with it (nine wins in a 302R, two wins in a FR500C, and one win in a FR500S). The S550 chassis with its independent suspension is a huge leap forward for the Mustang. After all, the Performance Package Mustang GT has similar (if not better) performance on track than the Boss. The Shelby takes that a step further with its suspension, brakes, aero, and of course the impressive flat-plane crank 5.2L V-8 engine that makes over 100 hp per liter and spins to 8,250 rpm!
The GT350R-C drives a lot more like a GT-style racecar than the BOSS 302R due to its more advanced chassis, suspension and aerodynamics—all of which come together to create the best handling Mustang ever!
I'm honored to be apart of the Ford Performance family and have been apart of the BOSS’s racing successes and now the early success of the GT350's return to racing. —Billy Johnson
1 series win, 7 pole positions
Our new Shelby GT350R-C shares an incredible amount of similarities to street-going GT350 and GT350R. The biggest differences between the GT350R and the BOSS 302 include the new GT350’s 5.2L flat-plane crank V-8 versus the 5.0L “coyote” in the BOSS 302, and the new independent rear suspension on the GT350 instead of the BOSS 302’s solid rear axle.
Because of these changes, the GT350 feels and drives very differently from the BOSS 302. The independent rear gives the drivers and engineers a lot more “knobs to turn” in chassis setup, which leads to one of the strengths of the GT350: its ability to roll quite a bit of speed on corner entry, and through the center of a corner, and put the power down on exit. This behavior is similar to Multimatic’s Aston Martins that I drove a few years ago.
Power delivery of the new flat-plane V-8 is very linear. It builds power all the way to redline. The BOSS 302’s engine’s power delivery felt like a plateau near the top of the rpm range. If I had to compare power delivery to another car, I would say the GT350 feels most similar to a Porsche or BMW… except their motors lack the bottom-end power of the GT350. Our engine makes a lot of torque in the middle of its rpm range, which gives us great acceleration out of the corners.
There’s a lot of other differences that make the GT350 a great car, but the powertrain and handling characteristics will most likely be the first thing a driver will notice when he or she gets behind the wheel. I'm very proud to be part of such a program, and it's great to see a manufacturer take such a giant stride from one generation to the next and deliver ground-breaking performance at a price that no one else can match. —Jade Buford
|Chassis & Safety Equipment|
|Seam-welded and mass-optimized Shelby GT350R production unibody fitted with FIA-specification Roll-Over Protection System (ROPS)|
|FIA-standard race seat|
|5-point harness and lateral restraints|
|ATL 79.5L (21 U.S. gallons) fuel bladder|
|FIA/IMSA-compliant fire suppression system|
|Naturally aspirated Ford quad-cam, dry-sump V-8 with flat-plane crankshaft, 5.2L displacement, assembled by Roush Yates Engines|
|Bosch MS5.0 ECU with engine calibration optimized for endurance racing|
|Stainless steel tuned Ford Performance Racing Parts exhaust|
|Tremec close-ratio, 6-speed manual gearbox|
|Ford Performance Racing Parts adjustable-ramp limited-slip differential|
|Bespoke MIL-spec, route-optimized wiring harness|
|MoTeC Power Distribution Module|
|Onboard MoTeC datalogger|
|Brembo 4-piston front and rear calipers with full-floating slotted rotors (380mm front, 355mm rear)|
|Race-tuned Bosch ABS controller|
|Adjustable coilover MacPherson struts with race-specific bushings, ball joints, and Multimatic DSSV adjustable cartridge-type dampers|
|Ford Mustang rear multilink IRS (independent rear suspension) with race-specific bushings, ball joints, and Multimatic DSSV adjustable dampers|
|Blade-adjustable front and rear antiroll bars|
|Wheels & Tires|
|18x10.5 BBS multispoke aluminum wheels|
|275/35-18 Continental racing slicks|