Lead The Stampede: 726 WHP Shelby Mustang GT500

October 18, 2013
Story By
Evan Griffey

Randy Bronson and Lori Snellenberg’s Mustang is one of those mesmerizing, more than meets the eye propositions that reveals more magic the deeper you look beyond the sheetmetal. This big-power Mustang is saddled up and ridden hard on a regular basis and the mods are targeted and well executed.

“I loved when Ford brought out the 2005 Mustang because of the styling; the retro look of a 1969 Fastback,” says Randy who calls Silverdale, Washington home, “and I was really excited when Ford announced the Shelby GT500 for 2007. I wanted a ‘08 because I used to own a 1968 Shelby GT500. I bought this car used in June of ’09…saved a bunch of money.”

When Randy saw the Super Snake with its retro 1968 Shelby-look hood he had found his first mod. “At the time Shelby would not sell the Super Snake hood so I turned to Bangastang in California, who sold a similar hood made by Trufiber with the recesses for the twist locks just like the 1968 Shelby. We were on our way.”

Next Randy turned his focus from the hood to what’s under it. “When I owned my 1968 Shelby back in the early ‘80s, the car was put on a chassis dyno and tuned to a whopping 400 whp, pretty good for that era, but only got six to eight miles to the gallon and required mixed fuel to get the octane rating above 100. Well, the new ‘08 versions typically dyno'ed around 425 to 450 whp factory stock - not bad but with the Super Snake out there making just north of 600 whp, I needed more than stock. So, I turned to Kenne Bell, the company had just introduced a liquid cooled 3.6 supercharger.”

Randy’s twin-screw supercharger displaces 3.6 liters, produces 17 psi of boost and features a Kenne Bell Mammoth 168mm manifold/throttlebody upgrade. Kenne Bell also offers 2.8-liter and 4.2-liter units for the Ford’s 5.4-liter V8. It should be noted that this is quite a gutsy move as the GT500 is a factory-supercharged proposition. Randy’s system is a substantial step up from the factory 2.3 liter blower. Fuel enrichment is handled by a set of Ford Racing 80 lb/hr injectors while 1-3/4-inch long-tube headers and a full exhaust from Kooks expedite spent gases.

Randy planned to drive the car often and race it occasionally, so a Stage 3 Snow Performance Water/Meth kit was added to the mix to ward off any possible detonation. Randy is quick to note that the spray nozzle from the water/meth be placed behind the throttle body because positioning it in front of the throttle plate will mess with the drive-by-wire electronics, putting the V8 in limp home mode.

Kenne Bell did not have a custom tune for Randy’s combination, so he hot-shoed it down to Fast Specialties of Vancouver, Washington, where the blower was installed and had the ponycar custom tuned on the shop’s Mustang Chassis dyno. With the rev limiter left in the stock setting, along with a conservative tune for 92-octane pump gas and water/meth injection, the boosted 5.4-liter put down 726 whp. A Shelby custom eight-quart racing oil pan and intercooler with custom dual electric fans were added for increased reliability. Speaking of reliability, Randy made some well-informed mods in the transmission/driveline area to keep those 726 horses corralled and ready to run. A four-inch diameter aluminum driveshaft by Axle Exchange spins a nine-inch Currie rearend while a Cobra Jet bell housing and MGW shifter enhance transmission performance.

The contact patch becomes a serious concern when you have 726 whp and track day aspirations. “I needed sticky tires and the biggest I could fit under the chassis of a ’08 ‘Stang. I turned to CCW for a set of custom wheels to fit 275-18s in the front and 315-18s in the back... this combo has worked very nicely both for the street and for those track days.” Sticky goes both ways and for the stopping side of the equation Randy’s stock Shelby set-up with EBC blue pads, Roush vented rotors and stainless lines has worked well for Pacific Raceways in Kent, Washington but not so well at The Ridge Motorsports Park in Shelton. So brake department mods will include Wilwood’s new carbon ceramic kit for the front. “I need to be able to drive this car deep into those corners and with the power and the brake upgrade this combo should work perfectly together.”

Suspension and chassis mods are a big part of the Mustang’s performance prowess. Randy has added a UPR Chrome Moly K-member, Whiteline anti-drive bushings, Tokico D-Spec struts and shocks, Eibach Pro-Kit lower springs, Whiteline front and rear adjustable sway bars, Maximum Motorsports caster/camber plates, Shelby upper panhard bar support and panhard bar, Metco lower control arms. A Steeda three-point frame rail and torque box bracing set-up joins a RPM 6 point roll cage with seat support and Simpson racing belts to up the safety factor. Randy says custom struts/shocks from Cortex Racing will be swapped in for the current Tokico/Eibach combination in the near future.

The cabin is dressed for success with a sweet G-Tech Pro EGS Tach, OBD II/wideband 02 modules and mounting system, a Shelby gauge pod with oil, fuel pressure and boost readouts.

While built to lead the stampede like any Mustang should, Randy reports the Shelby has won several Best Mustang and Best Shelby awards on the show circuit. “We have driven this car as far as Winnipeg, Canada, where the car set on cruise control at 80 mph got an amazing 19.7 miles per gallon, a far cry from 1968. Wow, technology has come a long ways since 1968.”

“The car has been used for various other vacations, just recently to Yellowstone National Park, where I always drew a crowd when parking the car. Thanks Ford for building such a great looking car and for that 5.4-liter engine that’s been able to take my current power level with no engine dis-assembly is amazing. Long live the Mustang, it is my favorite car.” We can see why, Randy. -Evan Griffey

Lead The Stampede: 726 WHP Shelby Mustang GT500

What Others Are Reading