2005 Pontiac GTO - An Engineer’s Approach

This Supercharged ’05 GTO Was Built With Little Compromise

From the September, 2012 issue of High Performance Pontiac

By Don Keefe

Photography by Randall D. Allen

Engineers live in a world of limits. Their mission is to achieve a predetermined outcome, working within certain constraints at every step of the process. Those parameters are often determined by the realities of economics, the limits of technology, or the personal preferences of the client. Whether it is bringing to market a bathroom faucet or a launching a communications satellite, the finished product must achieve all goals, while working within those set limits.

For Martin [last name withheld], an engineer from Texas, working within a defined set of constraints is a daily reality. So when it came down to putting together the ideal performance machine for his own enjoyment, he decided that he would become the project manager to one of the most outrageous street-driven bullets ever to come out of the Lone Star State. His project would be a completely balanced performance package, from the drivetrain, to the suspension, to the brakes. If the power was that high, the rest of the car had to be able to accommodate. That level of performance was also going to be maintained for the navigation system, in-car entertainment, and occupant comfort. In a nutshell, he wanted the Batmobile with a slightly more sedate appearance.

In July of 2010, Martin purchased a clean Phantom Black ’05 six-speed GTO, which came with the RPO code-NBB Level 2 Sport Appearance Package and an owner-added Magnuson supercharger. Once he had it home, he called upon David DuSold, of DuSold Enterprises in Lewisville, Texas, to take on the project. As the owner/project manager, Martin outlined his vision for the car. This time around, the only constraints were Martin’s imagination and he had very big plans, indeed.

It’s no secret that DuSold Enterprises has earned a solid reputation in the early and late-model Pontiac community for its prowess in custom paint and fabrication work, and David was already hatching a plan as Martin was outlining his. His formula was to integrate a selected group of upgrades that each had been proven on their own. From there, other components could be custom-tailored to the build.

The 6.0-liter LS2 V-8 was and still is a very strong basis for a performance-oriented build. While some builders prefer the iron-block LSX or truck blocks, the aluminum block was deemed sufficient for the supercharged application by DuSold and Martin’s preferred engine builder, Patrick Sparks of Quality Motorsports in Lewisville, Texas.

Its stock bottom end was retained, though the rods were beefed up with a set of ARP bolts. The stock 243 heads were ported and fitted with stainless steel valves to handle the additional stress and heat generated by the induction system. The camshaft is a proprietary design with the approximate specs of 228/242 degrees duration at 0.050-inch lift and 0.575/0.585-inch lift when combined with the 1.7:1 Yella Terra shaft rocker arms.

In addition to the Eaton MP 112 supercharger, BMR 2.8-inch-diameter upper pulley, Innovators West six-rib pulley, and 10-percent overdrive harmonic balancer, Quality Motorsports used an East Coast Supercharging Maggie Tensioner bracket to prevent supercharger belt slip.

The custom-fabricated steel four-gauge pod features VDO oil pressure, fuel pressure, boost, and wide-band O2 gauges with a custom GTO script by Redline Gauge Works. Gauges all have peak and hold features with warning lights. Martin also had custom leather added to the shift boot, emergency brake and center console, all with red-leather stitching.

The supercharger system uses a two-stage charge cooling system, which includes not only the kit-supplied air-to-liquid intercooler, but also a custom-designed methanol injection system. This two-pronged approach was a necessity, as the charge air temperatures generated by the supercharger’s 17 psi of boost would otherwise detonate the engine to Kingdom Come. The progressive methanol injector is based on an Alcohol Injection Systems kit that has been augmented with a DuSold custom-fabricated 2.5- gallon aluminum tank with the pump sumped into the bottom. The air-to-liquid intercooler uses a Canton GT-500 extra-capacity tank to help control the heat.

While the stock MAF and ignition system remain, the GM 90mm throttle body was ported, and Injector Dynamics custom built, 60–lb-hr fuel injectors were added along with Magnuson Extruded aluminum high flow fuel rails. Racetronix/Lonnies Performance Automotive’s GTO 5.7/6.0 Double Pumper-Twin High-Output Fuel-Pump Kit delivers the petrol.

Spent gases are expelled through a set of Stainless Works long-tube headers with 1.75-inch primaries and 3-inch collectors. They exit through a custom DuSold stainless steel X-style pipe with a pair of 3-inch Magnaflow mufflers. Horsepower has been dyno’d at 600 at the wheels, estimated at 725 at the crankshaft, using 93- octane fuel.

Backing this formidable powerplant is the stock T56 six-speed transmission, featuring a JHP Pro series billet shifter, McLeod RXT Street twin-disc clutch, and an aluminum flywheel. The stock IRS differential has been strengthened with a Harrop Sports differential cover, and BMR 300M axle stubs and CV axle shafts. Likewise, a custom DuSold strut tower brace, a set of BMR weld-in subframe connectors, and a skid plate were also added to enhance torsional stiffness and protect the differential.

The front and rear suspensions have been upgraded with a Pedders Track II system, which includes custom front and rear springs, shocks and swaybars. Though the specs on the system have not been released by the manufacturer, we do know that the swaybars are larger and significantly stiffer than the production units.

An AP Racing six-piston Big Brake front kit with 14.25-inch cross-drilled and slotted two-piece rotors, and the matching AP Racing four-piston Big Brake rear kit with 13.00-inch cross-drilled and slotted two-piece rotors necessitated the use of 19-inch CCW forged one-piece wheels, which mount Michelin Pilot Sport 2 tires. The fronts are 245/35ZR19s on 9-inch-wide wheels, while the rears are 285/30ZR19s on 11-inch-wide wheels.

DuSold also handled the installation of the carbon fiber Banshee hood and the paintwork. The hood received Phantom Black PPG base/clear on the nostrils and extractors, as did the front and rear fascias. The grilles were painted satin black, as was the decklid, which also received a Reflective Concepts black arrowhead. David also retrofitted Jaguar XJS washers onto the wiper arms, so no holes had to be drilled in the carbon fiber hood.

With the project completed for now, Martin hit the road in his Goat. He reports, “It runs like a hamster on a wheel with a JATO pack strapped to its back, and it handles like a slot car!”

Does that mean he is finished with his GTO? Nope. Martin is looking toward the next phase of the build, which will likely include more power in the way of a 427-inch LSX with a TVS 2300 series supercharger. That should put the horsepower into four-digit territory. The question is, will that be enough for Martin?