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Twin-Turbo 2003 Corvette - Doctor's Orders

A Preeminent Corvette Physician Prescribes A Twin-Turbo Booster Shot

Eric Orban Jan 11, 2008
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For many car guys, the passion for all things automotive can border on obsession. And for some acutely fanatical enthusiasts, this fervor approaches the unhealthy. John Nestor is not ashamed to admit he falls into this category, attributing his car's progressively augmented performance to an obsessive-compulsive personality. Soon after purchasing a perfectly healthy new '03 Corvette convertible off the lot, Nestor developed a fixation with improving it. "I wanted to make a great car even greater, and make it a statement of my individualism."

To channel his mental malady toward something positive, Nestor sought the counsel of the performance practitioners at The Corvette Doctor, in St. Petersburg, Florida. Surgery was led by technician Chris Warne, who has overseen the entirety of this car's development. The first round of tinkering resulted in a 374-cube supercharged motor good for 650 horsepower. But Nestor wanted more from his Corvette; his "nothing in moderation" mentality demanded further increased performance. The good doctor decided it best to write a prescription for the automotive equivalent of anabolic steroids-a twin-turbo kit.

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The 408ci twin-turbo engine produces an impressive 840 hp and 700 lb-ft torque. Cryo-forged internals maximize durability.

The base of this bi-turbo behemoth is a 6.0-liter iron block bored to 408 ci. Its rotating assembly comprises an Eagle forged crank and H-beam rods, along with forged 9:1 pistons from JE. A set of Total Seal piston rings were added to handle the high turbo boost. Almost every engine component, from the valvesprings to the block itself, has been cryogenically processed. This was done in the "first, do no harm" spirit of the Hippocratic Oath, as the Vette is Nestor's only means of transportation.

Perched atop the block are custom-ported Dart 225 heads with Manley Extreme Duty exhaust valves and Severe Duty intake valves. At the heart of the engine is a high-rev Comp Cams XE-R camshaft with 224/230-degree duration, 0.581/0.592-inch lift, and 114-degree lobe separation. The valvetrain includes Comp R-series lifters, 0.650-lift dual valvesprings, custom-made Comp pushrods, and Harland Sharp non-adjustable rockers. A ported LS6 intake manifold feeds the heads' ravenous appetite for air.

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The prescribed Turbo Technology Inc. Stage X twin-turbo kit is an all-inclusive affair featuring a pair of Turbonetics T3/T4 ball-bearing turbos. A TTI Extreme intercooler resides in front of the engine, while a TiAL 50mm bypass valve rules out the possibility of compressor surge. Exhaust gases from the block are fed through TTI exhaust manifolds into the hot side of the turbos. The spent hydrocarbons and discharged wastegate gases are then channeled through 2.5-inch ceramic-coated downpipes and delivered into the atmosphere through a Corsa Touring exhaust system with Pro Series tips. The greater demands of both the fuel and oil systems have been addressed with custom work from The Corvette Doctor.

The automatic transmission in Nestor's car is a mechanical marvel in its own right. The factory 4L60E has been enhanced with 4L65E internals and a few other custom touches. As in the engine, a majority of the components have been cryo-treated for durability. The drivetrain also benefits from a Vinci 2800-stall torque converter and a rearend enhanced with 3.15 gears.

Nestor estimates that the combination is good for around 840 hp and 700 lb-ft of torque. These are impressive numbers, to be sure, but what makes them exceptionally remarkable is their use in a daily driver. With so much power in a ragtop configuration, this Corvette is a threat to high-style coifs everywhere. A top-down blast at wide-open-throttle will tousle even the most rigid, Ditka-like 'do.

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Not content to veil all the glory under the hood, Nestor sought to personalize the exterior of his C5. At the front of the car, he installed a Caravaggio Corvettes Blower hood and Specter Werkes/Sports exposed headlamp modules. These work in concert to give the face of the car a distinctive look with flowing lines. A Caravaggio Pace Car decklid covers the convertible top when it is stowed.

The most arresting aspect of the exterior may be found in its custom brake ducts. Beginning with off-the-shelf ducts from Breathless Performance Products, All Star Auto Body in Clearwater, Florida, faired the originally bolt-on pieces to fit in the body panels. The outcome is dazzling, and it makes the ducts on the '01-'04 Z06 look like a slapdash implement-ation by comparison. The product of these external enhancements is an alluring, yet balanced, appearance.

In keeping with the refined air of the exterior, the rolling stock has been upgraded to HRE 542R wheels. These are staggered 18 inches fore and 19 inches aft, and are wrapped in Michelin Pilot Sport tires-275s in front and massive 345s in the back. The rear wheelwells have been mini-tubbed to shoehorn in the broad expanse of rubber.

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Inside the cockpit, Auto Meter boost and fuel pressure gauges display the Vette's vitals on the A-pillar. The factory audio system has been upgraded with Sony XM components for rainy, closed-top days.

Nestor estimates the car's quarter-mile times to be in the 10-second range, but he has not been able to put those numbers to the test. When attempting to make a pass at a local dragstrip, he and his convertible were black-flagged by an official due to the car's lack of NHRA-mandated safety equipment.

To avoid marring the Vette's appearance, Nestor decided to forego drag racing altogether. "These are mods that I don't want to make to my daily driver," he says. "A roll bar would ruin the car's looks, in my opinion." In addition to using it as his regular commuter vehicle, Nestor takes his Vette to meets with the Tampa Bay Posse, a local Corvette club.

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As a testament to his obsessive nature, Nestor still has big plans for the car. "It's been a never-ending saga; it's always something!" he relates. The Corvette Doctor has planned a 300hp booster shot, with additions including a bump in turbo pressure (to between 15 and 20 psi!) and methanol injection. Four-digit power in a daily-driven car would certainly be a remarkable achievement.

Nestor has forborne the temptation to build a bare-bones race car for the road, and has in turn made something much more special. His Corvette melds beauty and brawn with real usability. The result is a dual-purpose car that can both drive Grandma to choir practice and willfully participate in high-speed hijinks. With its elegant exterior and gobs of turbo-boosted power, John Nestor's '03 convertible is the quintessence of what a fun-in-the-sun daily driver should be, and a tribute to his nonconformist spirit.



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