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2003 Chevrolet Silverado 2500 HD - Maximum Power

A 1,300HP, Street-Driven Duramax

Jason Sands
Mar 1, 2009
Photographers: Jason Sands
Photo 2/14   |   2003 Chevrolet Silverado 2500 Hd left Side Angle
Buck Spruill is a man who is never satisfied. That might explain why he's taken a regular '03 Chevrolet 2500HD with a 300hp, 6.6L Duramax diesel engine, and transformed it into the 1,300-horsepower monster you see on these pages. The road has been long and hard, and he's broken numerous parts along the way, including 40 (that's four-zero) Allison transmissions!
Before we get too deep into the transmission story, we'd better get you up to speed on the rest of the truck. The engine that produces Allison-melting power is based off an '03 LB7 block that has been fortified with aftermarket rods, 15:1 compression pistons, ported heads, a cam, head studs, and valvespring setup, all from TTS Power Systems. Burkett Racing engines performed all of the machine work and engine assembly, and the heads were fitted with O-rings and LBZ valves.
Up top, a Garrett GT4202 turbo provides a whopping 65 psi to the maxed-out engine, while up-pipes from a C4500-series truck, and a 4-inch downpipe provide plenty of exhaust flow in, and out of, the turbocharger. A three-stage NOS Launcher nitrous system was also used, and it has been modified by Buck into a direct-port unit. This way, Buck can inject nitrous into each individual cylinder, controlling EGTs as well as adding an estimated 400 additional horses. Buck also has lots of fuel, thanks to an ATS dual CP3 kit with Industrial Injection CP3 pumps, and Industrial Injection injectors that flow a whopping 100% more than the stock units. Tuning was handled by TTS Power Systems.
With an estimated 1,300 nitrous-assisted horsepower at 4,000 rpm, the truck has been far from reliable. "We'd take it out in front of the farm on a test run and lean on it a little," Buck recalls. "Half of the time, the truck wouldn't make it back to the house."
Where normal people would have given up long ago, Buck still wanted his truck to be one of the fastest diesels out there, even if it meant switching brand loyalty a little. "I called Ron Wolverton up at Sun Coast Transmissions, and asked him if he was interested in helping me out. He thought about it for a day, then called me and asked when he could have the truck." Three weeks later, it was ready.
When the truck arrived back home to Roper, North Carolina, it had a Sun Coast full metal jacket Dodge 47RE transmission installed where the Allison used to reside. Nicknamed the Duraflite, the transmission was surprisingly easy to adapt to the Chevy. A special engine plate, flexplate, and torque converter were used, but the stock driveshafts and crossmember were retained, making for a pretty simple swap. With billet input, output, and intermediate shafts, this transmission has proved extremely reliable through a full year of racing.
All of Buck's hard work paid off last year when he made his first few trips down the dragstrip with his new engine and transmission. We're starting to get used to street-legal 11-second trucks, but this thing is in a league of its own. Buck has driven his hot rod Chevy to the track, then flashed down the quarter-mile in 9.70 seconds-and that's lifting at 1,000 feet. Buck's perseverance paid off, and his hard work has made this nitrous-equipped, Dodge-transmissioned, Duramax-powered Chevy one of the quickest 4x4s on the planet. DP


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