Digging Holes: An ’02 Silverado Daily Driver Turned Sled Puller
When you make a living beefing up Allison 1000’s, it takes more than a blown transmission to keep you from purchasing a mint-condition, LB7 Duramax-powered Chevrolet Silverado 2500 HD. In the case of Jeff McCord, a big Duramax fan and avid truck puller, you could say he struck it rich when this Bow Tie popped up for sale at the local dealership. Upon closer inspection of the ’02 ¾-ton, he noticed the blue paint gracing the engine—the same blue paint used by SoCal Diesel, one of the most renowned Duramax engine builders in the diesel industry.
Without negotiating, he paid the asking price and hauled the truck straight to his shop, LinCo Diesel Performance, and set to work building the trans. Less than 24 hours later, the four-wheel drive LB7 he stole for 8K was 100-percent drivable and even became his daily means of transportation for a half a year. Then, when Jeff’s thirst to go truck pulling simply had to be quenched, he went to work converting the classic body Chevy into a 900hp fire-breather, with the sole purpose of hooking it to the sled.
Jeff’s category of choice, the 8,500-pound Work Stock field, wouldn’t be an easy one to dominate, but he and his crew had a few plans up their sleeve. First, they retained and reinforced the factory IFS front-end. Then they bulletproofed the rear axle, added torrents of fuel, spec’d out the largest turbo that class rules allow and bolted 35-inch Mud Grapplers in place to ensure the Duramax never stops digging. Join us below for a quick once-over of this commuter-turned competitive puller.
All the Right Parts
Thanks to its time spent at SoCal Diesel, the LB7 engine had already been prepped to handle big power. As such, Jeff McCord wasted no time throwing gobs of fuel and air at the built Duramax. The 6.6L V8’s foundation is on solid ground thanks to an externally balanced crankshaft, secured via billet main cap girdle and ARP main studs. The OEM crank swings a set of Carrillo forged-steel connecting rods that are fastened to cast-aluminum Mahle replacement pistons with 0.120-inch deep valve-pockets. Valvetrain and cylinder head upgrades include SoCal’s #9100 sled pulling cam, 5-axis CNC port work, beehive valve springs and single piece billet rocker bridges. The block has also been machined to accept O-rings and larger, 14mm diameter ARP head studs.
A Small-Frame Turbo with A Big Bite
The name of the game in Work Stock is to squeeze as much power as possible out of the largest turbocharger allowed in the class. In this case, that turbo is a T4 flange, 66mm S300-based BorgWarner unit from Stainless Diesel. Inside the polished compressor housing, a billet, 66mm (inducer diameter) compressor wheel that uses Stainless’s dyno and track-proven 5-blade design builds nearly 60-psi of boost as the truck claws its way through the dirt. The competition-prepped S366 mounts to a twisted T4 turbo pedestal from Wagler Competition Products and makes use of PPE exhaust manifolds and stainless steel up-pipes.
Stroker CP3’s & 250-Percent Over Injectors
A high volume common-rail injection system begins with PPE’s Dual Fueler system. However, instead of running two stock displacement Bosch CP3’s, Jeff installed a 12mm version from Exergy Performance in the factory location and a belt-driven 10mm PowerFlo 750 from Fleece Performance Engineering up top. The two stroker pumps share the workload of producing the 26,000-psi worth of injection pressure that makes its way to a set of Exergy 250-percent over injectors.
Big Fuel from Start to Finish
To keep the CP3 pumps happy, each unit receives low-pressure fuel supply from its own, dedicated FASS system. As with the injection system, Jeff erred on the side of overkill here, too, as each FASS Titanium Signature Series system can flow as much as 250-gph. Each FASS sends diesel toward its respective CP3 via ½-inch hose and at a supply pressure of 10-psi. Supporting the dual FASS systems is a dual feed G&R Diesel sump installed in the factory fuel tank.
The Unbreakable Allison
Transmitting 1,550 lb-ft of torque and nearly 900hp to the ground wouldn’t be possible without a stout Allison 1000—and Jeff was definitely in his element when it came time to piece together a competition-caliber automatic. Hard-part upgrades include billet input, intermediate and output shafts, along with Xcaliber’s 6-pinion, billet P2 planetary and billet C2 hub. As for the torque converter, Sun Coast got the call, supplying one of its 1071 model triple-disc billet stator units with a stall speed that checks in at roughly 3,100 rpm. Other key components included Sun Coast’s GMax clutch kit, a performance valve body that entails a modified separator plate and TransGo Jr. shift kit and an Alli-Locker from Dirty Hooker Diesel.
35-inch Mud Grapplers
For a truck that spends its time trenching 300-foot lines through the dirt, only the most aggressive DOT tires on the market would do. This is why you’ll find a set of 315x75R16 Nitto Mud Grapplers on Jeff’s Silverado. Like many truck pullers, Jeff believes the Mud Grapplers offer the best bite in the business, and that their performance on looser tracks is hard to beat. The 35-inch extreme terrain tread aboard Jeff’s Chevy are mounted to 16-inch Baja model wheels from American Racing.
Battle-Ready AAM 1150
A rear axle faces a lot of stress in truck pulling. And while the AAM 1150 that originally came in these trucks was stout, a few reinforcements were added to both aid its durability and its functionality. For maximum traction, a spool was thrown in (as were 4.88 gears). For improved strength, an axle truss from Artec Industries, complete with 3/8 and ¼-inch mild steel gussets, was welded to the axle tubes. The rear leaf springs are still in place (albeit perched above 3-inch Top Gun Customz lift blocks), but suspension travel is nonexistent thanks to adjustable suspension stops. A set of LinCo’s street series bolt-on traction bars, made of 1.75-inch DOM tubing and incorporating 7/8-inch heim joints, quell axle wrap and leaf spring twist.
Turning to proven aftermarket components and a few in-house innovations, Jeff and his team were able to optimize the performance of the truck’s independent front suspension with the iron sled in tow. Nitrogen-charged, 2.5-inch stroke bump stops from Locked Off-Road and homemade pre-load bolts control the front-end’s minimum height. Thanks to these mods and the way Jeff has them configured, the truck’s chassis can rise but cannot drop down any further. This way, both CV axles are sitting in a straight line parallel to the ground during the course of a pull (when the CV’s are at their strongest).
Straight Center Link & Burly Tie Rods
In order to beef up the notorious weak points in GM’s IFS system, a straight center link and larger diameter tie rods were installed. The center link (pictured above) came from PPE, is precision-machined from 304 stainless steel and features a 7/8-inch bolt vs. the 9/16-inch factory one. PPE’s Stage 2 tie rods are also employed, which bring a 48-percent larger diameter toe-adjusting shaft to the table. On top of that, the tie rod bodies themselves are 40-percent larger than the factory units.
Keeping Them Digging
On race day, Jeff’s Silverado boasts 1,000 pounds’ worth of CAT tractor weights out front. The added half ton of heft, positioned significantly forward of the front axle, ensures the Mud Grapplers continue to dig as effectively as possible once the pan drops on the sled. To fatten up their foot print, Jeff airs the Mud Grapplers down to somewhere between 18-20 psi when on the track.
Storming the Track
When it’s go time, Jeff brake boosts the truck. Once his target rpm and boost pressure has been built on the starting line, he eases out of the hole, turns the 900hp Duramax loose, locks the torque converter and holds on for the ride. A typical pass includes the engine carrying 3,700 rpm, ground speed checking in around 30 mph and the truck finishing at or near the top of the class. Surprisingly, as of the 2019-2020 offseason rumor has it that Jeff might have his proven performer up for sale—a dream come true for anyone looking to get into the truck pulling sport and start out at the top.
Curious what other upgrades your IFS-equipped Chevy HD will need to hit the dirt or visit the drag strip? Check out our comprehensive checklist here.