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ILLINI OUTLAW DIESEL’S ’02 DURAMAX BUCKS THE PURPOSE-ONLY PULLING TREND

In the age of purpose-built, competition only pulling trucks, many enthusiasts like to harken back to a time when things were simpler. You know, when you could pull your truck on Sunday and then drive it to work on Monday. While those days are likely gone for good, a few diehards are still able to win in the dirt with a truck they regularly drive on the street.

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At the heart of the ground-up build rests an LB7-based Duramax that’s reinforced with Wagler Competition Products connecting rods, Diamond Racing pistons, a Wagler alternate-fire camshaft, and ARP fasteners from top to bottom. To keep the engine efficient (and ultimately, street friendly), Karker elected to run non-de-lipped, factory-compression pistons. The heads are stock (and were sourced from a Kodiak, ironically enough) aside from a set of Performance valve springs from Hamilton Cams and Merchant Automotive heavy duty chromoly pushrods.

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The LB7’s rotating assembly was balanced by “Bert” at River City Diesel in East Peoria, Illinois, and topped off with an ATI super damper. A billet flex plate from BD Diesel, rated to handle 1,500 lb-ft of torque, also made it into the balancing process.

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To keep the potent LB7 anchored between the frame rails, Karker fabricated a set of stainless steel motor mounts. It’s important to remember that without properly battening down a high-torque diesel engine it will twist in the chassis, which can lead to damaged motor mounts, excess wear on the transmission mount (and transmission case), or both.

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A remote turbo mount moves the charger out of the lifter valley and makes swapping turbos a seamless process (and luckily for Karker it’s allowed in the Pro Street Diesel Truck class). Having the ability to change out a charger in a timely manner is ideal in the truck pulling world—where turbo technology is always improving and you can literally hook to the sled just about every other night. The remote mount system was built by Wehrli Custom Fabrication in Sycamore, Illinois, and utilizes a T4 mount/pedestal, 2-inch stainless steel up-pipes, and reverse flow 3-inch intercooler pipes.

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As for the turbo itself, this is not going to be the charger used in competition (hence the map groove and 80 mm inducer). Rather, this turbo served as a mock-up piece while Karker was waiting for his new 2.6-inch (66 mm) smooth-bore unit from Diesel Technology Source to arrive. While smooth-bore turbo rules undoubtedly limit horsepower, they eliminate all the “gray area” map groove chargers of yesterday, not to mention they simplify the tech process tremendously.

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Replacing the factory exhaust manifolds is a set of high-flow, cast-iron units from PPE that’ve been wrapped. The PPE manifolds route exhaust gases through a set of 2-inch-diameter Wehrli Custom Fabrication up-pipes fabricated from durable 11-gauge stainless steel.

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Getting away from the factory Y-bridge design, the LB7 employs a Street Intake from Wagler Competion Products. The cast-aluminum manifold’s intake neck is machined to accept a 3.5-inch V-band to rule out any blown intercooler boot scenarios at this high-boost location.

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With the ability to support 1,000 rwhp, a single 12mm CP3 from Dynomite Diesel Performance lives in the factory location. The stroker pump will send fuel to eight River City Diesel injectors, equipped with 200% over nozzles, and will receive its low-pressure fuel supply courtesy of a 220gph Titanium Series FASS system. Dialing in the injection system by way of custom ECM tuning via EFI Live will be left to Bob Petersen of DuramaxTuner.com.

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To ensure the five-speed Allison never skips a beat, Karker called upon two of the biggest names in the transmission industry: SunCoast and Goerend. Internally, the clutches and frictions have been upgraded thanks to a GMAX-5R-1 Raybestos rebuild kit from SunCoast, along with a billet C2 hub and P2 planetary. Inside the bellhousing sits a billet stator, triple-disc torque converter from Goerend Transmission. The converter’s “J” code designation means that its stall speed checks in between 2,700 and 3,000 rpm.

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Adequate cooling is provided for the C3 clutch pack through the use of Goerend Transmission’s PTO covers. Starved for oil in stock form, Goerend’s billet-aluminum covers direct ATF through a hole in the transmission case, which supplies muchneeded lubrication (and cooling) to the C3 clutches at all times.

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Safety requirements for the Pro Street Diesel Truck class dictate that an approved transmission blanket be used. This multi-layer Kevlar material unit came from DJ Safety, and Karker told us it was a breeze to install thanks to the cab being off the truck.

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Use of a sizeable, remote-mount transmission cooler indicates that the truck will see more than just the dirt. With the loose stall converter creating considerable heat during street driving, this aluminum Earl’s Performance transmission cooler should have no problem keeping ATF temps in check.

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A Merchant Automotive transfer case brace ties the 263XHD to the Allison’s tailhousing, which helps reinforce each of them in the event of a drive shaft or U-joint failure. To rule out the inevitable “pump rub” problem common to the 261XHDs and 263XHDs, one of Merchant’s transfer case pump upgrade kits was also installed. Karker plans to pull with the transfer case in Lo, the transmission in Third gear, and the engine seeing upward of 4,500 rpm.

Andrew Karker of Illini Outlaw Diesel is one such believer. A longtime truck puller and Duramax guru, he entered the sport at a time when your daily driver doubled as your puller—and that work-andplay mentality has never left his mind. As you can imagine, when his local sanctioning body (the Illinois Tractor Pulling Association) introduced a street based truck category for 2017 Karker immediately got to work building something that could compete.

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Built to do battle with the sled, this custom, one-piece rear driveshaft came from Driveshaft Specialist of Texas. It’s made of 1/8-inch wall aluminum and accommodates 1480 Series Dana Spicer U-joints.

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Dirty Hooker Diesel’s rifle-drilled axle and billet spool kit make the rear AAM 1150 all but indestructible. The spool is built from 4340 chromoly steel and is rifle-drilled for weight savings. The larger 38-spline axle shafts required reaming of the axle tubes. Once the body is mounted, the rear suspension will be blocked solid.

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Added insurance for the rear differential comes in the form of a girdle that was built by Wehrli Custom Fabrication. Behind the cast-aluminum PPE diff cover rests a ring and pinion with a 3.73:1 ratio. The front AAM 925 also houses 3.73 gears, but was outfitted with a Lincoln locker and a billet front differential slider from Dirty Hooker Diesel.

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Keeping the rear wheels digging, the AAM 1150 from rotating, and the (half-ton) leaf springs from twisting is a set of One Up Offroad traction bars. Arguably the highest-quality, best-performing bars in the industry, the long-gusset units found on Karker’s Silverado employ bolt-on frame and axle mounting brackets that incorporate polyurethane bushings.

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The truck’s hitch system was designed and built by Wehrli Custom Fabrication to meet the IPTA’s Pro Street Diesel Truck class rules (we’ll note that a 24-inch maximum hitch height will be observed). The hitch is designed to clear a Big Chevy Hitch receiver hitch mounted below the truck’s roll pan.

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As for the front suspension, Kryptonite upper control arms work in conjunction with a 6-inch Zone Offroad suspension lift and Fox 2.0 Performance Series IFP shocks. Adjustable MaxxCam 2 torsion bar keys from Suspension Maxx will allow Karker to obtain the exact height he’s after.

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Forgoing tie rod sleeves, Karker scrapped the OEM tie rods completely in favor of the popular Kryptonite series units. Thanks to their utilization of massive 1-1/8-inch hexagonal steel bodies, the Kryptonite series tie rods are roughly two and a half times stronger than the OEM units.

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A burly Kryptonite Race Series center link works in conjunction with the aforementioned Kryptonite series tie rods, and a Kryptonite Deathgrip idler arm is also part of the puzzle. The Deathgrip idler arm is CNC-machined from a solid piece of billet steel and features maintenance-free, dual-sealed roller bearings and a heat-treated 4140 chromoly stud.

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Further reinforcement of the idler side of the truck’s steering system is this Kryptonite Xtreme idler support bracket. It’s made from ¼-inch-thick steel plate with its middle gusset MIG-welded in place.

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This was the final addition to the truck’s steering equation: a steering box from RedHead Steering Gears. While Karker had to replace the high-mile factory steering box on the ’02 model year Silverado out of necessity, these steering boxes are highly revered for their ability to tighten up the steering play in ’99-07 GM trucks.

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All-terrain General Grabber AT2 tread measuring 35×12.50×20 will be the source of the truck’s bite in the dirt. And bringing the street truck look full circle is a set of 20×10 R.E.P.R. wheels from Sota Offroad.

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The truck even sports drilled and slotted brake rotors. Why? Because this rig will see triple-digit speeds when it goes to the drag strip. Over the years Karker has built a reputation for being one of few pullers that can win in the dirt and then drive the same truck on the street. His last build, an ’04 LB7 GMC Sierra, was the truck to beat when hooked to the sled, and also ran 11.20s at the drag strip.

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So why do we think Karker can pull off campaigning a street truck that dominates the dirt? Because he’s done it before. His daily-driven ’04 GMC, pictured here, was known for putting it on the rest of the field in Work Stock and Hot Street-type classes in 2016, as well as running neck-and-neck with some of the strongest running 2.5 trucks in the region.

Coined the 8,000-pound Pro Street Diesel Truck class, key limitations entail a 2.6-inch smoothbore turbocharger rule and single-rear-wheel configuration. And although the field of trucks in this class can theoretically still be driven on the street, everyone knows that nine out of ten won’t be. Making a conscious effort to buck this purpose-only trend, Karker made sure each and every component that made its way onto his ’02 Chevy Silverado 2500 HD served two purposes: It would give the truck an advantage both in the dirt and on the pavement. The parts recipe employed in this build will likely result in a truck that makes close to 800 rwhp, competes at the front of the new Pro Street Diesel Truck field, and can run low 11s at the drag strip. Follow along for an inside look at the truck’s First Place-caliber powertrain, chassis, and suspension setup. DW