The Limited Pro Stock Duramax puller that somehow holds its own in a sport full of Cummins competition.
Evan Davis has been in the truck pulling game more than 20 years, and it all started when his tow-rig—an ’02 LB7 Duramax—hooked to the sled for the first time. Since then, he’s campaigned several different trucks in the dirt and competed in everything from the 2.5-inch category to the old, 2.6 map groove class, to today’s 1,600+ hp Limited Pro Stock field. And although his setups have changed dramatically over the years, every puller Evan has pieced together has been Duramax powered. “I like the Cummins platform,” he told us. “But I’ve always enjoyed being a little bit different, and making it work.” That he has…
You’re looking at the Limited Pro Stock class Duramax that beat 60 other trucks at Diesels In Dark Corners XIV, and it’s also one of the only V-8s you can count on to finish in the top five at any given pull. So, how has Evan managed to make a Duramax such a threat in one of truck pulling’s most competitive (and Cummins-dominated) categories? By having decades of experience, possessing hands-on engine, fabrication, wiring, and tuning skills, benefitting from a great team, being meticulous on maintenance, and (of course) living in the “grey area” of the rules. “I’ll be the last guy to cheat, but there is always a grey area in pulling—and you have to run in that grey area to win.”
Purpose-built to be a dedicated open driveline puller, Evan’s “Grey Area” Chevy was methodically pieced together over a three-year period. A ’13 Silverado body sits on top of a heavily reinforced chassis with no factory cross members left to speak of. A dyno-proven engine combo, dialed in via a stand-alone ECU (and that often sees more than 5,000 rpm), powers the dual rear wheel Bow Tie down the track. A four-link system keeps the front-end biting the whole way, while a rear 20-145 Rockwell absorbs every shock load it sees. From head to toe, every single component bolted to the truck is there for a reason: to win.
In Evan’s own words: “the weak link is the block and crankshaft in the Duramax platform.” Reason enough to source an LML block—the cast-iron crankcase that’s least prone to cracking at high horsepower and torque—and filling its water jackets with HarkBlok. In place of the factory crank is a stock stroke Compstar unit from Callies, secured via billet Wagler main caps and ARP main studs. Cast-aluminum Mahle pistons measuring 0.040-inch over give the Duramax a slight increase in displacement and connect to a set of Carrillo rods. A proprietary camshaft, with a profile Evan’s been running for years, actuates the valvetrain.Solid cast, O-ringed Wagler cylinder heads top off the competition short-block. They’re anchored in place by way of ARP head studs and enjoy a bit of dress-up thanks to a set of Wagler’s billet-aluminum upper valve covers. Above that, Wagler’s catalog got the nod once more in the form of its billet-aluminum intake manifold. Both exhaust manifolds are driver side, high-flow cast-iron units from PPE, while Evan fabricated his own up-pipes to feed the remote mount turbo. The heads themselves incorporate LBZ-based fuel injectors.Much of the engine’s fuel system magic happens at the front of the block, where a billet-aluminum front cover from HSP Diesel accommodates dual CP3’s and a gear-driven fuel pump. The high-pressure pumps are S&S 10mm units, and the stroker CP3’s have no issue maintaining plenty of rail pressure for a set of S&S Ordnance injectors to use. In fact, Evan reports that rail pressure holds 180 mpa (26,100-psi) to 200 mpa (29,000-psi) throughout the course of a pull. On the low-pressure side, a Waterman fuel pump feeds the CP3’s a steady diet of 45-psi.Over the years, Evan has run turbos from Chris Beardsley, Hart’s and Wimer, and he told us he’s had great luck with all of them. “If there’s a turbo out there that pushes the limits, I’m gonna have it,” he told us. Evan’s current charger is this T6 Wimer unit, a turbo he purchased through Haisley Machine. The 3-inch smooth bore charger meets Limited Pro Stock diesel truck class rules but also allows the engine to make usable power throughout the rpm range. Evan fabricated the mount, collector, and hot piping with help from Street Carr Fabrication. The big Wimer sends 42 to 45-psi worth of boost through a Sandridge Custom air-to-water intercooler.An S&S supplied Bosch Motorsport stand-alone ECU, the old-school MS 15.1, controls the Duramax. Not surprisingly, in addition to building the engine, performing his own chassis work and driving the truck, Evan also handles his own tuning. It’s a skill he added to his repertoire many moons ago thanks to S&S Diesel Motorsport’s Andrew Stauffer showing him the ropes. “I tune using a pretty old version of Bosch software,” he admits. “It’s not the new stuff.” As far as his calibrations go, that’s classified. However, Evan did divulge that he spins the Duramax harder than most. “I turn mine harder than everyone else does. Think upper 4’s, lower 5’s, and upper 3,000s when spinning out on a good hook.” In case you’re wondering about the CORSA, Evan uses a separate data logger for chassis vs ECU.When it comes to getting power to the ground, all roads lead through here: a quick change transfer case (i.e. drop box) from Profab Machine. It’s part of the go-to hardware found in open driveline pulling classes (and believe it or not, they’re becoming more common in diesel drag racing). Up ahead of the drop box sits a one-speed reverser transmission, also from Profab. Initial engine-to-transmission power transfer begins inside a Probell blowproof bellhousing that conceals a four-disc clutch from Kenny’s Pulling Parts & Machine.You won’t find IFS under the front-end of Grey Area. Instead, a Ford Dana 60 sits in its stead, and it’s been fitted with a Detroit locker and chromoly axle shafts from Branik Motorsports. To limit the axle’s side-to-side and front-to-back movement, as well as ensure the front-end is always biting, Evan built the four-link system shown here. The combination of the four-link and two adjustable coilover Pro Shocks being present on each side means traction is never an issue, and that the Dana 60 rarely becomes unsettled.Like something straight off a Class 8 truck, a massive 20-145 Rockwell sits in the rear of Evan’s Silverado. The near-indestructible axle is another commonly used component in open driveline pulling classes, and it’s been reinforced courtesy of 300M Branik axles as well as being graced with a steel spool. If you were wondering about the suspension back here, there is none. The name of the game in sled pulling is to maintain the maximum allowed hitch height throughout the course of a hook. In Evan’s case, that height is 26-inches.When you’ve got friends in the machining business, having custom parts made is never out of the question. As a fan of Weld Sidewinders, Evan had JEB Modern Machines create a similar wheel, only in a 20-inch diameter. The unique forged wheels are fitted with Interco Trxus STS rubber, Evan’s tire of choice no matter the pulling surface. Each all-terrain measures 35×12.50R20, the maximum diameter DOT tire allowed in the Limited Pro Stock diesel truck class.One of the first things you’ll notice on Grey Area is that Evan kept it free of badges and stickers, which we think gives the Graystone Metallic Chevy an ultra-clean look. However, in the center of the tailgate, Evan made sure to give his friends at S&S Diesel Motorsport a well-deserved plug. “I couldn’t have done any of this without Andrew at S&S,” he told us. “Years ago, we built my Bosch harness on his kitchen table! Then during Covid, we made roughly seven trips to the S&S engine dyno, and one time we brought five different engines with us,” he continued. “We made some great gains and found more power at higher rpm. Andrew even turned the dyno over to us to run ourselves.”Without question, one of Evan’s most memorable moments behind the wheel of Grey Area took place in 2024 at Diesels In Dark Corners XIV. There, in the red Georgia clay, he built a 32-mph head of steam, moved the sled 336 feet, and came out on top in a 61-truck field. “We got done with harvest and had the time that year, so we went down,” he told us. “It was cool, and a humbling thing, really. It felt good to win it with my son there, and my team.” As for Evan’s team, you’ll find heavyweights in the truck pulling sport like Adam Hallien, Ronnie Hall, CW Cartmell, Matt and Garrett Loukes, and Grant Sterling in his corner. It’s common for all of them to meet up at events and pull together.Back in the Midwest (and especially his native Ohio), you can always find Evan and his Duramax in the hunt for a win. Over the years, Evan has won multiple Central Ohio Tractor Pullers Association (COTPC) championships, and he’s also come close to earning a Pro Pulling League trophy. However, Evan’s fondest memory was made at Dragway 42’s Cash Days event back in 2021, where he pulled off a clean sweep by winning both nights. But beyond the wins, the acclaim, and his uncanny ability to put a Duramax out front, Evan says it’s the human element that keeps him coming back for more. “It’s the people you meet in pulling, not the recognition you get for being successful, that make this sport so great.”
