HIGH-CLASS CUMMINS

1,300 HP WRAPPED IN ’17 SILVERADO

Without a doubt, truck pulling is a remarkably dynamic form of motorsport. Pull order, changing track conditions, and the fact that it’s you versus 10, 20, or even 30 other competitors all makes predicting a winner nearly impossible. However, engine selection can greatly improve your chances of ending up out front. At the present time, that means campaigning a mechanically-injected Cummins. For years, Ryan Dedolph competed in the 2.6 class (now Limited Pro Stock) by way of Duramax power, but by 2016, he could see the writing on the wall: The GM V-8 simply couldn’t keep pace with the Cummins mills it was up against.

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Breathing new life into his puller, Ryan Dedolph set a ’17 body on top of his proven ’02 chassis for the ’17 season. The cab, fenders, and doors were all brand new GM overstock components. The bed was slightly used and a take-off item for a new HD being fitted with a service bed. With extensive man hours involved in the engine and body transformation, Dedolph was adamant that none of it would’ve been possible without the help of his friend, Chris Strobel, who took charge of the day-to-day operations of Dedolph’s shop, Rock Diesel, of Milton, Wisconsin, during the buildup.

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Pieced together at Skyline Diesel in Peosta, Iowa, a 6.7L Cummins block was filled, machined for cylinder sleeves, and fitted with a 1-inch deck plate. The main caps that secure the factory-based crankshaft are tied together via girdle, a set of billet rods connect to 12:1 compression, fly-cut Ross Racing pistons, and a Peterson dry sump oil system keeps 100 psi of oil pressure on tap. A thoroughly ported cast-iron 12-valve cylinder head from Hamilton Cams—fitted with oversize valves, dual-spring valve springs, and SMT Performance roller rockers—fastens to the block by way of 14mm head studs.

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At the center of the 1,300hp puzzle sits a P-pump from Prairie Performance. Equipped with 13mm plungers and barrels, it’s capable of flowing 1,000cc of fuel but is currently set somewhere between 700 and 750cc. Pump timing checks in just shy of 40 degrees. After being supplied 70 psi worth of fuel pressure courtesy of a gear-driven fuel pump, the 13mm unit sends pressurized diesel to a set of triple-feed, 5-hole injectors from Hart’s Diesel.

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Meeting Limited Pro Stock class turbo requirements is a smooth bore 3.0-inch, Garrett-based charger from Hart’s Diesel. It features a billet 76mm inducer compressor wheel, ball bearing center section, bolts to a T6 Steed Speed exhaust manifold, and produces 60 to 65 psi of boost. All intercooler piping was fabricated by Dedolph at his stop: Rock Diesel of Milton.

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No MyLink navigation, heated seats, or wireless charging here… The stripped down ’17 interior is void of everything but the essentials: hand throttle, driver seat, fabricated dash, data logger, and fuel, air, and water pump controls. The fabricated center console was built to accommodate the hand throttle, gear selector, and hang the fire extinguisher. Wilwood clutch and brake pedals also protrude through the firewall.

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A four-link front suspension system, utilizing DOM tubing, heim joints and custom cut brackets, keeps the Dana 60 located and the front wheels digging throughout the course of a pull. A pair of fully adjustable QA1 shocks positioned at each end of the Dana 60 allow Dedolph to tailor his upward and downward front suspension travel as he sees fit.

Being realistic about the environment he was competing in, Dedolph decided to drop a Cummins between the truck’s frame rails prior to the start of the ‘17 pulling season. At the same time, he wanted to give his ‘02 a fresh look. And with his build coinciding with the release of the redesigned ‘17 Chevy Silverado, the timing couldn’t have been more perfect. The new cab, doors, and fenders were sourced as GM overstock items and a lightly used bed was found locally, all of which were mated to a rolling chassis that’d already proven itself in the dirt.

ON DEDOLPH’S SILVERADO, A MASSIVE, ROCKWELL 20145 SITS IN PLACE OF THE FACTORY AAM 1150…

Cummins Power

Starting with a 6.7L Cummins block, the folks at Skyline Diesel treated it to a concrete fi ll, and machined it to accept cylinder sleeves, a deck plate, and 14mm head studs. A factory-based crankshaft, billet-steel connecting rods and fl y cut Ross Racing pistons round out the rotating assembly. A billet-steel roller cam, roller lifters and SMT Performance roller rockers lead to seamless valvetrain operation, while a fully ported 12-valve head from Hamilton Cams sits atop the block.

Mechanical Fueling

At the heart of the Cummins’ power making potential rests the Bosch P7100 that fuels it. Built by Prairie Performance, the competitionspec’d P-pump features 13mm plungers and barrels, can flow as much as 1,000cc of fuel, and is fed a steady, 70 psi worth of fuel pressure courtesy of a gear driven lift pump. In-cylinder fuel delivery is handled by a set of triple-feed, 5-hole injectors from Hart’s Diesel.

Big Boost and Chilled Air

Adhering to the 3.0-inch inducer, smooth bore rules of the Limited Pro Stock class, a turbo from Hart’s Diesel is employed. The Garrettderived, 76mm charger employs a ball bearing center cartridge, a T6 turbine inlet, and mounts to a Steed Speed exhaust manifold. In the midst of a pull, as much as 65 psi of boost is logged by the Computech data acquisition system. Intake temps check in at a cool 60 degrees thanks to a Precision Turbo & Engine PT3000 water-to-air intercooler.

Open Driveline

Thanks to open drivelines being permitted in the Limited Pro Stock category, driveline breakage and inconvenient downtime is a thing of the past. On Dedolph’s Silverado, a massive, Rockwell 20-145 sits in place of the factory AAM 1150 and a Dana 60 lives up front. An SCS reverser transfers power (sent its way via a four-disc Molinari clutch) to an SCS drop box. The truck’s lack of rear suspension keeps the rear end as rigid as possible, while a four-link front suspension limits the side-to-side and front-to-back movement of the Dana 60. QA1 adjustable shocks allow Dedolph to fine-tune the front end’s up-and-down movement.

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Once through the aforementioned drop box transfer case, power makes its way to the front and rear axles. Out back, a massive Rockwell 20-145—fitted with a fabricated differential housing, spool, and billet-aluminum hubs— absorbs most of the abuse, while a Dana 60 takes care of business up front. To survive the rigors of truck pulling, the Dodge-based Dana 60 benefits from a Detroit Truetrac, 38-spline axle shafts, and a free-spin heavy-duty hub kit from Dynatrac.

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For ultimate bite in the dirt, Dedolph employs six Nitto Mud Grapplers measuring 35-inches in diameter (315/75R16). Each aggressive ball of tread mounts to a lightweight, aluminum 16×10-inch rim from Real Racing Wheels.

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Thanks to a DataMaxx data logger from Computech, Dedolph is able to record vital information each pass down the track. Key parameters he monitors are: EGT in all six cylinders, intake air temp, oil pressure and temperature, and ground speed. To date, the data logger has recorded ground speeds as fast as 31 mph, and Dedolph tells us that EGT never exceeds the 1,600-degree threshold.

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With the weight box, weights, dry sump oil system components, fuel cell, and water-to-air intercooler onboard, somewhere around 2,000 pounds is positioned forward of the front axle. A direct benefi t of running the Precision Turbo & Engine PT3000 water-to-air intercooler is that the engine’s intake temp never exceeds 60 degrees. Ryan also disclosed that his water-to-air setup consumes 60 pounds of ice per hook.

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Despite only having a handful of hooks under its belt since being revised for the ‘17 season, Dedolph’s Silverado put 7 feet on the rest of the Limited Pro Stock field during Saturday’s qualifying session at the Scheid Diesel Extravaganza. A typical pull for the Rock Diesel of Milton Chevy entails the deck plated Cummins singing a 3,500 to 4,500 rpm song, the turbo producing 65 psi of boost, and the Mud Grapplers slinging dirt everywhere.

Despite getting a late start to the pulling season, Ryan’s re-powered and freshened-up GM still managed to amass several top five finishes and a few wins in 2017, along with a No. 1 qualifying effort at the Scheid Diesel Extravaganza. Over the winter, he plans to head back to the engine dyno and glean even more horsepower out of the deck plated Cummins. If Ryan finds the number he’s after, you can bet this will be one of the hardest charging trucks on the Limited Pro Stock circuit.DW

SPECIFICATION

’17 SILVERADO 2500 HD BODY, ’02 FRAME

OWNER: Ryan Dedolph
HOMETOWN: Milton, Wisconsin
ENGINE: 6.4L Cummins built by Skyline Diesel with a filled 6.7L block, main bearing girdle, cylinder sleeves, deck plate, billet-steel rods, Ross Racing fly-cut 12:1 pistons, billet-steel roller cam, ported Hamilton Cams 12-valve cylinder head with oversize valves, dual spring valve springs and SMT roller rockers, 14mm head studs
FUEL: Prairie Performance 13mm P7100, Hart’s Diesel triple-feed injectors
AIR: Hart’s Diesel Garrett-based 3.0 smooth bore turbo with 76mm compressor wheel, ball bearing center cartridge, T6 Steed Speed exhaust manifold, Precision PT3000 water-to-air intercooler
TRANSMISSION/TRANSFER CASE: SCS Gearbox reverser with 4-disc Molinari clutch, SCS drop box
HORSEPOWER: 1,300 hp (engine dyno)
TORQUE: 2,200 lb-ft (est.)
TIRES: 315/75R16 Nitto Mud Grappler
WHEELS: 16×10-inch Real Racing Wheels
AXLES/SUSPENSION: Rockwell 20-145 with SCS spool and billet-aluminum hubs, 4.56 gears (rear), Dana 60 with 38-spline axle shafts, Detroit Truetrac differential, Dynatrac Free-Spin Heavy-Duty Hub Conversion, 4.56 gears (front), Four-link suspension with dual QA1 adjustable shocks (front)