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A 1,000hp, 2.6 Smooth Bore Duramax

When Lee Stiltz replaced his V-10 Dodge with this ’05 Silverado 2500 HD his senior year of High School it was a definite upgrade. But just two years later, the ¾-ton Chevy was already being retired from daily driving duties. Since the truck pulling addiction took hold, Lee has embarked on an intense, six-year ride that’s brought him to the top of every pulling class he’s tried his hand in: Work Stock, 2.5, and now the 2.6 smooth bore category. In the truck’s current state, the LBZ Duramax under the hood belts out more than 1,000 hp and it rarely finishes outside of third place..

1,000+ HP At the Crank

When the 8,000-pound Pro Street (2.6 Smooth Bore) class was in its infancy, Lee was able to earn a points championship with an engine that dyno’d 880 hp. The year after that, he turned in a repeat performance with an 895hp combination. But not unlike other air-limited pulling classes, turbo technology took off in a big way last year—with Lee being the beneficiary of 120 more horsepower. His current parts recipe turned out 1,013 hp on the engine dyno…not bad for a 66mm smooth bore charger and cylinder heads that’ve hardly been modified.

Bottom-Up Build

Starting with an LBZ-based block at Diesel Technology Source, the water jackets were 75-percent filled with concrete and an internally balanced Ultra Billet crankshaft from Callies was fastened in place via ARP main studs. Forged Carrillo rods attach to fly-cut and thermal coated billet Diamond Racing pistons by way of Trend Performance H11 wrist pins, a custom grind alternate fire cam from DTS sits in place of the factory unit, and a Wagler pinned oil pump keeps ample Cen-Pe-Co oil circulating at full tilt. Slight massaging of the exhaust ports, SoCal Diesel beehive valve springs and billet rocker bridges were the extent of the mods performed on the heads, which are secured to the block by ARP Custom Age 625+ studs.

Custom-Tailored Fuel System

Working closely with the common-rail experts at S&S Diesel Motorsport, Lee was able to piece together an injection system that performs just as well on the track as it did on the dyno. Called its Ordnance LBZ Air Limited Spec injectors, the S&S units move torrents of fuel in a very quick manner, hence why only 1,200 to 1,300 microseconds of duration (commanded via tuning) is all that’s needed to make four-digit power. LLY rails, selected for their superior flow capabilities, store the pressurized fuel supplied by a dual CP3 arrangement that’s anything but ordinary. A 12mm stroker pump, dwelling in the factory location, combines forces with a reverse-rotation, belt-driven SuperSport pump that makes use of S&S’s new, gear-driven CP3-coupled fuel supply pump. Proper fuel filtration and supply pressure is achieved with the company’s brand-new regulated filter head assembly.

Hart’s Turbo

Stepping up to a T6 turbocharger from Hart’s Diesel has paid big dividends so far. As Hart’s always seems to do, this unit has outperformed all other 2.6-inch smooth bore chargers to date and Lee says he’ll be holding onto it for a while. The non-map groove, Garrett-based turbo makes use of a billet 66mm inducer compressor wheel, a dual ball bearing center section, and a sizeable turbine wheel inside a relatively tight, 1.00 A/R exhaust housing. The T6 flange charger mounts to a Wehrli Custom Fabrication T4 pedestal and exhaust collector through the use of a T6 to T4 adapter and sends boost through a Bell air-to-air intercooler via Wehrli piping. The velocity stack and air guillotine came from Show-Me Performance.

Sled-Ready Allison

No amount of horsepower is worth making if you don’t have a transmission that can hold it, so Lee turned to the Allison gurus at Illini Outlaw Diesel to prep his transmission for battle. All billet shafts, a billet C2 clutch hub, Raybestos clutches, and a 3,200-rpm stall Sun Coast converter all got the call, along with a Fleece Alli-Locker for precise control over lockup and a Merchant Automotive rear housing support for exterior reinforcement. With the truck’s 4.56 ring and pinion, Lo side selected in the transfer case, and 900-ish horsepower making it to the ground, Lee has no problem carrying fourth gear all the way down the track.

A Constant Contender

The Pro Street class is one of few remaining precincts in truck pulling where the competition isn’t largely dominated by Cummins. And in working with some of the biggest names in the Duramax world, Lee aims to keep it that way. One of the busiest pullers we’ve met, Lee has already accumulated more than 300 hooks in the truck’s first six years of action. And with that experience has come many wins, including two Pro Street points championships in the Illinois Tractor Pulling Association, as well as two Work Stock titles and one 2.5 class championship in the United Pullers of America organization. Throw in a Third Place finish at the 2019 Scheid Diesel Extravaganza and a Second at Diesels in Dark Corners and you’ve got a Duramax that’s highly competitive on the national level. With both of those aforementioned events still on the books for 2020, be on the lookout for this hard-charging Bow Tie in Pro Street. Chances are good you’ll find it somewhere beyond the 300-foot mark.