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  • The Bear Edition: 1,236hp 2007 GMC Sierra 2500HD

The Bear Edition: 1,236hp 2007 GMC Sierra 2500HD

The Bear Edition

Aug 22, 2017
Photographers: Brian Hollingsworth
You’ve got the brown bear, the polar bear, the Asian black bear, the American black bear, the sun bear, the sloth bear, the spectacled bear, and, last but not least, the giant panda. Formidable animals indeed, bears stand intimidatingly on their hind feet and can climb, tear, and catch with the upmost finesse using their massive nonretractable claws and acute sense of smell. They are mostly solitary (minus the whole mom and cub thing) and prefer keeping their territory clear of competition and neutralizing anything that threatens their dominance over shooting the breeze at the local berry tree.
Photo 2/92   |   Bear Edition 2007 GMC Sierra 2500HD Rear
Well, there’s a new bear in town, and it comes in the form of the mechanically beautiful 1,236hp ’07½ GMC Sierra 2500HD owned by Trent Clark of Calgary, Alberta, Canada—and it just might be the fiercest animal yet. It’s advisable for rivals to just collapse and play dead, because there’s no fighting back, defending against, or outrunning this beast. Trent’s truck really is the alpha truck, epitomizing a machine that basically rules in the areas that count most: performance and looks.
Photo 3/92   |   Bear Edition 2007 GMC Sierra 2500HD
We know the story all too well, and what was supposed to be a moderate build escalated into a legit eight-year investment in time, money, resources, and patience. Like so many other truck enthusiasts, Trent is in the construction industry and needed a truck capable of pulling a trailer. He assumed the lease of the perfectly stock 2500HD in 2009 from a friend who opted for a BMW, with the intention of a simple tune for slightly better performance. Like most of us who can’t just leave our trucks alone, he soon wanted a slightly more aggressive look and selected a 6-inch lift, custom wheels, bigger tires, and fender flares. The terminal disease for more power flared up again, resulting in a second turbo, head studs, and a mild ATS transmission, followed up by an Edge monitor, straight-pipe exhaust, SSBC brakes, and 100-percent-over injectors.
Photo 4/92   |   Bear Edition 2007 GMC Sierra 2500HD Engine
When the engine kicked the proverbial bucket, a SoCal Diesel–built Duramax was quick to fill the void. It seemed fit to handle more air and fuel, so mods including a triple-turbo setup, two-stage NOS system, and 150-gph FASS system were installed. Since more is not always better and the triple turbos turned out to be quite underwhelming, Trent sent the sick truck to the doctor: Rob Coddens (“Idaho Rob”) of Adrenaline Truck Performance in Meridian, Idaho. The triple-turbo setup was kicked to the curb in favor of a new compound-turbo setup consisting of 106mm and 68mm Garrett ball bearing turbos. Focusing on the looks side of the equation, Trent chose to up the ante again with a powdercoated 8-inch Bulletproof Diesel lift kit, American Force wheels, Nitto tires, fabricated step sides, a partial exterior wrap, and a complete Hertz audio system.
Boom went the engine, yet again; it’s a vicious cycle, indeed. Enter Curtis Halvorson of Extreme Engine Development in Calgary, enlisted by Trent to further outfit the truck’s SoCal Duramax with higher-horsepower performance parts. Trent promptly managed to thrash up the ATS-built transmission, which was evidently the newest weakest link. Billet input, output, and intermediate shafts and a billet flywheel helped remedy the transmission ails, while an oversized spring and Stage 6 PPE Clutch Pack made for one robust transmission—which Trent managed to pulverize. And again after that. Finally, Commercial Powertrain came to the rescue with its 2,000hp warranty and custom clutch kit and valvebody.
Photo 5/92   |   Bear Edition 2007 GMC Sierra 2500HD Hood
The proverbial smoke was just clearing from the nasty burnout produced by the Duramax’s fresh performance engine build and super wah-zoo transmission when disaster struck again: a rowdy injector resulted in yet another cracked engine block and a broken crankshaft. Curtis Halvorson upped the game by stuffing high-performance internals into the LMM’s rebellious and ravenous belly. Fueling upgrades included custom Dynomite Diesel Products (DDP) 275-percent-over injectors and a 12mm Exergy fuel injection pump to replace one of the stock CP3 units.
With the engine carnage finally over (knock on hood), Trent could return to the “show truck” aspect: custom airbrushing by longtime 8-Lug friend Mike O’Brien at MOB Airbrush (remember the column we used to run called MOB Scene?), a 12-inch Bulletproof Suspension lift, a custom audio enclosure in the bed, and many interior upgrades, which you can check out in the SpecSheet.
Photo 6/92   |   Bear Edition 2007 GMC Sierra 2500HD Bed
Trent uses the truck for client promotions, taking it to corporate events as appropriate. In addition to its regular duties, it’ll be seen at some dyno competitions and also a variety of shows across North America. Hopefully, Trent can enjoy his show-’n’-go (his two favorite parts of the truck) concoction without too much more heartache, hitting high power numbers and hauling copious show trophies.

SpecSheet

Year/Make/Model: ’07½ GMC Sierra 2500HD
Owner: Trent Clark
Hometown: Calgary, Alberta, Canada
Engine: Bored and blueprinted 6.6L Duramax V-8; SoCal Diesel forged, cut, and coated pistons; Carrillo forged rods; chromoly pushrods; ARP 625 head studs; Stage 2 CNC ported Dmax cylinder head assembly with titanium retainers; O-ring cylinder heads; billet internally balanced crankshaft; custom-designed Stage 3 Extreme Engine Development (EED) camshaft; ERP main cap oil modifications; custom valvesprings and chromoly retainers; rocker stud kit; billet caps and SoCal Diesel main girdle kit; SoCal rocker stud kit
Transmission: Custom-built by Commercial Powertrain; billet P2 planetary; Goerend converter with billet stator; billet input, output, and intermediate shafts; billet flywheel; Commercial Powertrain detailed valvebody and clutch kit
Odometer: 150,000 kilometers (1,200 miles on engine)
Induction: Compound-turbo setup with wastegated Garrett ball bearing 55/41 turbo and Garrett ball bearing 40/94 turbo with exhaust housing modification to 68MM; DDP 275-percent-over injectors; two-stage ZEX nitrous system with four 10-pound bottles capable of max 2x300hp shots, remote bottle openers, four solenoids, custom bottle mounts, and custom-fabricated NOS purge system
Exhaust: Custom-fabricated 5-inch straight pipe off of secondary turbo, tipped to 18-inch Lambo-style exit in center of rear bumper
Fueling: Dual injection pumps consisting of a custom 12mm Exergy and a stock PPE CP3; PPE Dual Fueler kit; FASS 220-GPH lift pump
Engine Management: Custom EFILive tuning by Rob Coddens
Horsepower/Torque: Fuel only: 1,236 rwhp (1,300 rwhp goal); Nitrous estimate: 1,900-plus rwhp
Suspension: 12-inch Bulletproof Suspension kit, dual mount system, twin Fox shocks, and custom traction bars (not photographed: 16-inch coilover lift with a front axle swap)
Interior: Billet push-button control panel mounted in custom center console; three performance custom-mounted gauges in center of upper dash; Roadwire leather seats; suede headliner; custom-painted trim pieces; custom speaker enclosures on door panels and audio system; Grant steering wheel; Edge Insight CTS data monitor; Alpine backup camera; Hertz sound system and custom fabrication by Mobile Solutions that includes a Hertz HDP five-channel amplifier, two sets of Hertz Hi-Energy front and rear speakers, two Hertz 10-inch subwoofers, Pioneer receiver, and two video monitors with built-in DVD capabilities
Rear End: Bored axlehousings; Yukon Axle (10.5/11.5 38-spline); 4:56 gears
Exterior/Accessories: Front and rear SSBC oversized brake package; Front and Rear Fusion bumpers; 3 sets of Dual LED Rigid Industries flush mounted cube lights in front and rear bumpers; 12-inch Rigid light bar in front bumper; Retrax tonneau cover; fender flares; Amp Research XL steps; Monster Hooks; hooped drive line; BedRug; Front and rear Lazer Shifters; custom grille; NOS purge tubes over cowl; underhood mirrors; custom “The Bear” plate on frame; Mag-Hytech differential and transmission covers; Rigid Industries lighting on undercarriage and in wheelwells; Custom Recon lenses and etched halos in headlights; custom painted taillights; rock lights in bed; custom purple lighting in NOS purge tubes; Hertz Sound System in bed with custom fabrication by Visions that includes two Hertz HDP 5-channel amplifiers and an H8 Digital Signal Processor, two Legend Hertz Hi-Energy, two Hertz 8-inch subwoofers
Paint/Wrap: Grizzly and winter mountain airbrushing by MOB Airbrush; black base paint and clear by DiVita Auto Design; protection film over entire truck; purple ZEX-colored powdercoating on engine components, suspension, axles, frame, and lugs
Wheels: 22x14 American Force SS8 Recon (not pictured: 26x14 Kompression)
Tires: 40x15.5R22 Nitto Mud Grapplers (not pictured: 42-inch Fury Country Hunter M/T)
Special Thanks: Castle Customs, DiVita Auto Designs, Trigger Industries, and Kompression Wheels
Fun Fact: The Bear is the current and repeat Best Overall award winner for Driven – Calgary (largest event in the west outside of Vancouver) and as a result is no longer eligible for even a chocolate bar in Driven. The Bear is also the current and four-time Best in Class winner at The World of Wheels – Calgary.

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