Crank Windows and 650 HP

A lot of us remember that pivotal moment when a diesel captured our undivided attention for the first time. For Kaden Nelson, that moment occurred at a local truck pull: “Some guys came from out of town and cleaned house at my county fair’s annual sled pull. From there on, I was into [diesels],” he told us. A decade later, Kaden uses this 650-hp LMM Duramax to get to and from his day job and as a workhorse around the farm; he even occasionally competes in area truck pulls and drag races.

“Kaden made the call to see how far he could push the factory pistons”

FIRST STEPS

Since buying the ’09 GMC Sierra 2500 HD, getting the truck to its current state has been a gradual yet perpetual process. He turned to a nearby diesel performance shop, Randall’s Performance, for a helping hand and sound advice throughout the build. Kaden got started by installing a factory driver-side exhaust manifold from an LML, followed by a set of analog gauges from Auto Meter.

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At the 8,000-mile mark, a TransGo Jr. shift kit graced the Allison automatic, and both the ECM and TCM were tuned via EFILive. Next it was time for a lift pump, so a 165-gph AirDog II fuel system was bolted on. Over time, an Industrial Injection bag of parts would be installed in the CP3, and a 2.5-inch stock-appearing turbo from Danville Performance would also make its way onto the truck. Then, it was time to dig into the engine for the first time.

BIG POWER PREP

With plans to add larger injectors, a higher volume CP3 and compound turbos, Kaden decided to have the guys at Randall’s pull the heads and install ARP head studs. However, while the heads were off, Kaden talked himself into a Stage 1 Street Tow cam from Empire Diesel Performance. Complementing the cam, a set of 110-lbs Comp Cams valve springs were fitted to the heads for adequate valve seat pressure.

It was at this time that Kaden made the call to see how far he could push the factory pistons, being that this is the biggest internal weak link on LMM (and LBZ) Duramax mills. “I know I’m playing with fire,” he told us. He then added that one day the truck will boast a built motor with a lot more fuel and air.

The potent LMM Duramax under the hood of Kaden Nelson’s ’09 GMC Sierra 2500 HD sports a set of Exergy Performance 45 percent over injectors, Exergy Performance 10mm stroker CP3 and an AirDog II 165-gph fuel system. While many would consider this excessive for stock LMM pistons (which have been known to crack at power levels beyond 600 hp), safe tuning, courtesy of Rob Coddens at Adrenaline Truck Performance, has kept the engine together for more than a year at the 650-rwhp mark.

A compound turbo arrangement from Wehrli Custom Fabrication makes the truck extremely fun to drive. The setup utilizes a T6 flanged billet compressor wheeled BorgWarner S475 as the atmospheric unit (shown).

Tucked away in the factory location rests the first aftermarket turbo Kaden purchased: a 2.5-inch (63mm) charger from Danville Performance. The stock appearing VGT Garrett is the key to the truck’s quick spool up, and when combined with the S475 mounted in front of it, 55 psi of boost is made at full tilt.

In the cab, Auto Meter boost and pyrometer gauges keep an eye on what both turbos are producing and EGT. Thanks to a Banks Techni-cooler replacing the stock intercooler, exhaust temps stay in check, with the hottest reading to date being 1,550 degrees Fahrenheit. And yes, those are crank windows. This truly is a workingman’s truck—built to do a little bit of everything.

With the billet S475 taking the place of the passenger side battery, it had to be relocated. Conveniently, the Wehrli Custom Fabrication compound turbo kit came with a battery tray that effectively mounted it to the passenger side frame rail.

Kaden’s good friend, Jon Elliott, built the traction bars harbored under the truck. Made with heavy-duty Schedule 80 pipe, they haven’t skipped a beat so far—surviving their fair share of sled-pull and drag-strip abuse.

BIG FUEL AND AIR

Stepping up his fuel game, Kaden opted for a set of 45 percent over injectors from Exergy Performance and ditched the modded factory CP3 in favor of a 10mm stroker pump, also from Exergy. Upsizing on the air side, he retained the 2.5-inch Danville charger in the valley but added a billet S475 atmospheric unit in front of it. All the plumbing and parts to make the compound turbo system work came from Wehrli Custom Fabrication, as did the S475 charger.

TRANSMISSION WORK

As you might’ve imagined, at this point, a lot more resides inside the Allison 1000 than a shift kit. To handle the newfound power and torque, an MA700 transmission from Merchant Automotive got the nod. It features a billet, triple-disc converter, an increased clutch count with upgraded clutches and frictions, as well as billet input and output shafts.

END RESULT

Before Kaden’s truck left Randall’s care, it was strapped to the company’s in-house chassis dyno. There, it was confirmed that 646 hp and 1,055 lb-ft of torque was making it to the rear wheels. On the street, 55 psi of boost can be observed under wide-open throttle, and, thanks to the 63mm/75mm turbo configuration, spool up is quick, yet the power band is extremely smooth.

In this dyno graph you can clearly see that Kaden’s tuner, Rob Coddens of Adrenaline Truck Performance, knows the danger in making 650 hp on stock LMM pistons. Notice that peak torque is made at 3,000 rpm rather than at a much lower engine speed. This is done to keep cylinder pressure down (timing is ramped up progressively as rpm rises). While 1,300 lb-ft of torque could be made at 2,000 to 2,500 rpm, there is no telling how long the pistons would survive it. We like seeing smart tuning like this.

Perhaps the best part about Kaden’s truck is that it doesn’t sacrifice drivability or (better yet) reliability at this power level. He can hop in it and go to work, hook it to a trailer, pull a sled or hit the drag strip without a second thought. It’s drivable, dependable and powerful: Sounds like the ultimate daily driver to us! DW

Fun Fact: Kaden took an interest in diesels when he witnessed some nasty, out-of-town pulling trucks clean house at his county fair. Four short years later, he would graduate from UTI with a degree in Diesel & Industrial Technology.