'03 Chevy Silverado 2500HD LB7

’03 Chevy Silverado 2500HD LB7

While most enthusiasts eventually part ways with their first diesel, a select few hold onto them for practically forever. For these holdouts, their first diesel represents the first time they realized how easy it was to add horsepower, tow whatever they wanted, and still get respectable fuel economy. Matt Berlemann bought his ‘03 Chevy Silverado 2500HD to do all of these things. From the time it had 16 miles on the odometer it’s been programmed, lifted, towing anything he’s needed it to, and knocking down more than 21 mpg on the highway when empty.

“By the end of the quarter mile I had him by about 2½ car lengths.” —Matt Berlemann on racing a ’13 Corvette (from a 35 mph roll)

All ECM and TCM tuning was handled by the EFI Live experts at DuramaxTuner.com. And being that LB7 and LLY trucks can utilize the popular Edge Insight CTS monitor to change tunes on the fly, no DSP5 switch was required. In our ride along, the truck planted our heads firmly against the headrests from 0-120 mph and we saw 73 psi of boost. Not bad for having an even hotter tune left in the truck’s arsenal… — All ECM and TCM tuning was handled by the EFI Live experts at DuramaxTuner.com.
And being that LB7 and LLY trucks can utilize the popular Edge Insight CTS monitor to change tunes on the fly, no DSP5 switch was required. In our ride along, the truck planted our heads firmly against the headrests from 0-120 mph and we saw 73 psi of boost. Not bad for having an even hotter tune left in the truck’s arsenal…

The LB7 Duramax under the hood of Matt Berlemann’s ’03 Silverado sports Carrillo rods, coated 0.020-inch over Mahle Motorsport cast-aluminum pistons, keyed crankshaft and camshaft, polished factory heads with Diesel Technology Source valve springs, and ARP’s Custom Age 625+ head studs. Flynn’s Shop of Alexander, Illinois, handled assembly of the long block. — The LB7 Duramax under the hood of Matt Berlemann’s ’03 Silverado sports Carrillo rods, coated 0.020-inch over MAHLE Motorsport cast-aluminum pistons, keyed crankshaft and camshaft, polished factory heads with Diesel Technology Source valve springs, and ARP’s Custom Age 625+ head studs. Flynn’s Shop of Alexander, Illinois, handled assembly of the long block.

FORCED HAND

But after racking up 240,000 trouble-free miles, the injector failure that LB7’s are notorious for finally sidelined the truck in the summer of 2013. With his Silverado waiting to be repaired at Flynn’s Shop in Alexander, Illinois, Matt started kicking around the idea of adding more power. “I knew I needed injectors, the turbo was old, my weak links were the rods and transmission, so I thought hell, let’s build it right and be done with it,” he told us.

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ENGINE WORK

With orders to build a bulletproof drivetrain, the guys at Flynn’s got to work on the Duramax mill under the hood. The original block was fitted with Carrillo connecting rods, which employ ARP rod bolts, Mahle Motorsport coated stock replacement pistons, and a brand new OE spec camshaft. Coated main, rod, and cam bearings were utilized, as well as a set of ARP main studs.

The bulletproofing continued by keying both the crankshaft and camshaft, and in order to keep the factory water pump from failing at higher engine speeds the drive gear and impeller were TIG welded to the pump’s shaft. Up top, the heads were polished, and then fitted with Diesel Technology Source valve springs. From there, factory head gaskets and ARP Custom Age 625+ head studs finished off the long block’s list of hard part upgrades.

Kicking the passenger side battery out of its original location is this billet S480. It features the common 96mm turbine wheel, T6 flange, and 1.32 A/R turbine housing combination. In conjunction with the billet S366, the compound setup produces between 70-75 psi of boost on the street.

Opting for a compound turbo arrangement called for sizing a high-pressure turbo that could survive a fair amount of drive pressure yet flow well up top. The answer was this T4 flanged, billet S366. It’s built by Engineered Diesel and was included in the Wehrli Custom Fabrication Big Twin kit Matt purchased.

BIG FUEL

On the fuel side, a set of 100 percent over injectors from Exergy Performance offer the potential to make in excess of 900 hp yet can be tuned to make a smoke-free 700. A Dual Fueler CP3 system from PPE ensures adequate rail pressure is always on tap for the injectors to use. Not leaving anything to chance, a 260-gph Titanium series lift pump system from FASS—coupled with a Bean’s Diesel fuel tank sump—has no problem keeping the CP3’s supplied with plenty of low pressure fuel.

Built by the Allison experts at Flynn’s, a bulletproof five-speed A1000 was put together using Sun Coast parts. A GMax 5-pac clutch kit, billet input and output shafts, 1058 triple-disc torque converter with a billet front cover, and a billet flex plate were employed. Because Matt would occasionally be towing with the truck, the guys at Flynn’s also installed a PPE transmission cooler. To date, ATF temps are yet to crest a cool 150 degrees.

To keep the rear AAM1150 from rotating, Matt built a set of 1.25-inch (ID) stainless steel traction bars, along with bolt-on frame and axle mounts. Knowing he might twist the factory 0.60-inch wall rear driveshaft in half with the added power, Matt also upgraded to a 0.140-inch wall, high strength aluminum unit.

With 100 percent over injectors from Exergy Performance to feed, a PPE Dual Fueler CP3 kit was installed. Matt sourced both brand new pumps from his local GM dealer. An LB7 CP3 sits in the factory location, with an LBZ pump getting belt driven up top.

Thanks to a 260-gph Titanium series FASS system, there is no shortage of fuel supply making it to the CP3’s. This system can support trucks making up to 1,500 hp.

366 OVER 480

Sized with room for future growth, Flynn’s installed a complete compound turbo arrangement from Wehrli Custom Fabrication. Called its Big Twin kit, the Wehrli setup uses an S366 BorgWarner in the valley, and an S480 in place of the passenger side battery (which was relocated along the frame rail). Both chargers feature billet compressor wheels—helping them to spool quicker and flow more air up top than their cast wheel’d cousins. A 3-inch diameter, high flow Y-bridge, 3-inch hot side and cold side pipes also accompany the turbo kit. Helping to cool EGT and stand up to big boost is an aftermarket intercooler from Mishimoto.

“Both chargers feature billet compressor wheels—helping them to spool quicker.”

TRANSMISSION

Known for building indestructible Allison 1000 transmissions, the guys at Flynn’s wasted no time tearing into the 240,000-mile stocker and making it four times stronger. Employing a Sun Coast Gmax 5-pac, billet input and output shafts, a 1058 triple disc converter and billet flex plate, this Allison has no problem harnessing the torque being created by the potent LB7 in front of it.

Instead of pulling fuel from the top of the factory tank, Matt chose to run a sump. The Bean’s Diesel sump kit is one of the most popular products in the diesel industry, and even comes with the 3-inch hole saw needed to install it.

Fabtech HD tie rods replace the failure-prone factory units up front. The Fabtech units are nearly three times the size of the stockers.

Further strengthening the truck’s steering system is a center link from PPE. Made from solid 304 stainless steel, the 1.5-inch diameter center link rules out the need to use pitman and idler arm braces.

Still sporting the original paint, Matt’s LB7 is about as clean as they come. It might have a quarter of a million miles on the clock, but it’s been meticulously maintained over the last 13 years.

DURAMAX TUNER

Tying the overall package together was left to DuramaxTuner.com. Through use of EFI Live software, their carefully crafted tuning files have made a 900hp, 13-year-old truck extremely drivable, well mannered, virtually smoke-free, and a blast to drive. “It cleans up so fast, you don’t even know it’s a diesel until it blows by you,” Matt told us.

“A set of 100 percent over injectors from Exergy Performance offer the potential to make in excess of 900 hp.”

If there’s one thing we picked up in talking with Matt, it’s that he expects his truck to do a little bit of everything. That means when it’s time to hunt, you’ll find it somewhere out in the mud, snow, and timber. When it’s time to haul horses, it’s getting hooked to the trailer. And when it’s time to run down to Florida and back, it’s full steam ahead. So while we’re not sure if he’ll use his truck for commuting, road tripping, towing, or as a Corvette killer, one thing’s for sure: the next quarter-million miles of this Chevy’s life will be a lot more entertaining. DW

Reinforcing the tail housing of the Allison 1000 is this transfer case brace from Merchant Automotive. While the transmission was being built, Matt also had one of Merchant’s transfer case upgrade kits installed to eliminate the infamous “pump rub” scenario from ever occurring.

A trusty BFGoodrich All-Terrain, measuring 305/55R20, sits at each corner, although they have a hard time maintaining traction in two-wheel drive. For wheels, Matt chose to run 20x10 Bison SS8’s from American Force. — A trusty BFGoodrich All-Terrain, measuring 305/55R20, sits at each corner, although they have a hard time maintaining traction in two-wheel drive. For wheels, Matt chose to run 20×10 Bison SS8’s from American Force.

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Tech Q&A Part #6

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Mike McGlothlin and Surajpal Singh Bisht

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