Building A Dual-Purpose GMC

Longhorn Fab creates a unique beast

August 2014 Feature Michael Deulley

When people enter the world of diesel, they walk into a lifestyle that is like none other in the automotive world today. There are limitless possibilities when it comes to incredible performance and savage power. Some drivers simply wish to own the stock power that is built into the truck during its manufacture, while others will never be satisfied with moderate strength and power. For Manfred Schreyer, owner of Longhorn Fab Shop, in Brookville, Ohio, the unquenchable desire for a coal-rolling monster led him and his team at Longhorn to craft a masterpiece of diesel machinery. While many others aim for the top-of-the-line in finesse and cutting-edge capability, not many come as close as the Longhorn 2006 GMC Sierra 2500 Duramax.

When Schreyer went on the hunt for a rock-solid truck, he wanted to make sure that the choice was well thought out and that it had a strong platform to handle the constant stress of work. At the same time, he and his crew had dirt drag racing in the agenda, so mixing bulletproof strength and head-spinning speed would be a tricky business. He found the '06 Duramax and saw the promise he was looking for. Immediately after buying the GMC, he began working on it before even bringing it home. Starting out of the gate the owner installed a 5-inch MBRP exhaust system. The new exhaust system gave the truck a little more growl and according to Schreyer, that's how it all began.

"Once you get a taste of that diesel rumble, you can't get enough," said Schreyer.

The GMC made its way to the Longhorn shop for a little bit of custom TLC. The team came together and installed a Longhorn Fab Shop EFILive tune, which is being switched by a prototype digital switch and is being monitored by an Edge Insight CTS. The next install slated was an EAS pyrometer and integrated dash pod. Schreyer then hooked up two dual-needle pressure gauges that would soon monitor air bag pressures for an impending air bag suspension system and two switches that would control compressor power to the air bags. Later, he placed four switches that would independently control each airbag at the four corners of the truck. The new installs gave Schreyer available monitoring for the next series of modifications that would undoubtedly overpower the truck and revolutionize his suspension.

Right The First Time

After all of the preparatory work was finished and on standby, Schreyer and the Longhorn team went after one of the biggest issues in any build truck, the transmission. Not taking any chances on an untimely failure of the transmission system, they decided to armor the GMC's system with a SunCoast GMAX 1000hp kit, which included a triple disc 1056 converter, upgraded billet shaft, SoCal billet SFI rated fled plates, ARP flex plate to crank bolts, Merchant Automotive T-case brace and toped off with a T-case rub kit. Why so overbuilt? Schreyer explained a flawless logic on the bear that is a transmission.

"We had the transmission torn down and we don't like doing things twice, so why not get it done right and never worry about it again?" said Schreyer.

Building On

With the transmission looking to be in great shape for installation, the build continued on. Switches were installed to govern the amount of pressure in the airbags located around the truck. The stock leaf springs were proven to be inadequate for their towing needs, but the airbags that replaced them were tried and true. A 4-link setup worked in concert with the airbags to give the truck the right amount of lift with whatever they towed. Whether the bed was loaded with Longhorn's custom fabricated parts, or the truck needed to haul a trailer, the truck could drive completely level with the help of their airbag suspension. With a custom-built set of A-arms in the front and height controlled with a simple switch in the cab, the Sierra could be manually adjusted at each corner, making it a truly one-of-a-kind suspension rig from Air Bag It. After the suspension was dialed in and ready to rock, Schreyer added a Fabtech heavy-duty tie rods and a PPE Pitman/Idler arm brace kit to help when they dropped the pressure out of the air bags and prepared for a nasty four-wheel drive launch during their drag races.

Turn Up The Power

With the suspension in the past, it was time to focus on the power. Under the hood, Schreyer and the Longhorn team put in their very own fabricated grid heater delete to increase air flow. Next, they installed an 85 percent over Industrial Injection CP3 pump and the air flow was even further increased with the addition of Screamin Diesel's high flow Y-bridge, which was powder-coated blood red. With all of the extra fuel being pumped through the GMC, keeping it cool was a tricky business. To mitigate heat issues, Longhorn's custom tunes helped, and with the addition of an MBRP downpipe and driver's side 3-inch boost tube, the truck inhaled a sufficient amount of cool air to counter the hard-charging engine. Schreyer and the team finished up under the hood with a PCV reroute, a PPE race plug and fuel rail, which prevents any premature fuel pressure relief and an AirDog II 200 to supply the CP3 pump ample fuel as well as keep outside air and dirt away from the fuel. Everything was about finished for this heavy-hauling, dirt-dragging beast, but a few last modifications would have to be done to ensure the best performance possible out of this GMC.

Finishing Touches

Going back to the outside, Schreyer decided to round the truck out by installing 2-inch Merchant Automotive wheel spacers, then had the wheels powder-coated black to fit the theme of the GMC's black scheme. He then had a fiberglass hood with a functional ram air scoop, custom mesh grille and blacked-out halo headlights and a Recon scanning twilight bar put on to make the truck visually stand out from other Sierras on the road. The fiberglass hood looked great, but Longhorn wanted the truck to stand out even more than normal, so they took the monster to Wintrow Signs in Greenville, Ohio, for a vinyl wrap-up of the hood, grille and rear window.

"There is no denying that it looks mean when someone sees it roll up in their rearview mirror," Schreyer continued. "Wintrow vinyl-wrapped the rear window so people knew who they just got passed by."

Everything on the Duramax had been finished just as Longhorn had intended and they couldn't be happier. From its humble beginnings that all stock trucks have, to its mind-numbing power overhaul, the Longhorn Sierra became the fast, hauling machine that Schreyer and the team needed. With painstaking research, the team was able to create something that few have seen and many admire and lust after. With the build behind them, the truck was back to work and geared up for whatever drag race lay in wait, ready to smoke the competition and possibly even haul the broken down competitors back to Longhorn Fab Shop for repairs.

For information regarding the products used in this feature, checkout our Aftermarket.

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