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  • Socal Diesel 500hp 2003 Chevy Silverado 3500 Duramax Build - Max-a-Million

Socal Diesel 500hp 2003 Chevy Silverado 3500 Duramax Build - Max-a-Million

A Duramax built for the extra-long haul

Apr 3, 2015
Photographers: Courtesy Of ATS Diesel Performance
On the outside, Stephen Watson’s ’03 Chevrolet Silverado 3500HD looks like many other work trucks: a simple flatbed and an ARB front bumper, along with some meaty tires to battle the Carbondale, Colorado, snow are just about the only modifications done to the exterior. But Stephen, owner of Offroad Design, needed something tough enough to tow his fullsize offroad rigs to and from events without breaking a sweat (or breaking engine internals). Luckily for him, the crews at Socal Diesel and ATS Diesel Performance know how to build a million-mile Duramax.
Stephen, who bought the LB7 in 2007 with just 85,000 miles, understands broken components very well. Although the truck had a new engine and transfer case when he picked it up, hard use started wearing the Silverado down. A broken drive gear was the first sign of trouble on the truck, which usually sits unless it’s towing or hauling. Then, the injectors started showing signs of weakness, even after being replaced.
“It had injector problems to start with, and then it started sucking air, and one way or another, it ended up having one broken piston and cracks in a couple others,” Stephen says.
Stephen called his friend (and former Diesel Power editor) David Kennedy for advice on where to look for a new long-block, and after some research, Stephen’s white dualie was sent to Socal Diesel in Valencia, California, for a full engine build. Socal also balanced the South Bend dual-disc clutch with the engine, helping keep the driveline smooth and quiet.
Once the build was complete, the engine sat in a crate in Stephen’s shop for 18 months while he researched exhaust and turbo details. After getting the rest of the truck’s destiny sorted out, the engine was installed (with some special modifications, obviously) by Arvada, Colorado-based ATS Diesel Performance.
ATS, long known for its high-quality diesel performance parts, fitted the Silverado with its Aurora 4000 turbo kit, including the downpipe, turbo pedestal, turbocharger, and air intake. Other ATS parts included Pulse Flow exhaust manifolds and up-pipes and a Twin Fueler dual CP3 kit. The diesel performance guys also supplied EFILive tuning and a DSP5 five-stage tuning switch. Keeping everything running clean is a CAT fuel filter, adapted for the Duramax.
Since ATS is a few hours’ drive away from Stephen’s home, he wasn’t able to get as much time wrenching on his truck as he would have liked, but he says the crew at ATS did a great job sorting out the engine install.
Photo 5/18   |   The crew at ATS installed the Socal crate motor and added a few of their own signature products to keep the diesel breathing deep.
The truck’s name, Million-Mile Duramax, comes from the goals the team had with the truck’s engine build. The Chevy is primarily used as a tow vehicle, so it doesn’t need to make crazy amounts of power. Stephen resisted the urge to turn up the wick on everything, knowing reliability and useful torque were what he was really looking for.
“One of the things I had to keep an eye on was keeping the reins pulled in on everything,” Stephen says. “It’s so easy to make a ton of power on these that with everyone turned loose, we’d be making too much power. If you’ve got 800 hp, you don’t tow for very long.”
As it sits, Stephen’s truck makes about 550 hp as measured on the ATS dyno. That should be more than enough to get this 1-ton up the long, steep hills in Colorado’s Rocky Mountains. “It definitely cycles a lot of air through it,” he says. “The damn thing’s quick for a 10,000-pound truck. It straight runs.”
Once the truck was finished, the proud owner wasted no time putting it to good use. “The very first thing I did with it was haul three or four gigantic cords of firewood home, and that was very satisfying,” Stephen says. “It basically went to work immediately.”
Photo 6/18   |   Stephen says ATS sorted the Socal engine and a bunch of other parts and accessories to install the motor perfectly.
As with most projects, the Silverado isn’t finished yet. It still needs a few extra auxiliary gauges before it does any heavy towing, and Stephen’s had a few problems with the aftermarket clutch-pedal bracket installed by a previous owner. But once those little issues are sorted, Stephen says the truck will get to work, complete with his company’s logos plastered on the Silverado’s front fenders.
“We’ll be hauling all of our stuff out to King of the Hammers,” he says. “Offroad Design supports a bunch of teams out there, and we’ll probably have a 40-foot enclosed trailer behind the truck.”
We doubt the heavy Chevy will have any issues with that 1,900-mile drive, and Stephen seems to think the same thing.
“It’s kind of a blend of ATS’ airflow parts and Socal’s engine, and overall, it seems to be a good combination,” he says. “And it was a considerably cheaper solution than buying a new one, even with all of the modifications that have been done to the truck.”
Photo 15/18   |   Towing a 40-foot enclosed trailer appears regularly on the Silverado’s to-do list, so reliable power was a must. Stephen’s company hauls customers’ and race teams’ trucks and supplies all over the country.


ATS Diesel
Arvada, CO 80002
SoCal Diesel
Valencia, CA 91355



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