A Single-Turbo Duramax That Hits 127 MPH

A 1,000-hp, 10-second Duramax Street Truck

It’s no secret that diesels make great allaround vehicles that can also haul the mail. Looking at Scott Matthew’s ’05 GMC 2500, we could see the all-around usefulness, but not the speed part. After all, it’s only got a single turbocharger, no nitrous, and is a full-weight 6,800-pound street truck.

“10.90 AT 127MPH”

A Single-Turbo Duramax That Hits 127 MPH — The deceptively simple 6.6L Duramax in Scott’s ’05 GMC puts down a whop- ping 950-1,000 rear-wheel horsepower despite having just a large single turbo and no nitrous oxide. A long block built by Diesel Addiction was a big key in making that type of reliable power.

Approximately 55 psi of boost is generated by the 80mm inducer single turbo, which is a very efficient design from Bullseye Power. Drive pressure and boost are almost a 1:1 ratio, which indicates the turbocharger is very well matched to the engine’s level of performance.

KEEP IT SIMPLE STUPID

Well, as of right now, Scott’s best time is a 10.90 at 127 mph, which ﬁrmly cements him in the 10-second zone, as well as the 900 to 1,000 horsepower range. He also bracket races the truck at both diesel and non-diesel events, and has even won a few of them. So the question remains, how was he able to build a truck that was so simple, yet so fast?

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Blown intercooler boots are no fun and can result in a bad day at the track (or behind a trailer) so the stock boots throughout the intake system were replaced with performance versions from Vibrant Performance.

STRONG FOUNDATION

Before anything else came reliability, as having a fast bomb wasn’t in the plan for Scott. With a four-digit power goal in mind, he set about building the 6.6L Duramax engine into a solid foundation for power. The engine was assembled by Diesel Addiction out of Wilmington, North Carolina, and features only the best in parts. The block and crank are stock, but that’s about it for the bottom end. The factory connecting rods are suspect at high power levels, so they were replaced with Carrillo rods, which were connected to Mahle cast pistons. ARP studs were used to secure both the main caps and heads, and an ATI balancer helps balance crank harmonics. The valvetrain was also upgraded with a camshaft from Hamilton Cams, as well as pushrods and valvesprings also from Hamilton.

For maximum power potential and reliability, Scott chose to add a second CP3 pump that works in con- junction with the existing pump in the valley of the engine. With enough fuel capability for 1,100-1,200 horsepower, the twin pumps and Exergy Engineering injectors more than get the job done.

At first we didn’t see a lift pump, but it’s there, just hiding behind the stock frame rail. With some careful tuning from Diesel Addiction, the single lift pump was all that was needed to support power into the four-digit range.

Both the front and rear axles of the truck have been upgraded for survival at the dragstrip. Up front, a set of Rare Parts tie-rods and PPE centerlink handles the power, while the rear axle is planted with the help of a set of Diesel Addiction traction bars.

AIR AND FUEL

Airﬂow and fueling throughout the engine were also upgraded with an impressive array of parts. From the engine, exhaust travels through high-ﬂowing PPE exhaust manifolds, and into a T4-ﬂange turbo pedestal from ProFab Performance. The compressor is a single 80mm turbo from Bullseye Power, with an 87mm turbine wheel and 1.10 A/R exhaust housing. A custom 5-inch intake from Diesel Addiction feeds the big S400, while an ATS downpipe and custom exhaust rounds out the airﬂow package. On the fuel side of things, Scott decided to keep things simple and power-oriented, just like with boost. From the tank, fuel is pushed up to a PPE Dual Fueler by an Airdog 165gph lift pump, which then feeds a set of 100-percent over injectors from Exergy Engineering.

“SOMETIMES A SIMPLE SETUP AND OUTLANDISH PERFORMANCE DO GO HAND IN HAND”

At the track, Scott takes no chances, monitoring fuel and oil pressure via Isspro gauges in between rounds, to make sure everything is A-OK.

A Single-Turbo Duramax That Hits 127 MPH

POWER TRANSMISSION

While Scott had the recipe for power, he knew the factory transmission was hopelessly outmatched, and again turned to Diesel Addiction for help in making the GMC dragstrip ready. A Suncoast Diesel Transmissions Stage 4 kit was ordered, along with a billet input shaft, and a 1058 Suncoast triple-disc converter that would allow the big single turbo to spool. Finally, a BT Dieselworks Lockup Box was added, so Scott has full control of lockup at the dragstrip.

Scott has stepped up his game to M&H slicks for track use, but for the street, 20-inch RBP 94R wheels and 305/50R20 Nitto 420S tires keep the truck stuck to the pavement rain or shine.

TUNE AND TEST

With EFILive tuning from Diesel Addiction, Scott hit the track and put down some very impressive performances. With 20-inch street tires, the four-wheel-drive truck clicked off low 11s with a best of 11.30, at more than 120 mph. With a 10-second timeslip in reach, Scott dropped some weight by removing all the seats and added M&H racing slicks. Right before we went to press, the dangerous Duramax clicked off a 10.90 at 127 mph, nabbing Scott that 10-second time slip, and proving that sometimes a simple setup and outlandish performance do go hand in hand. DW

A Single-Turbo Duramax That Hits 127 MPH