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Seffner, Florida is home to a unique drag truck that embodies the spirit of family heritage and high-performance engineering. Wyatt Stengel’s 1970 GMC K15 is a cherished family heirloom, and has undergone a remarkable metamorphosis into a drag racing powerhouse thanks to an upgraded LB7 Duramax engine.
Stengel has documented much of his journey building the diesel truck on his personal YouTube channel, as well as being a frequent contributor and cohort on the popular BoostedBoiz channel. The four-year project culminated in a pretty unique build that blends aesthetics and horsepower. Stingel even competed with the K15 at the Ultimate Callout Challenge and joined the ranks of some of the fastest Duramax race trucks out there.
At the core of the K15’s transformation is the formidable ‘03 LB7 Duramax engine, which is more than capable of robust performance. Stingel’s LB7 makes a cool 1,300 horsepower at 4,000 rpm and an impressive 1,900 lb.-ft. of torque at 3,400 rpm. Wyatt’s expertise and commitment to pushing the boundaries of diesel power are evident in the meticulous upgrades applied to the Duramax powerplant.
The engine’s internals received a comprehensive overhaul, featuring a crankshaft from Callies, Carrillo rods, and Mahle forged pistons. A modified stock oil pump and oil pan ensure optimal lubrication, while a stage 2 alternate firing order camshaft and DHD high rpm water pump contribute to the enhanced performance as well. The fuel system underwent a transformation with components like an NCC Fab water-to-air intercooler, a VSRacing 85mm turbocharger boasting 75 psi of boost, and an Exergy Performance 14mm CP3 injection pump. Additionally, 250% over injectors from Exergy Performance amplify the diesel prowess even further.
To add yet another extra kick, Stengel incorporated a Nitrous Express system, delivering a 400-horsepower boost when needed. The seamless integration of nitrous oxide complements the Duramax’s raw power, providing an additional layer of acceleration and performance on demand.
Wyatt opted for a Bosch MS25 Standalone ECU, custom-tuned by experts Mark Broviak and Jeff Hale from Exergy. Additional electronic components, including a PCS2800, two PMU16s for power distribution, an AEM dash, and a 22-channel module, ensure precise control and monitoring of the Duramax engine’s capabilities.
Routing the exhaust with finesse, Wyatt employed 5-inch PPE and in-house crossover-to-turbo straight-pipe exhaust manifolds finished in polished titanium. This not only contributes to performance, but also adds a touch of visual flair to the drag race-ready K15.
Wyatt Stengel’s 1970 GMC K15 stands as a testament to the relentless pursuit of diesel performance in the Duramax world.
Diesel of the Week is sponsored by AMSOIL. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor Greg Jones at [email protected].
