Compound Turbo 12-Valve Cummins Engine - Engine Builder Magazine

Compound Turbo 12-Valve Cummins Engine

Beginning this diesel build with a core Cummins engine that looked like it had been at the bottom of the ocean, Dakota Sargent of Fullhook Performance was tasked with turning the 12v Cummins into a SEMA-level engine build. See what he was able to deliver!

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Dakota Sargent is one of our favorite up-and-coming engine builders for a multitude of reasons. Still in his 20s, he’s cultivated a remarkable diesel engine building business that’s pumped out several really cool Cummins builds over its three-year lifespan, thus far. Even more impressive is the fact that Dakota runs Fullhook Performance as a two-man operation with his sole employee Connor Bonham.

The shop is based in Indian Springs, NV, a small town just 30 minutes outside of Las Vegas. Its still relatively small, but it’s highly respected in the industry, with a strong presence on social media. Dakota has been steadily building a reputation for his work, amassing an impressive 10,000 followers on Instagram.

This is his third time in our Diesel of the Week series, and we implore you to check out his 12v and 24v engines we’ve already featured. The duo recently finished another 12v Cummins engine that is sure to turn heads.

This particular 12v will be going into an OBS dually truck that OBS Headquarters is building for next year’s SEMA show (2024).

“We fully build our engines from the ground up, and this one was probably one of the worst core engines I’ve ever been given,” Sargent told us. “It looked like it came from the bottom of the ocean when I got it, so it’s really come a long way.”

Sargent still uses Head by Rick (HBR Competitions Engines) as his go-to machine shop until he can do his own work. For this particular build, HBR balanced the rotating assembly, resized the rods, balanced the crank, line-honed the main journals, decked and o-ringed the head, and bored the block .020″ over using torque plates.

The engine features a plethora of high-performance components, each carefully chosen to deliver exceptional power and reliability. Dakota rattled off each of the engine’s components from memory, demonstrating an impressive knowledge of his craft. The build includes a wide range of upgrades, from valvetrain components to fuel and air systems:


  • Manton 7/16-inch pushrods
  • Manton conical valve springs and retainers
  • Hamilton 178/208 cam
  • ARP 625 head studs
  • ARP 2000 main studs
  • ARP rod bolts
  • Mahle H-series bearings


  • Farrell-built Stage-3 180 pump with 450cc flow
  • Stage-3 DDP 12v injectors
  • Fullhook -6an AM return line kit w/ Tork Tek overflow valve


  • Evil Fab compound kit
  • 63/68/14 T4 manifold charger
  • S475 96/132 T6 atmospheric charger
  • Steed Speed T4 manifold
  • Fleece Performance stainless manifold studs
  • Turbo feed lines and drains built in-house

Additional Features:

  • Fullhook billet intake plate and freeze plugs
  • Keating Machine front cover and billet valve cover
  • Diesel Conversion Specialist billet adapter plate
  • Big Iron oil pan
  • Fleece coolant bypass with custom mounts

It’s also worth noting that Dakota aims to create engine dress-up parts with his own branding to set his engine builds apart from the rest. He’s determined to ensure that the recognition for his engine builds extends beyond performance and reliability and includes the aesthetic appeal.

“This one makes around 700 horsepower, and it’s kind of our street series build we do for customers who want a decent amount of power.” All we can say is this Cummins came a long way from how it looked as a core engine to now a SEMA-level engine build.

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].

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