Inside DmaxStore’s 6.6L Diesel Wake Boat

MasterCraft X-80 Boat Build

Here at Diesel World, we’ve seen our fair share of swaps and wild custom builds, but every so often something rolls in that forces us to stop and rethink what’s possible. This boat checks every box. Meet the MasterCraft X-80—but it’s not the one you think you know. This particular X-80 ditched its gas-fed roots and now roars across the water with the heart of a 6.6L Duramax diesel thanks to the crew at DmaxStore.

On paper, dropping an LMM Duramax into a wake boat sounds like the kind of project you dream up late at night but never actually follow through on. But DmaxStore made it happen, and the result is more than just a proof of concept; it’s a statement about what diesel power can do outside its usual lane.

Like any great build, it started with a vision. The idea was simple but bold—push the boundaries of what a diesel swap could look like by stepping into the marine world. That meant tackling challenges no truck build has to face: tight engine bay constraints, cooling concerns, propeller matching, and a transmission setup that could handle big torque in water instead of on pavement.

The first major hurdle came quickly. Duramax engines aren’t exactly small, and the stock oil pan made fitment inside the X-80’s engine bay nearly impossible. The solution came in the form of custom fabrication, with a modified pan and pickup that let the LMM sit exactly where it needed to. From there, the snowball rolled. Custom stainless manifolds were designed for liquid cooling, a freshwater impeller adapter was built from scratch, and a ZF V-Drive transmission was paired with a billet flexplate adapter to connect diesel torque to the marine prop. A custom exhaust system, wired electronics with a PPE harness, ARP head studs, a full closed-loop cooling setup with a heat exchanger, and a Peninsular Diesel oil cooler round out the major systems. In other words, nothing about this project was plug-and-play.

The fuel and air systems had to be reimagined too. An AirDog II 165 lift pump, modified OE pickup, and water-to-water intercooler kept the Duramax fed and cool, while a Garrett Stage 1 turbo pushed fresh air into the mix. The end result was roughly 450 horsepower, planted firmly in a hull that was never designed for this kind of grunt.

Performance on the water was everything the team hoped for. The boat consistently ran around 40 mph during testing and has potential for more as prop configurations evolve. More impressive than top speed, though, was the way the boat handled loaded surf sessions, with steady temps, safe EGTs, and plenty of boost to haul passengers and ballast without breaking a sweat.

Of course, a build like this is about more than the drivetrain. The X-80 received a full refresh inside, with custom marine upholstery from Gabe’s, a triple-layer GatorStep deck featuring DmaxStore logos, ambient RGB lighting, and a JL Audio system that makes sure the sound above water matches the thunder below. It’s as polished as it is powerful.

Community played a role in this build too. The DmaxStore team leaned on feedback from MasterCraft forums and prop experts to dial in the setup. Advice on cooling strategies, vibration management, and prop pitch fine-tuning all helped refine what was already a wild idea into a functional boat. In true enthusiast fashion, it was as much a community project as it was a shop job.

At the end of the day, this isn’t just about one boat. It’s about proving that diesel has a place anywhere power and durability matter—even on the water. The DmaxStore MasterCraft X-80 is a conversation starter, a head-turner at the dock, and a blueprint for what’s possible when you stop asking “why?” and start asking “why not?”

For DmaxStore, it’s another chapter in the brand’s story defined by pushing boundaries, taking risks, and showing what can be done when you refuse to settle for ordinary. Trucks may be its bread and butter, but with a Duramax-swapped wake boat now in the fleet, DmaxStore has shown that its creativity doesn’t stop at the shoreline.

PHOTOS BY DMAXSTORE