Twin-Turbo LB7 Duramax Engine - Engine Builder Magazine
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Diesel of the Week

Twin-Turbo LB7 Duramax Engine

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What is there to say about Lavon Miller that hasn’t already been said? He’s the owner of the uber-popular Firepunk Diesel and has a laundry list of commendations and awards in diesel motorsports. Most notably, Miller was a three-time consecutive Ultimate Callout Challenge victor and led the Firepunk team to making history with the first-ever diesel 3-second pass in the eighth mile.

Even outside of all the accomplishments, we hear Lavon’s name just about everywhere. Mostly, it’s Diesel of the Week guys who got their trucks tuned by him or a transmission from Firepunk. Justin Ziegler’s record-setting 6.7L Cummins engine was tuned by Miller. Ziegler told us that “Lavon is simply doing Lavon on the laptop” – and that means a lot when the result is a 3,336-horsepower dyno pull and a 4.99-second 1/8th-mile pass.

Point being, it’s always a treat to check up on Lavon and see what he has cooking up over at Firepunk Diesel. The shop does everything from basic mods to the extreme, and that means transmissions, compound turbo kits, engine conversions, complete builds and the like. Luckily, Miller drags a lot of these builds out to trade shows and competition events for us to take a closer look at.

At the Ultimate Callout Challenge this year, we were taken aback by one of his builds, a stunning Z28 Camaro he modded for a customer out in Texas. The muscle car itself was built by the owner years ago alongside his son, who drove it to his high school graduation. Once college came, he lost interest in it and it got sent back to the owner’s garage to sit. After some time passed, he was eventually bitten by the diesel bug.

Miller was asked to build something capable of around 1,200-horsepower that could be driven both to get ice cream on a Sunday afternoon and taken to the drag strip for a 9-second pass on a Friday night. The result is a Camaro with an LB7 Duramax fit snuggly under the factory hood, which surprisingly, doesn’t look out of place. In fact, the hefty engine fits the mold just fine.

The motor itself is Wagler’s Streetfighter Duramax platform, that comes assembled with a Callies billet crank, MAHLE pistons, narrowed Wagler rods to fit the crank, Wagler heads, and Trend rocker arms and pushrods. Miller says with all the supporting mods, it could make up to 1,500-horsepower if needed.

Adding to the cool factor of the diesel swap is a twin-turbocharger system, something rare for diesel engines, which more commonly see a compound turbo setup rather than true twins.

“It really just started as doing twin-turbos for the cool factor, and then the concern was if we could actually get the drivability out of it,” Miller says. “We did some studying and math with the rpm and found something that works. These are 58mm GT30-based turbochargers and the intercooler is fed on each side, so both banks will share the same boost pressure. The car isn’t running yet, but mathematically on paper, it should drive pretty decent.”

On the fuel side of things, Miller relies on Exergy 150% over injectors, a 12mm stroker CP3 fuel pump, and a Bosch MS25 ECU to control the air-fuel ratio. The Bosch ECU allows for much more control of the build, according to Miller, where the injectors and pumps are calibrated perfectly to a smoke map. The driver is able to utilize 100% throttle and the ECU will handle the smoke control.

Miller also fitted the Camaro with a Rossler 4L80E transmission and other amenities like a radio and retrofitted air conditioning system that allow it to retain its comfortability on the street.

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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