Triple-Turbo 6.6L LLY Duramax Engine - Engine Builder Magazine

Triple-Turbo 6.6L LLY Duramax Engine

The LLY Duramax often catches some flak for having overheating issues, but that doesn't stop some people from using it in their one-off diesel builds. Thomas even went as far as putting triple-turbos on his engine!

Diesel of the Week is presented by

“This truck is pretty much what got me into the diesel side of things,” says Thomas, a welder turned diesel enthusiast. “I just started cruising the forums, watching a lot of the videos and how-to’s and asking questions.”

Tom’s journey didn’t start with a background as a mechanic or an automotive engineer like some. He was a welder and would take on various jobs, from fabrication to repairs. Tom’s passion for diesel work began when he acquired his 2006 Chevrolet Colorado. Ever since, he’s been completing all the work on the truck himself in his garage.

“I bought this truck in 2014, when I moved to my permanent-duty station in the Marine Corps,” Tom says. “It kind of started off as a joke, just wanting to do a 4WD truck and drop this engine into, but then it actually started coming together and becoming more and more.”

Tom’s friends at the time doubted the feasibility of what he had in mind – dropping a diesel into the frame of an ’06 Colorado was a tall order, but ultimately, he was successful in his endeavor.

The heart of Tom’s project is a 6.6L LLY Duramax engine. He explained that he chose the LLY engine because it had the largest factory turbo, which allowed him room for other significant upgrades early on.

Some of the key modifications he highlights include 60% over injectors, PPE down pipes, up pipes, manifolds, and their dry sump system. Tom runs a 66mm RDS turbo currently.

What sets his build apart is the introduction of two Comp Turbo S366 turbos mounted in the valley. They aren’t tuned and turned on yet, but once ready, he plans to pair it with a stroked CP3 pump and hopefully make close to 1,000 horsepower. Currently, with the single turbo, he estimates it to be around 600 horsepower.

“Right now, I’m just getting the piping all fabricated in and that’s proving to be a challenge,” he admits. “I have the intake side pretty much done, then I got to do the intercooler side and the exhaust.”

He’s not only taken on the mechanical challenges of building a one-of-a-kind truck, but also the fabrication and welding that’s required for such a unique project.

In addition to the engine, Tom’s truck features a four-link suspension, a Dana 60 front axle and 14-bolt rear axles, and 4.88 gears. The exhaust system is nothing short of extraordinary, featuring six diamond stacks fabricated by Tom himself.

While Tom’s truck is currently focused on the show scene, he has plans to put it to the test in off-road environments after working out any bugs in the setup. His dedication and passion for diesel performance have not only resulted in an impressive build, but have also inspired others to take on similar projects.

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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