Compound Turbo 6.6L LB7 Duramax Engine - Engine Builder Magazine

Compound Turbo 6.6L LB7 Duramax Engine

After building a compound turbo LB7 Duramax to the tune of more than 1,200 HP, Dark Horse Diesel owner Mike Maas was hungry for more. He decided to build up another LB7 Duramax with an LML block and is now seeing the potential to hit 2,000 HP. Find out how he's getting there!

Diesel of the Week is presented by

Mike Maas is a jack of all trades kind of guy. Like most people in the automotive repair and performance industry, he got his start fixing up his friends’ rides. That slowly, but surely, led to him growing a customer base in his community that he eventually leveraged into a business.

Five years ago, Maas started up Dark Horse Diesel LLC in the small town of Watkins, MN. With a population of only 935 people in Watkins, Dark Horse Diesel’s one-man-operation is the perfect size to get the job done and provide for all diesel needs in the area.

2003 Chevy Silverado

Maas has a single hoist in his 28’x60’ shop and mainly focuses on repair, performance and tuning work on Chevrolet and Dodge trucks. Dark Horse Diesel also specializes in Duramax engines and Allison transmission work.

For machining work, Maas goes to Craig Brutger of Craig’s Machine and Dyno, who he says is the best in the state of Minnesota. For this Diesel of the Week, we’re featuring Maas’ 2003 Chevy Silverado that he decked out with a fully built 6.6L Duramax LB7 engine.

LB7 Duramax

“It was just a typical shop truck when I got it,” Maas says. “It was a toy we ran around in and messed around with from time to time. It kept progressing overtime and went through a lot of changes before it got to where it is now.”

To his word, Maas still uses the truck for just about everything as his daily driver. He decided on a regular cab truck amid a sea of three and four-door trucks because of his love for the LB7. In fact, he’s owned seven LB7 trucks over the years, all of which he’s been impressed by.

This Silverado went through a gradual evolution over the years, from a mild shop truck to a souped-up powerhouse. The earlier build consisted of a stock LB7 bore block with a balanced stock crank, Carrillo connecting rods, MAHLE Motorsports cast de-bowled pistons with valve reliefs and 16.1:1 compression ratio.

For the camshaft, Maas enlisted the help of Craig’s Machine and Dyno to make a custom firing order camshaft that moves the valves in a pair of Wagler Competition street cylinder heads. The engine also featured a compound turbo setup consisting of a BorgWarner S485 atmospheric turbo and a BorgWarner S369SXE valley-mounted turbo, which was tied together by HSP Diesel.

These parts, along with some other custom additions and EFI tuning by Danville Performance, brought this early build to a peak of 1,244 hp and 2,193 lb.-ft. of torque. Maas took the truck down to Scheid Diesel for the dyno competition and ended up winning two years in a row.

In the time since this build was finished in 2017, Maas has made some notable changes to add 300+ horsepower to the Duramax.

“We dyno’d the thing to over 1,500 hp, but didn’t really go farther than that,” Maas says. “There was a good amount of fuel left and if I had to guess, I think it could have hit 2,000 hp if we kept going.”

The new motor that Maas refreshed and built this year is another LB7 in terms of the heads, injectors, etc., but this time he opted to use an LML block.

The engine has a Callies Ultra billet crankshaft and CP forged pistons. A Callies hybrid kit was also installed. The bottom of the engine is all billet, with a billet SoCal stud girdle, SoCal mains, and an ATS flywheel. Up top, the Duramax now features a set of Kill Devil Diesel cylinder heads.

Maas also opted to change the compound turbo setup for some added power. HSP Diesel handled the turbo setup again, installing a BorgWarner S476 in the valley with a 12mm S&S pump and a Garret 102mm GT55 on top with a 10mm S&S pump on the belt. S&S 300% over injectors provide the fuel and round out this awesome setup.

“It’s all just really reliable,” Maas says. “I haven’t really had any problems with it yet and I hope it stays that way.”

While Maas’ Silverado may look like an unassuming shop truck on the outside, it’s sure to make onlookers double-take as it flies down the drag strip.

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].

You May Also Like

Turbocharged 6.7L Second Gen Cummins Engine

Thanks to attending a truck pull event at an early age, Sean Purdy can’t shake his passion for diesel trucks and engines. He recently completed a fresh build on his 1999 Ram 2500 with a turbocharged 6.7L Cummins second gen-swapped engine.

6.7L Cummins engine

Engines are inherently cool. That’s not new news to Sean Purdy. He’s been into anything with an engine since he was about 3 years old. From there, it didn’t take long to get into diesels. His diesel passion began with diesel lawn tractors and escalated into diesel trucks after attending his first truck pull.

Turbocharged 5.9L Cummins Engine

As an industrial millwright, Devan Leeds has a lot of knowledge and skills with his hands. He’s also a thrill seeker when it comes to high-speed vehicles. Case in point, his ’03 Ram 2500, which features a rowdy, turbocharged 5.9L Cummins engine under the hood. Check it out!

Leeds Fabrication 5.9L Cummins
Compound-Turbo 6.0L Powerstroke Engine

Steve Burton of New Performance Automotive and Chris Moore of Flatwoods Diesel Performance recently teamed up to build this compound-turbo 6.0L Powerstroke engine. Check it out!

Compound Turbo VP44 5.9L Cummins Engine

Cole Sojka’s diesel truck journey began at the age of 16 when he bought a 2001 Dodge Ram 2500 as a farm truck. Over the past eight years and 100,000 additional miles, he’s transformed the truck, including building up the 5.9L VP44 compound-turbo Cummins engine. Check out the build!

Cummins engine
Single-Turbo 5.9L Cummins Engine

Aaron West has done a few smaller scale builds to date, but he recently finished up a “Frankenstein” truck that is pretty impressive. The body is a 1990 Dodge D150, while the chassis is from a shortened 2003 Dodge 2500 4WD, and the engine is a turbocharged 5.9L Cummins. It’s our Diesel of the Week!

Dodge truck and 5.9L Cummins engine

Other Posts

AMSOIL Signature Series 0W-16 100% Synthetic Motor Oil 

AMSOIL Signature Series 0W-16 100% Synthetic Motor Oil provides next-level engine protection primarily for those with Toyota and Honda applications calling for a 0W-16 viscosity.

Twin-TorqStorm-Supercharged 454 cid Big Block Chevy Engine

It had been more than two decades since Val Morris of Steve Morris Engines was behind the wheel of a drag car. This Chevy Malibu with a twin-supercharged 454 big block Chevy engine was her forray into drag-and-drive, and now she wants to go even faster!

Scheid Diesel-Built Triple-Turbo Billet 6.4L Cummins Super Stock Engine

During our visit to Scheid Diesel we had our mouths wide open in amazement for most of the time, but this Super Stock pulling engine really made our jaws drop! Scheid’s Joe Gasper walked us through the details of this billet triple-turbo 6.4L Cummins build, and it’s our latest Diesel of the Week brought to

Steve Morris Engines’ Twin-Supercharged 454 Big Block Chevy Engine

It had been 26 years since the last time Val Morris, Steve Morris’ wife, was behind the wheel of a drag car. The shop had been working on this project car named Sugar Momma, and got it done in time for Sick Week 2024. When it came time to figure out who’d drive it, Steve