It’s Time For A 6.6 Liter Duramax Dyno Day


Hang on to your hats, it’s time to present the second installment of our “brand-specific” Diesel Army dyno series. We originally started with a high mileage 7.3-liter Power Stroke dyno day and now we move onto the mighty 6.6 liter Duramax. The Duramax is one of those engines that came onto the scene rather quietly in 2001, but over the years has just become an all-out powerhouse. Prior to 2001, the GM diesel offerings were dated, to say the least.

When GM and Isuzu partnered up to design the Duramax, they were definitely onto the makings of something special. It is the only engine currently produced in this segment that hasn’t been completely redesigned, has not needed to increase displacement to meet emissions, and has been one of the quietest engines for more than a decade now.

Behind the 6.6 Liter Duramax

  • Bore: 4.06 in
  • Stroke: 3.90 in
  • Displacement: 403 Cubic Inches (6.6L)
  • Injection: Direct Injection Common Rail
  • Turbo: Single Turbocharger

LB7 (2001-2004)

  • Base Horsepower: 235 hp at 2,700 rpm
  • Base Torque: 500 lb-ft at 1,600 rpm

LLY (2004-2006)

  • Base Horsepower: 310 hp at 3,000 rpm
  • Base Torque: 520 lb-ft at 1,600 rpm

LBZ (2006-2007)

  • Base Horsepower: 360 hp at 3,200 rpm
  • Base Torque: 620 lb-ft at 1,600 rpm

LMM (2007-2010)

  • Base Horsepower: 365 hp at 3,100 rpm
  • Base Torque: 660 lb-ft at 1,800 rpm

LML (2011-present)

  • Base Horsepower: 397 hp at 3,000 rpm
  • Base Torque: 765 lb-ft at 1,600 rpm
As GM has made refinements to the Duramax over the past decade, the identification number has changed. When they initially launched, the Duramax option was called an LB7, which was produced from 2001 to 2004. This new engine featured an aluminum cylinder head with four valves per cylinder, a single non-vgt turbo, and a common rail injection system.

Mid-2004, there were some updates put into place and the new version was called an LLY. The biggest of these new updates was the introduction of a variable geometry turbocharger, and injection rail pressure not able to go up to 23,000 psi. The LLY was produced until early 2006.

A new powerhouse was introduced called the LBZ in 2006. This two-year engine (ended in 2007) received a lower compression ratio, upgraded injectors, and a faster and more robust ECM.

As the emissions requirements tightened, additional changes were needed and the new version was called the LMM (2007 to 2010). The LMM has the distinct honor of being GM’s first Duramax with a Diesel Particulate Filter (DPF) as well as a Diesel Oxidation Catalyst (DOC). Even with these power-robbing devices, the Duramax was still able to squeeze a little more power out of the engine than the previous LBZ.

Finally, the last major emissions regulations went into full effect and the LML was introduced (to present). Once again the compression was dropped, but even more power was squeezed out of the engine. (Click here for a more detailed history of this engine.)

For this dyno day, we wanted to get a good mix of what is actually running around on the streets. So, we invited guys with all different levels of modifications out to roll the dyno.

Curtiss Johnson’s 2007 Chevy

First up on the rollers was Curtiss Johnson in his 2007 Chevrolet Silverado 2500 HD.

Johnson is an excellent example of how incredible the 6.6 liter Duramax can be with very few modifications. Knowing the Allison transmission goes into limp mode as the horsepower starts to go up, we took the truck over to Inglewood Transmission and had them work their magic.

Johnson’s 2007 LBZ 6.6 Liter Duramax

  • Turbo: Stock
  • Tuner: EFILive
  • Injectors: Stock
  • Best Run: 522.4 hp, 932.3 lb-ft of torque
Once he didn’t have to worry about limp mode, he swapped the factory exhaust for a 4-inch MBRP exhaust. Then he added Boost, EGT and Fuel Rail Pressure gauges, plus had an old friend tune his truck using EFILive.

With the truck performing how he wanted, he focused on the suspension. The guys at J&S Motorsports went through everything to get the truck not only reliable, but heading straight down the road. They upgraded his shocks to Rancho 9000 series, added Hellwig Products anti-sway bars in the front and rear, Cognito Motorsports A-arms, DMAX Kryptonite series tie rods, center link, and a set of Calvert Racing CalTrac traction bars. “The Hellwig bars really smoothed out my boosted launches,” said Johnson.


To add some styling to the truck, he added some 17-inch American Racing Teflon Coated ATX series wheels wrapped in Nitto Dura Grapplers.

So, that’s great, but how did it do? Well, he was able to lay down 522.4 horsepower and 932.3 lb-ft of torque. That is a pretty stout number for a 125,000-mile daily driver that occasionally hits the track. Johnson is a perfect example of the right modifications on these trucks can yield fantastic results.


Doug Barnes’ 2005 GMC

Barnes got bit with the performance bug thanks to his friend’s 7.3 liter Ford Excursion. One ride and Barnes knew his truck needed more power! Under the hood of his truck is a SoCal Diesel long-block that has been bored .020-inch over and assembled by friend and master technician, Robert Miller. The long block features Carrillo connecting rods, SoCal Diesel’s 3388 Hot Street/Tow camshaft, their Stage 1 ported heads, ARP main and head studs, and ATI harmonic damper.

Barnes’ 2005 LLY

  • Turbo: Garrett GT4094VA
  • Tuner: EFILive tuning by Ridge Runner Diesel Performance
  • Injectors: 60% over Exergy
  • Best Run: 677.5 hp, 1032.9 lb-ft of torque
For fuel, Barnes is running Exergy Performance 60-percent over injectors fed by a dual CP3 kit from Motorsport Diesel that is supplied by an AirDog 150 gph lift pump. To support that much fuel, an S&B cold air intake lets air in and it is routed to the turbo via an aFe POWER Bladerunner turbo manifold. The turbo is a Garrett GT4094VA with a billet compressor wheel that Danville Performance put together. The boosted air is sent through a Banks Power Technicooler intercooler and then into a custom Y-Bridge that Jason Wherli made for Barnes. On the exhaust side, the manifolds were swapped out in favor of PROFab Performance log style headers and up-pipes. The downpipe is a 3-inch Diamond Eye that connects to their 4-inch exhaust kit.

Behind the engine is a Stage IV transmission from Inglewood Transmission. For tuning, Barnes is running an EFILive tuner with custom tuning done by Ridge Runner Diesel Performance. All that power is transferred to the axles and then to the 18-inch Mickey Thompson Classic Lock Wheels wrapped in MT Baja ATZ 325/65-R18 tires. The truck also features a 6-inch Fabtech lift.

So how does the white stallion handle the rollers? The truck handled the rollers extremely well; the two runs that Barnes through down were almost spot on with each other. His truck laid down 677.5 horsepower and 1,032.9 lb-ft of torque. As with almost all of the guys at the event, Barnes uses the truck daily and for long road trips. So, just because it is lifted, doesn’t mean it doesn’t have what it takes to leave someone in the dust!



Sean Lindenberger’s 2006 6.6 Liter Duramax

Right in the middle of our group of five was Sean Lindenberger’s ’06 GMC Sierra 2500 HD.

The “Cocaine Cowgirl,” as Lindenberger likes to call her wasn’t one to disappoint. There’s more going on under the hood than most people would think. The engine has been fully built by PPE and features Carrillo rods, Mahle Motorsports pistons, SoCal Diesel camshaft, and heads. For airflow, an aFe air filter directs clean fresh air into a custom set of compounds. A BorgWarner 66 mm S300 high-pressure turbo is paired with a BorgWarner S400 with an 80 mm compressor wheel. Both turbochargers feature race covers to help add that little extra flow.

To cool the air back down after being compressed, a PPE intercooler was installed. Once the air is in the cylinders, it is compressed and met by fuel being injected from the Exergy Performance 100-percent over injectors that are fed by a dual CP3 setup by PPE. The engine is paired with an Inglewood transmission and together they are tuned by an EFILive tune that was custom written for Lindenberger by SS Diesel tuning.

Lindenberger’s 2006 LLY

  • Turbo: 66mm S300 high pressure and 80mm S400 low pressure
  • Tuner: EFILive tuning by SS Diesel
  • Injectors: 100% over Exergy Performance
  • Best Run: 889.4 hp, 1307.1 lb-ft of torque
Outside, the truck sports an 8-inch Pro Comp lift to clear the Cooper Tires 305/50R-20 Zeon LTZ paired with Method Racing Wheels. To give the truck a pre-runner look, a custom front bumper was made and paired with a Rigid Industries light bar. To complete the look, Lindenberger painted the roof black and added a custom hood.

Lindenberger is a fun guy and we thought he was joking when he said he wanted his 6.6 liter Duramax to make 1,000 horsepower. Little did we know that he was serious. We strapped the Cocaine Cowgirl down and let her rip. She ended up laying down 889.4 horsepower and 1,307.1 lb-ft of torque. On top of that, Lindenberger has a nitrous bottle mounted in the bed, it just wasn’t plumbed. So, we can certainly see 1,000 ponies coming from this cowgirl shortly!

6.6 liter Duramax


Brian Howard’s 2006 Chevy

With a huge run of Lindenberger, we started having high hopes for the remaining trucks. By our numbers, the two remaining trucks should on paper be able to lay down more than Lindenberger. Brian Howard’s 2006 HD usually runs about 10 seconds faster in the eighth-mile (7.40s) than Lindenberger does. One of the beautiful things about Howard’s truck is that he not only uses it daily, but he regularly hauls his fifth wheel with his truck. This is truly a “have your cake and eat it too” type of rig.

Howard’s 2006 LBZ

  • Turbo: Garrett 4094VA high pressure and S483mm low pressure
  • Tuner: EFILive
  • Injectors: 70 percent over Exergy Performance
  • Best Run: 774.6 hp, 1176.6 lb-ft of torque
How does he accomplish that? Well, for starters, he is running EFILive tuning with a five-position switch. So, he usually has the truck turned down to mid 600 horsepower for the street, and mid 400s for towing. For performance goodies under the hood, it all starts with a SoCal Diesel Stage 2 engine. That means he is running a factory crank, Carrillo forged rods, Mahle Motorsports pistons, ARP head and main studs, SoCal Stage 2 cylinder heads with chromoly pushrods, billet flex plate and a SoCal Diesel custom camshaft.

On top of that, Howard is running PPE’s Dual Fuelers that feed Exergy Performance 70 percent over injectors. The exhaust flows out the heads and is directed into the turbos thanks to ProFab Performance’s exhaust manifolds and PPE’s up-pipes. The high-pressure turbo is a Garrett 4094VA which is fed by a Bullseye Power S483. All of the air is then directed through a PPE intercooler and into the engine.

The power is directed to the rear via a fully built transmission by Inglewood transmission. Howard did opt for a relatively high stall converter from Suncoast (2,400 rpm). In the back, there is an Eaton Truetrac locker. Howard is also running Calvert Racing CalTracs traction bars and a set of Firestone airbags in the rear.

To keep the truck stable and riding nicely, there are QA1 shocks on all four corners. For wheels and tires, Howard opted for a set of American Racing ATX series wheels that are coated with Teflon. They are wrapped with Nitto 285/75R-17 Dura Grapplers. These give him all of the grip he needs for the track and have a good life.

So, when we strapped down the 6.6 liter Duramax LBZ, we had high hopes. Howard was playing it tight-lipped, but didn’t expect it to lay down more than Lindenberger’s 889. During each of the pulls, the truck was producing 40 pounds of boost (about 20 psi lower than he sees on the track) and put down 774.6 horsepower and 1,176.6 lb-ft of torque. This was with 100-percent load from the dyno. Being 20 psi down from max does indicate that there should be more left in the truck, but today, she just didn’t want to give it to us.

6.6 liter Duramax


Ruben Angeles’ 2009 6.6 Liter Duramax

Next up, was the truck we all were keeping an eye on. Ruben Angeles’ 2009 GMC Sierra 2500. This LMM has gone through a wide range of configurations over the years and Angeles really knows his stuff. Regularly running low 7s in the eighth-mile, this truck should be a high 10-second street-legal truck.

To achieve that, the rods were swapped out in favor of Carrillos, and the pistons were upgraded to a set from Mahle Motorsports. The rest of the engine is actually still stock (heads, cam, crank, etc). For fuel, Angeles opted for a large (250% over) set of Exergy Performance injectors that are fed by PPE’s dual fueler kit. While that much fuel isn’t easy to clean up, the custom compounds built by WTB Muffler (Wholesale Tube Benders) do a decent job of it.

Angeles’ 2009 LMM 6.6 Duramax

  • Turbo: S475 high pressure and 98mm S400 low pressure
  • Tuner: EFILive tuning by Power Performance Enterprises
  • Injectors: 250% over Exergy Performance
  • Best Run: 861.9 hp, 1262.8 lb-ft of torque
The high-pressure charger is a Bullseye Power 75 mm and it is fed by a Gillet Diesel PBK (Phat Bastard Killer) 98 mm low-pressure charger. The truck has custom EFILive tuning by Kory Willis at Power Performance Enterprises (PPEI). The transmission is built by Inglewood Transmissions, and Angeles is using a 2,800 rpm stall torque converter

To give the truck its stance, Angeles went with a DJM 3-inch front lowering kit and pulled all but two leaves from the rear. To keep the axle pointed forward and not up at the sky, he opted for a set of Calvert Racing CalTracs traction bars. Moving the 7,200-pound beast is done via a set of 20-inch American Eagle Wheel Series 14 wheels wrapped in 285/50R-20 Nitto NT420 tires.

So, with much anticipation, we strapped her down. As all watched, we made pull after pull trying to find the sweet spot to lay down the good numbers. Shortly after making a few pulls, we started seeing rubber behind the dyno, indicating that the tires were spinning. So we aired down the tires, added as much weight as we could find laying around in the shop (a few hundred pounds), and made a few more pulls. The best number the 6.6 liter Duramax managed to get was 861.9 horsepower and 1262.8 ft-lbs of torque. As good of a dyno number as this is, it is actually short of what the truck is able to put down. We were still 30 psi short of maxing out the system (90 psi max) and the tires were still slipping on the dyno. This truck is a beast and it is a little sad that today wasn’t its day to show itself.

6.6 liter Duramax

All said and done, it was a great time for everyone and we managed to put down over 3,700 horsepower and over 5,700 lb-ft of torque with five 6.6 liter Duramax trucks. That is a pretty good day and shows that there are some very impressive Duramax trucks in the Southern California area.

Top Torque numbers of the day:

  1. Sean Lindenberger ’06 GMC 2500 1,307 ft-lbs
  2. Ruben Angeles ’09 GMC 2500 1,262.8 ft-lb
  3. Brian Howard ’06 Chevy 2500 1,176.6 ft-lbs
  4. Doug Barnes ’05 GMC 2500 1,032.9 ft-lbs
  5. Curtiss Johnson ’07 Chevy 2500 932.3 ft-lbs

This is only the second dyno day in a long series of Diesel Army dyno days that we have planned out. So, stay tuned and keep an eye out on our Facebook page for more announcements to come. Who knows, it may just be your truck that we get to strap down next!

About the author

Chad Westfall

With diesel running through his veins from childhood, Chad has more than a decade of experience in the automotive industry. From editorial work to wrenching, there isn’t much he hasn't conquered head-on. When he’s not writing and shooting trucks and tech, you’ll find him in the shop working on turning the ideas floating around in his head into reality.
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