Diesel Tuner's Blog

With so many drop-in turbo upgrades to choose from it can be hard to make sure you're getting exactly what you want, and need, out of a drop-in turbo upgrade for your '04.5-'16 Duramax. Could your stock LLY, LBZ, LMM, or LML turbo be enough to crank out the power you're looking for if you really turned it up?  Do aftermarket replacements really live up to their claims? Today we'll take an in-depth look at what you can expect out of varying levels of drop-in turbo upgrades for your 6.6L Duramax and compare them to what the your stock charger can provide. Below is the data from our in-depth engine dyno testing of a Stock VVT/LML turbo, Stealth STR, Stealth Mach 1, and Stealth Mach 2 turbo. All tests were conducted on a built LBZ engine connected to our Dyno-mite water brake engine dyno.  This empirical data was gathered under real-world circumstances, with a serious effort made to control as many variables as possible for consistency. Installation, instrumentation, and operation of this engine through a gauntlet of tests that took several weeks.

Turbo and Test Descriptions

Dyno Engine: The platform that we will be using for this test is a 2007 6.6L LBZ Duramax that received the following upgrades before testing:

• Custom tuning
• S&B Cold Air Intake
• 100% over injectors
• 10mm CP3 pump
• Head studs
• Alternate firing order cam
• Upgraded pistons
• Upgraded crank shaft
• Upgraded connecting rods

These upgrades were necessary to be able to handle the power levels that we pushed this engine to during the testing of all 4 of these turbos. 

Testing: We performed three tests to gauge the overall performance of each turbo in comparison to each other. Obviously the bigger the turbo, the more top end power. But what about all the other factors that go into creating that power like drive pressure, EGTs, air/fuel ratio, etc? What about in towing conditions and all-around drive-ability? The first test that we will present is the "Max Power" test which is your traditional dyno and power test.  This test will provide a general comparison in terms of the difference in power that these different turbo options can produce. The second test presents spool up data and will give a good visualization of the difference in drivability and turbo lag that each turbo can provide. Finally our "Tow Test" is the ultimate data provider, providing insights on key data points including EGT's, drive pressure, air/fuel ratio Ect...

One of the biggest advancements in turbo design since we first started applying them to diesel engines over 70 years ago has been the invention of Variable Geometry Turbos. These turbos utilize a set of movable vanes on the inside of the exhaust housing that allows the actuator to vary the area in which exhaust gasses can pass through them. This allows the exhaust side of the turbo to increase or restrict the flow of exhaust hitting the turbine wheel. In some designs it also changes the flow direction of gasses hitting the exhaust turbine as you can see illustrated below. 


When restricted, the velocity of the exhaust gasses increases which helps spin the turbine faster than a fixed geometry turbo would. This gives the turbo the ability to spool the turbine and compressor wheel up much better than it normally would even with a low volume of exhaust pressure traveling through the system. This helps to spool the turbo at lower RPMs to create boost where it would normally be lacking. This is why variable geometry turbos (VGTs) are such an advancement. They have the ability to significantly reduce turbo lag and provide much better response and turbo efficiency across a range of RPMs. 

New Product Release: L5P Stealth STR Turbo
Calibrated Power was the very first custom tuner to tune the L5P Duramax platform and have been building custom turbos and tuning for over 15 years. We know exactly what these trucks respond to and need to get the best performance out of them. Now with their newest addition to the L5P performance market, the L5P Stealth STR. We've used what they have learned about the L5P platform to provide a drop-in stock turbo replacement that offers improved performance and reliability at a similar price to a stock turbo replacement. 

Here are the features: 

• Airflow that Supports 625hp with stock emissions in-tact
• Brand New parts and electronics
• Custom 7-blade extended tip billet compressor wheel
• Designed and spec'd with the help of tuning experts at DuramaxTuner

We all ask the question at some point, should I upgrade my turbocharger?  Improving performance is always something us diesel owners are thinking about.  Maybe your charger blew up or maybe you just want to help cool your truck's EGTs a bit more.  There are a ton of different reasons why you may want to upgrade.  With that comes a ton of different variables that go into which turbo you SHOULD buy.  Let's take a look at three big areas to consider. 

#1: How Do You Use Your Truck?

You've probably heard this one before, if you're new to the diesel world maybe you haven't.  Either way its a very important topic to consider, especially when choosing a turbo upgrade.  Do you commute 20 miles to work and back daily?  Do you haul any toys?  Maybe you hotshot as a career, all these are some of the ways a driver uses his diesel truck.  A driver that tows a lot would best be suited for the Stealth 64, why?  It runs more efficiently at higher horsepower numbers while loaded.  The truck will sustain a heavy load for longer because the heat that the turbo is introducing is lower than a stock charger.  Lower piston temps, lower EGTs equals more time and a larger buffer before the truck is affected by the added heat.  

Single, Drop-In, 800 HP, LB7 Turbo:

When you're looking for the ultimate Duramax turbo, everything really depends on what caters to your wants and needs for your truck.  This turbo was created with diesel enthusiasts such as ourselves in mind. We asked what everyone wanted in a larger turbo and the Stealth 67 G2 is what we came back with. This new addition to the Stealth line is superb and fits in the family of our in-house designed, industry leading turbos. Let's delve into what this beast can accomplish. 

The Stealth 67G2:

• Quick spool up
• Big power
• Great daily driver
• Models available for 2001-2016 Duramax (LB7, VVT, LML)

We have lowered our MAP pricing on the Stealth 64 Turbo:

Calibrated Power, home of DuramaxTuner.com, has ramped up in-house production of the Stealth Turbo line.  This added capacity and volume of turbo production has provided an opportunity to lower MAP pricing on all Duramax models and allowed the Cummins 5.9L Stealth 64 to be a low price and top quality leader in it's category. 

Our Stealth 64 Turbo's are:

• Made in the USA!
• Upgraded, Drop-In Replacement!
• Quick Spooling with Big POWER!

Stealth 64 G2 Technical Information:

If you have an LB7 and are considering a replacement LB7 turbo, you want the best!  It has to be a turbo that is going to be reliable and meet your demands for performance.  You want something that is cutting edge, proven to work and a turbo that you can still drive or tow with everyday.  You need an upgraded LB7 turbo that is going to deliver.  And if you are looking for a Stage 1 LB7 turbo upgrade, you probably will look at the Stealth turbo line. 

Shopping for the best turbo means understanding what you need and what the turbo can do.  Here you can find the technical information about the Stealth Mach 1 (64) along with some insight as to what you should be looking for when shopping for an LB7 turbo upgrade. 

Other Articles About LB7 Turbo Options:

• LB7 Turbo Upgrade
• 6 Things to Know Before Upgrading Your Duramax Turbo
• How Much Boost Should My Stock Duramax Turbo Make

2003-2007 5.9L  DROP-IN CUMMINS TURBO:

After the extensive testing we did in the Cummins Turbo Shootout back in 2013 we learned a few things about Cummins single turbo systems.  This test featured 5 turbo's, recomended by the manufacturer, analyzed and compared side-by-side.  

If you read the article featured in Diesel Power Magazine or listened to the episodes we did at the Diesel Performance Podcast then you already know there was no clear 1 winner.  The reality of aftermarket turbo's is you have to sacrafice something to gain something.  So we set out to develop a turbo that could meet our requirements for being a great daily driver, good for managing EGT's while towing and something we could cause havok on the streets with.  

Cummins Stealth 64:

• Great Daily Driver
• Good for managing EGT's while towing
• Cause havok on the streets!

Duramax VVT Upgrades:

The 2004.5-2005 LLY was the first model Duramax to be equipped with a Variable Vane Turbo (VVT).  VVT  technology provides quicker spool-up, better EGT control, and better overall boost control.  This is also commonly referred to as a VGT or Variable Geometry Turbo. 

To understand the basics of a VVT or VGT technology take a look at this VIDEO on YouTube.

The stock Duramax VVT turbo from 2004.5 until 2010 is similar.  Slight changes to each model (LLY, LBZ and LMM) were made in compressor size, aspect ratio, blade profile and other features.  Despite these changes, you will find the same peak power potential of approximately 530 RWHP.  As a Duramax performance enthusiast this is probably just not enough power to keep your interest for long. 

There are many upgrade options on the market.  Deciding which one is the best for you can be tough.  An endless amount of forum threads and user stories makes it challenging to decipher fact from opinion.  

Stealth 64 Turbo Product Links:

• Stealth 64 LB7
• Stealth 64 VVT
• Stealth 64 LML

Scottsdale Duramax

This 1985 Scottsdale pickup truck started life with a 6.2L diesel motor.  That's right, the non-turbo, under-powered, over weight regular cab had a dismal 130 horse power from the factory.  

We love the body lines and nostalgia of these trucks.  The swap being partially done prior to it coming to us DuramaxTuner.com was an appealing feature to this build.  This provided a solid head start on a project truck we intended to use for testing.