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...

Over the years, GM has changed a lot regarding the turbos they use on Duramax engines. Not only have they changed manufacturers a handful of times but each RPO has its own unique measurements for key components. This can make it a headache when trying to track down exactly what the measurements of your stock turbo are. Luckily we've compiled this list of stock Duramax turbo specifications along with other helpful information so you can get a good idea of what you're already working with before you dive into the sea of turbo upgrades these trucks have to choose from. However, while some turbos may have the same peak power output, the size and shape of specific components can affect things such as exhaust gas temperature, drive pressure, and turbo efficiency range.  

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!

Stock Duramax Turbo Upgrades!

Duramax owners are generally proud of how their stock turbos perform.  They spool quickly, run hard and are capable of over 500 RWHP (once you tune it and make a few supporting modifications to handle the power).  However, after driving your truck around 520 RWHP for a while, the addiction will creep in and you may find yourself shopping for more power.  We all do it!  For some, it may not even be about more power, it may be about EGT control under load, or it may just be the factory turbo had an issue and needs to be replaced.  If you are anything like me, you will not want to replace it with the factory components if there is an upgraded, after market, charger available. 

Drop-In Duramax Turbo Options

In the old days, there was no such thing as a "drop-in" turbo.  You pretty much had to buy a turbo that was designed for a different application and convert it to run on your Duramax.  Meaning the requirements for installation included several custom fabricated pieces to make it work.  

As technology in the diesel performance industry has advanced, our options for parts have expanded.  No longer do we have to use semi turbo's and roal coal to make power.  Now with the common rail injection system and variable vane turbo advancements there is a real need to find a turbo that makes more power than stock, while retaining all the benefits of a stock turbo. 

Benefits of a stock turbo:

• Quick Spooling 
• Clean installation
• Reliable
• Serviceable by any dealer or reputable shop
• Requires no custom fabrication

However, they do lack peak power, and peak power matters!  When looking for which upgraded unit to replace the stock turbo, we recommend matching the replacement as close as possible to the desired power level to minimize compromising drive-ability.  Any extra capacity you buy in peak for performance will cost you low end response.  Example: Looking to make 650rwhp? Buy a turbo that can just barely squeak out 650rwhp, do not buy something that's good for 850rwhp because it will drive poorly a light load. 

Duramax engines have always come with solid turbos. However after miles and miles of whistling and boosting, your turbo may have problems. Or you may have other issues, that make you think your turbo has problems. This is very common as most drivers watch boost, keeping an eye on how much PSI they're making. It stands to reason that if your peak boost drops, your turbo has a problem. This is usually not the case though. More often then not, when we diagnose this symptom we find there are other problems leading to a lower than expected boost number. 

Target boost numbers for the following RPO's are as follows (PSI)

2001-2004 LB7- Stock 20-22, tuned 24-26, tuned with PPE boost valve 28-31.  Failure will occur near 34psi

2004.5-2016 Stock 22-24, Mild tune 27-28, Hot tune 33-35

The factory map sensor which electronically measures boost on a 2001-2004.5 trucks only reads to 22-24 psi, 2006-2016 MAP sensors read to 37 psi.  If you want to read boost numbers higher you'll need an aftermarket gauge.