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. 

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!