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.
What's an RPO? Crucial Duramax Information!
This article will help you understand what an RPO is, how to find yours and when it will be needed. An RPO or Regular Production Option is a GM-specific code, made up of 3 characters, that helps the manufacturer specify what configuration of options has been or needs to be applied to a vehicle. This can include anything from paint color to powertrain options. For Chevy/GMC Duramax trucks each type of engine can be signified by a different RPO code.
The Six Speed Conversion Kit from duramaxtuner.com has been unleashed and it’s a proven winner. The fifth gear days of yore have passed the world by and the 2001-2005 LB7 and LLY owners are loving how much more the extra gear brings them. Large amounts R&D and testing has given 5 speeds a better shift schedule and the highest quality 5-6 and 6-5 shifts. The upgraded valve body with have your aging truck shifting like a new model.
5 to 6 Speed Allison Conversion:
The Allison 1000 transmission equipped in the 2001-2005 HD Silverado and Sierra was considered to be revolutionary when it was released.
Owners rave about the smoothness and reliability of the 5 speed Allison transmissions. They're able to reliably handle the strain of towing heavy and still have reasonable street manners for commuting. Duramaxtuner has recently invested considerable time into the AL5 controller to build out the shift shedule and quality of all the 5-6 and 6-5 shifts. Matched with our upgraded valvebody this kit will have your 15 year old truck shifting like a 2018 model.
As most technology has advanced over the last 12+ years, so has transmission technology. You've probably noticed that just about everything on wheels has more gears these days. Starting in 2006 all Duramax powered GM trucks were given an extra overdrive gear (.61). Since then, they haven't looked back.
Why is that? Why does your truck need more gears?
Benefits from more gears:
- MPG improvement
- Noise Reduction
- Parts Longevity
- Narrower Cruise range to meet Emissions Requirements
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:
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:
Essential 2004.5 and 2005 Duramax Upgrades
LLY is the code used for Duramax motors used in 2004.5 and 2005 HD trucks. Although they introduced improvements from the 2001-2004 on the LB7 motor, there are a few essential upgrades every owner should consider. (That is assuming an LLY owner would want more power, lower EGT's and better efficiency.)
Before diving into the pitfalls of an LLY, here are a few of the improvements brought to market when they were released.
- Injectors outside of the heads provided much easier replacement
- Improved injector design much more reliable than its predecessor
- Variable Vane Turbo technology provides better spool up and wider power band
- Largest frame turbo of any Duramax motor to date
After years of testing this motor and countless upgrades, there are at least 5 essential upgrades every LLY could use.
What is the the best tool a diesel enthusiast could ever ask for; a Mustang 4WD Chassis Dynamometer. Why is that? An 4WD Chassis Dyno gives you the ability to see exactly what your truck is capable of. It also provides tuners the safe and controlled enviroment required to test calibrations and dial in your truck to best running condition. Which in turn, gives you a truck that not only makes big power, drives as smooth as possible and gives you insight to when and how your truck performs at it's best.
- Find your PEAK Horse Power and Torque
- Get the smoothest running truck possible
- Gain insight into how and when your truck performs it's best
Many people have estimated horse power and torque numbers based on what someone else has told them. A Chassis Dyno gives you the ability to know exactly how much power you have at the wheels. No guessing or estimating involved since a dyno is a measurement tool at it's core.
Beyond peak power, there is drive-ability to consider when you have a heavily modified truck. Any tuner can make the peak power number, the difference between them is how the truck drives on the street. Smoke output, shift points, throttle response and so much else can be dialed in when you are strapped to a dyno for testing.
Diesel truck owners often want more RPM. The logic here is that RPM equals power. However, a chasis dyno gives you a clear picture of where and when your truck makes peak power. When it comes to competing with your truck, this is crucial! Diesel guys know all too well how close sled pulling or drag racing can be, so every possible edge really matters.
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.
The LLY Duramax is a great truck from the factory for there are 3 modifications every owner should make! The LLY was manufactured 2004.5 and 2005. There are a few 2006 models that are labeled as an LLY, however they have all of the LBZ upgrades from the factory, so for performance applications consider those an LBZ. An LLY was the first Duramax with the injectors outside of the heads, a variable vane turbo and a 50 state EGR.