The Duramax diesel engine project started in 2001 as a joint venture between GM and Isuzu. Since then, all generations of these engines are known for their reliability and power. Every generation had different engine codes, making it difficult to tell them apart. But, once you learn the Duramax chronology it is not that hard to understand these engines.
So, what does LBZ Duramax stand for? The LBZ V8 diesel engine was made between 2006. and 2007. but is still renowned for its overall quality and performance. It is used in pickup trucks and has a 6-speed Allison transmission. Like all engines, the LBZ has weak spots, like piston failure problems and leaking transmission. Nonetheless, these engines are still very popular and widely used in the US.
We wanted to base one whole article on this legendary engine. So, you will learn the origins of these engines, their pros and cons, and also how to upgrade them. We will not forget to point out the weaknesses of these engines, so you will know what to look out for. Enjoy!
Origin Of The LBZ
The LBZ is the third generation of Duramax engines. They bring a whole lot of power and torque to the table. Also, these engines used the common rail injector. The LLY engines received a larger turbocharger that released more power. That turbocharger was replaced with the smaller one in the LBZ.
The LBZ had several common issues, such as glow plug failure, overheating problems, and EGR issues. Also, the fuel pressure valve is a common problem. But, the biggest issues were the faulty fuel injectors and the head gasket failure.
This engine was short-lived and was produced just for a year. That doesn’t mean the LBZ is a bad engine, but the emissions requirements became much stricter at that time. The next Duramax engine focused on reduced emissions values. These emissions regulations limited engines and their power. That is one of the main reasons for the popularity of this engine 15 years after production stopped.
For further information about fuel injectors and their maintenance, we recommend reading an article about checking injector balance rates.
LBZ Duramax Specs & Features
Some basic and most important LBZ specs are:
- Engine design: 90-degree V8
- Stroke: 3.90 inches
- Bore: 4.06 inches
- Displacement: 6.6L
- Compression ratio: 16.8:1
- Engine block: Deep skirt made of cast iron
- Horsepower: Maximum output of 360 at 3,200 RPM
- Torque: 650 pounds/foot at 1,600 RPM
- Injection system: Bosch high-pressure common rail direct injection.
The engine bay and its cast iron block remained from the previous engines. The aluminum-made heads also remained, but all these components received an upgrade. Cylinder bore bottoms are upgraded through improved casting and machining changes in the cast iron block. The LBZ also got a new reluctor wheel. With it, the ECU gets the accurate crankshaft position.
Bearing regions of the block are prepared for additional horsepower and torque. Using improved bearing material increases durability, allowing the engine to handle tuning better. Bearing caps were made taller, and 4 mm deeper bores were made for the main cap bolts. The crankshaft was also updated and made of forged steel together with the connecting rods.
The LBZ is the last engine that offers both manual and automatic transmissions. The buyers could choose between a 6-speed automatic Allison or a 6-speed manual ZF-650 transmission. It is often questioned are all Duramax engines paired with the Allison transmission.
For more about that topic, you can read our article about Duramax engines and Allison transmissions.
Pros/Cons
Pros
- Stronger block and most components of the engine
- Better tuning capabilities
- New 6-speed Allison transmission
- Improved performance
Cons
- Some issues from older engines remained
- Problems with pistons
- Leaking Allison transmission line.
What To Look For Before Purchasing
These engines are well-known and still in massive use. Some problems are connected to stock parts like gaskets and pistons. If the engine passes more than that, those problems are usually resolved. Pay attention to the water pump, the condition of the EGR valve, and the transmission lines.
Reliability of LBZ Duramax
Several issues with the older Duramax engines are resolved, granting the LBZ improved reliability. It is a sturdily made engine that can take much tuning and has a long work life. If regular maintenance is done on time, this engine can last long. Pay attention to the fuel and oil quality, and change filters and oil regularly.
Common LBZ Upgrades
The most common LBZ upgrades are to the Bosch CP3 injection pump. It was updated to an all-new, seven-hole fuel injector. That raised the maximum pressure from 23,000 psi to 26,000 psi. Also, a larger turbocharger is often used to replace the stock Garret turbo. Besides those, there are other options that you can use to maximize the power output.
Crankshaft Pin Kit
This kit reinforces the mounting of the crankshaft damper to the crankshaft nose. It can be used to repair the stock part or to upgrade the existing one. These pins can cause catastrophic damage to the engine, which can be prevented with this kit.
Programmer
Using a tuning kit, a “chip,” or a programmer is now a must-do for all who want to improve their Duramax truck. You can start adding horsepower and torque with the help of a tuning kit. But, if you want to add more than a hundred or so horsepower, you must upgrade stock components.
There are a lot of tuning kits on the market, with different options and capabilities. Depending on your needs, you can significantly increase horsepower with these kits.
Radiator
If you want to resolve performance issues, you will need to upgrade the radiator. Increased horsepower and torque will demand a better cooling system.
Lift Pump
When you add components that demand additional high-pressure fuel, the stock common-rail injection will not be enough. Then you need to think about installing a higher-pressure pump. There are several options for installing a lift pump on your LBZ
Delete Fuel Filter
Before you decide to delete the Duramax factory fuel filter, installing a lift pump and a fuel/air separation system is recommended. This system allows unrestricted fuel flow to the engine.
Turbo Inlet/Intake Mouthpiece
You get an additional 10-15 hp with an improved intake mouthpiece. It lowers the exhaust temperatures and turbo spool-up times. It also increases throttle response and allows the engine to work at lower temperatures. This is especially important for tuned-up engines.
Air Intake System
The main problem with the LBZ intake system is that it takes air from above the engine bay. The point of the air intake system is to get additional air from below the engine, closer to the bumper. There, the air is colder, which is required for high-end air intake systems. You can choose between open-air and closed-box intakes. Choosing either of those is a good pick. With this, you can expect a 20-50 hp gain.
Exhaust
There are several reasons to upgrade the stock exhaust option on the LBZ, even if you are not among diesel enthusiasts. The most obvious ones are increased power, improved fuel efficiency, and lower exhaust gas temperatures. Depending on the model, you can also expect a better new sound.
Upgraded Tie Rods End or Sleeves
This upgrade is recommended for users that love to use their diesel trucks for off-road purposes. They can reinforce factory tie rods and prevent them from bending. Even the smallest bend will eventually lead to breaking.
High-Flow Exhaust Manifold for the Drivers Side
A stock driver’s side exhaust manifold has a big dent that impacts exhaust flow. An improved exhaust manifold maintains full factory diameter up to the up-pipe. This will also add value to the factory performance of the manifold.
What Are The Common LBZ Duramax Problems
The first two generations of Duramax engines had their share of problems that needed to be resolved. Then came the LBZ that tried to annul them. The large LLY turbocharger that caused overheating issues was downsized. Despite that, the engine produced higher power levels and more torque.
Some problems from earlier versions remained. Those include problems with cracked pistons, the EGR and glow plug problems, and the water pump failure. The steel head gaskets after 100k also tend to get cracked, leading to coolant leaks.
The problems with low fuel pressures in those trucks with engine tuning are worth mentioning. The mentioned direct injection fuel system couldn’t handle the increase in power. The lack of a fuel lift pump caused problems, and the owners had to install an additional fuel pump.
Damaged LBZ Pistons
The LBZ still used cast aluminum pistons which made them prone to cracking. This risk increases when the engine undergoes extensive tuning operations. These pistons also lowered the compression ratio. These pistons usually crack before hitting the 100k mark, so most Duramax engines have this problem resolved.
To avoid problems with pistons, use quality fuel and coolant liquid. The main symptom of damaged pistons is excessive smoke coming out of the tailpipe, combined with a drop in performance.
Check Out Common Problems With LBZ Duramax:
Duramax EGR Problems
The LLY is the first Duramax with the EGR system implemented. The EGR valve conduct exhaust gas recirculation and a part of the exhaust gases back to the combustion chamber. This way less harmful gasses end up in the atmosphere. This system causes different problems when it becomes dirty and worn. The engine loses power, and sometimes it is hard to start it. Acceleration is also an issue.
Failed Duramax LBZ Water Pump
The water pump problem plagued the Duramax engines from the beginning. These water pumps use a plastic impeller which is not durable as the one made of iron. The impaler wears over time, causing a leak. In the long run, that will cause lower engine coolant levels and often overheating. That is why you need to check the water pump, and engine coolant levels regularly.
Damaged Glow Plug
The problem with glow plugs remained from the previous LLY engines. Plugs were paired with bad modules. These modules often overload the plugs with electricity. When that happens, the plugs can brake off and cause extensive engine damage.
Leaking Allison 1000 Transmission Line
The problems with the leaking Alisson 1000 transmission line started with the LBZ. There are several moving parts in the transmission, and if any are worn or damaged, that can cause a leak. A transmission fluid leak in time will make your truck undrivable. Once you notice a leak under your truck, visit a mechanic.
FAQs
Is the LBZ a good Duramax?
The LBZ is considered to be one of the best Duramax engines up to date. The best proof of that is the constant demand for these engines, even after 15 years. They don’t have the limiting emission controls features like newer Duramax engines. Also, they can be tuned to be a real monster engine.
Is the LBZ Duramax a V8?
Yes, it is a V8 engine with a 6.6L displacement.
How much HP is an LBZ?
The stock LBZ has an output of 360 horsepower. That is a significant increase from the previous LLY Duramax, which has 310 horsepower.
How do I know if I have an LBZ or LLY?
There are several differences to look out for. LBZ, for a start, has better performance. It has more horsepower, torque, and maximum engine speed. The LLY has a significantly larger turbocharger (91.78mm vs. 88.25mm), and they have different fuel injectors. Maybe the most obvious difference is in the VIN. In the 8th position, the LLY has the number 2, while LBZ has the letter D.
Final Considerations
If you are considering buying a truck with the LBZ engine it is hard to make a mistake. Look out for pistons, gaskets, and the water pump; you should be good. These engines are reliable and offer a lot of space for improvement.
These engines don’t have strict emissions requirements like the newer Duramax engines. This makes them the perfect choice for performance enthusiasts. For more Duramax news and tips, stay with us!
