LB7 Vs LBZ- The Complete Comparison Guide!

You’ve probably heard of your engine’s RPO numbers, that is where the LB7 and LBZ come from. The RPO stands from the Regular Production Option, but what is the difference between LBZ and LB7?

The main difference between the Duramax LB7 and LBZ is that the LB7 has 300 horsepower and 560 lb-ft of torque and a fuel tank capacity of 26 gallons. In comparison, the LBZ has 360 horsepower and 650 lb-ft of torque, and a fuel tank capacity of 34 gallons.

But is that all about the LB7 and LBZ difference, or is there anything else you need to know? Well, there are a few other differences between these two Duramax. Make sure to read this article correctly, as we will break down all differences in our LB7 vs LBZ comparison.

LB7 Vs LBZ Table Comparision

Torque650 lb-ft at 1600 rpm560 lb-Ft at 1600 rpm
Compression Ratio16.8:117.5:1
Power output360 bhp at 3000 rpm300 bhp at 3200 rpm
Model (Years)2006-20072001-2004
Fuel TypeDieselDiesel

In our comparison between LB7 and LBZ, we will include everything you need to know about these two Duramax engines. Read below to learn all the LB7 vs LBZ differences.

However, another difference is the LB7 vs LBZ years. LBZ was active from 2006-2007 and LB& from 2001-2004. But there are many more that we will see below. So, what are we waiting for? Let’s get straight down to the comparison.


When it comes to mileage or LB7 vs LBZ mpg, the LB7 outperforms the LBZ by a significant margin. The LB7 gets 17 to 18 miles per gallon in the city and 19 to 21 miles per gallon on the highway.

The LBZ, on the other hand, can get 15 to 16 mpg in the city and 17 to 20 mpg on the highway.

Engine Power

The LB7 vs LBZ power also sees a difference. You’ll see that the LB7 and LBZ engines both have a 6.6-liter displacement. However, the power supply is not identical. The LBZ Duramax engine is the most powerful of the bunch, providing more power and torque at lower RPMs. It produces 360 horsepower at 3000 revolutions per minute.

The LB7, on the other hand, is the older of the two, with a power output of 300 horsepower at 3200 rpm.

Moreover, the torque also plays a vital role in the total power. LB7 has a 520 lb. ft. rating. At 1600 rpm, LBZ has the greatest torque of 605 lb. ft.

Build Quality

The configuration of the LB7 and LBZ Duramax engines is identical. These engines have a V-8 arrangement, which means they have eight cylinders. The cylinders are separated into two banks in a V-shaped design arrangement and share a crankshaft.

Tuning Impacts

LBZ and LB7 are highly tuneable, making them a perfect choice for any car project. The LB7, like the LBZ, is a tuner’s dream, but it has its limitations.

When this engine is tuned, it is the only time it starts to have issues. The pistons are likely to crack if the engine is adjusted above 700 horsepower. Some claim that this amount is closer to 500 horsepower. The Alison transmission sliding is another typical concern associated with tuning.

Also Read: 5.9 Magnum Vs 5.7 Hemi: Which Is More Suited For You?

So if you wish to tune them, the limit is around 500HP. In LB7 vs LBZ race at 500HP, the LBZ will easily defeat the LB7 engine.


When comparing LB7 vs LBZ sound, both of them have nearly identical sounds. Obviously, both of these engines are V8 with the same 6.6-liter displacement capacity. However, the sound of LB7 is slightly louder than the LBZ.


Keep in mind that both of these engines are very durable. But in comparison, your best bet would most likely be the LBZ. They’re all dependable if properly maintained.

Towing Capacity

On average, the LB7 vs LBZ towing capacity is more in LB7 with a capacity of 14.800 lbs, and for LBZ, it is 12,000 lbs.


The price of a new LB7 would be in a range of $15000-$25000 depending on what other specs you need, and a typical LBZ would cost around $25000-$30000.

A Helpful Tutorial You May Need!

Frequently Asked Questions (FAQs)

What is the difference between LB7 and LBZ?

Compared to the LB7, the LBZ is a little quieter. The LB7 outperformed the LBZ in terms of mpg. However, the LBZ is a six-speed Allison instead of the five-speed LB7. As a result, boosting the LB7to LBZ power levels is simple.

Is the LB7 the best Duramax?

The 6.6L Duramax LB7 is the best diesel engine overall. The LB7 Duramax was introduced in 2001 and outperformed Detroit, signaling a dramatic shift in the diesel market for Chevrolet pickup trucks and GMC automobiles.

Is the LB7 or LLY better

LLY engines are generally more powerful than the LB7, producing 300 horsepower at 3200 rpm. LLY from 2004 is rated 310, whereas the latter version has a lesser output of 250 horsepower. Output Torque The LB7 engine has a torque rating of 520 lb. ft. at 1600 rpm, whereas the LLY engine has a torque rating of 590 and subsequently 460 lb. ft. at 1600 rpm.

Are LB7 fast?

Ultimately, the LB7 is a good competitor for earlier diesel engines, and it is the fastest of all the Duramax engines.


In our LB7 vs LBZ comparison, we broke down all the essential features of both of these engines. We’ve listed the primary advantages and disadvantages of each engine. Which one you choose depends entirely on you. They’re both powerful engines with a lot of potentials.

But, for us, the LB7 is the one to go for. It could be a dream for any mod or project car lover. This is all because of the immense power it can produce.

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D Conroy

Meet our senior writer and content manager of Automasterx. He has worked in several mechanical garages and mastered different vehicle diagnoses and parts repair. He never stops until finding out the ultimate solutions for any vehicle fault code. However, ensuring the only solid solutions for each vehicle malfunction is his core part of the duty, alongside analyzing fault codes and signals.

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