How do I know if I have LBZ or LLY? So, you own a Duramax and you can’t seem to figure out if what you have in your possession is LBZ or LLY.

Well, that’s what we’ll cover in this article.

Ready? Let’s get into it.

Table of Contents

How Do I Know If I Have LBZ Or LLY?

The Duramax Diesel has been around for a long time. It was first introduced in 2001 and has had many improvements since then. There are two different generations of the Duramax, LBZ (2002-2007) and LLY (2008-2014).

The LBZ is known for having problems with head gaskets and turbo bearings. The LLY has lower emissions than the LBZ but also has some issues with injectors and turbo bearings.

Both engines have common problems like cracked heads, camshafts, oil pump shafts, intake valves, fuel injectors, turbochargers and more.

Is My 2006 Duramax LLY Or LBZ?

Here are a few ways to tell the difference between an LLY and LBZ:

The LLY is a single turbo with a 3.0L displacement, while the LBZ is a twin-turbo with a 3.7L displacement.
The LLY has an EGR tube (part #799056) connecting the intake manifold to the exhaust manifold, while the LBZ does not have this tube.
The dipstick on an LLY is located on top of the block, while it’s located at the bottom of the block in an LBZ.

Can You Put A LBZ In A LLY Truck?

You can put a LBZ but it will not be a direct drop-in without any swapping. You will have to swap out the ECM, 6-speed transmission (05 has the 5 speed and the 06 has the 6 speed).

You will also have to swap out the front end as well as some other minor things.

The motor mounts are different between the trucks so you will either have to make new mounts or use one from another vehicle that is compatible with the LBZ engine.

The tranny mount is different between 05-06’s and 07-14’s so you’ll need an 07-14 mount or modify your existing one.

Are LBZ And LLY Blocks The Same?

The quick answer is no. They are not the same.

The long answer is that the two blocks are very similar in design and construction, as both are aluminum four-valve pushrod engines with deep skirt cross-bolted main caps. The cylinder liners on both blocks are also made by Mahle, a subsidiary of General Motors.

The differences between the two blocks begin with the main cap size, which is larger on the LBZ than on the LLY. The main cap circumference on an LLY is 3.9 inches while the LBZ cap measures 4.5 inches.

The reason for this difference is that GM used a longer stud (with more threads) when building the engine than they did when building the LLY block – so that it would fit over their new crankshaft’s longer snout diameter.

The other difference between these two blocks is that if you buy an LLY block from GM now, it will come with a standard oil pump pickup tube – but if you buy an LBZ from GM now, it will come with a small pick-up tube that goes into the front of your timing chain cover (and which requires an aftermarket oil filter).

What Year Is A LBZ Duramax?

The LBZ Duramax was first introduced in 2006, and it’s still being used today. The LBZ Duramax is found in GMC Sierra HDs and Chevrolet Silverado HDs.

The LB7 Duramax was introduced in 2001, and it was the first generation of diesel engines for the Silverado. The engine had a 4.5L displacement and featured common rail injection technology. The engine was used until 2006 when it was replaced by its successor — the LMM Duramax.

Are All Duramax Blocks Interchangeable?

The answer is no. There are two different block designs for the Duramax engine, and they are not interchangeable with each other or with the older versions of the diesel. The 6.6L block appeared in 2006, while the 6.5L block was introduced in 2010 and is still in use today.

The 6.6L blocks have a larger oil pan than the 6.5L blocks and also have a wider main bearing cap bolt spacing to accommodate larger pistons. The main caps on both engines have six bolts instead of four like older diesels, but the 6.6L blocks have seven main cap bolts total compared to six on the 6.5L block (four under each head).

Both blocks can handle up to a 420-pound-foot torque rating as well as up to 1,000 horsepower at 6,800 rpm and 1,200 horsepower at 7,100 rpm when used with a manual transmission or an automatic transmission that has overdrive ratios available above 4th gear.

How Much Horsepower Does A Stock LLY Duramax Have?

The stock LLY Duramax is a great engine and has a lot of power. It makes around 325 horsepower and 400 lb-ft of torque. This is a very reliable engine and can be used in many different applications.

The main advantage of the LLY Duramax is that it has an electronic governor that allows for better fuel economy and more horsepower than the LB7 or LMM Duramax engines. The LLY is also lighter than other 6.6L Duramax engines, which makes it easier to tow with while still having good power.

The downside of the LLY Duramax is that it costs more than other 6.6L Duramax engines because of its advanced computer system and lightweight design. For those who need something inexpensive, there are better options such as the LB7 or LMM Duramax engines.