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2017-2023 Duramax 6.6 L5P

The L5P Duramax is the latest version of GM's V8 diesel engine, and it is a true powerhouse. Introduced in 2017, this engine code-named Y is the most powerful diesel engine that GM has ever produced, with a whopping 445 horsepower at 2,800 rpm and 910 lb-ft of torque at 1,600 rpm. Let's take a closer look at the L5P Duramax engine and see what sets it apart from its predecessors.

First and foremost, the L5P Duramax engine is not just an upgraded version of the previous LML Duramax. In fact, it hardly resembles the old LML at all, except for the displacement. While the exterior of the trucks that use this engine may look similar to the LML Duramax, the L5P engine is vastly different under the hood.

The L5P Duramax engine uses a 90-degree V-8 configuration, with a cast-iron block for superior strength. The cylinder walls are induction-hardened, and the engine has five nodular main bearings for even greater durability. The engine block also features a deep-skirt design with four-bolt, cross-belted main caps, which bolsters the block and allows for more accurate location of the rotating assembly.

In addition to the cast-iron block, the L5P Duramax engine has a die-cast aluminum lower crankcase that serves as the lower engine cover, while also providing additional strength to the block. This design has helped GM achieve weight savings as well.

One of the major changes that set the L5P Duramax apart from the LML Duramax is the significantly bigger crankshaft rod journals. These larger rod journals allow for the use of a stronger crankshaft and more bearing area to sustain higher cylinder loads. The rod journals are cut-then-rolled, strengthening the journal-web connection. The crankshaft itself is made of forged micro-alloy steel, adding to the engine's durability.

The connecting rods of the L5P Duramax engine are also different from the LML. They are forged with a powdered steel alloy and a fractured cap design, with a 45-degree split-angle design that allows larger diameter rod bearings to pass through the cylinder bores during assembly.

Overall, the L5P Duramax engine is the most capable Duramax to date, producing an impressive 445 horsepower and 910 lb-ft of torque in stock form. This was achieved through a number of big changes, including a BorgWarner Variable Geometry Turbocharger, a fuel system overhaul, and a fully-functional hood scoop intake system. These changes resulted in a 48 horsepower and 145 lb-ft of torque increase over its predecessor.

The L5P Duramax engine is an engineering marvel, with numerous big changes that set it apart from the LML Duramax. It is by far the most capable Duramax engine to date and a testament to GM's commitment to producing powerful and reliable diesel engines. Whether you're hauling heavy loads or simply looking for a truck with impressive performance, the L5P Duramax engine is definitely worth considering.