Why You Should Consider the 3.0L Duramax Diesel for Your Next Sierra 1500

Time was when you had to go to a ¾ ton truck to get the efficiency and torque of a diesel, and it was often a large engine of 6 liters or more. But for the 2020 model year, GM developed the 3.0-liter turbocharged inline-6 Duramax diesel for its half-ton trucks, including the Sierra 1500. In doing so, it joins half-ton truck diesel offerings from both Ford and Ram, and it just might be the best engine choice for your next Sierra 1500 from Valley Buick GMC.

The 3.0-liter Duramax – also known as the LM2, was a clean-sheet design, not at all related to the existing 6.6 Duramax engine.  It was also a winner of the Wards 10 Best Engines & Propulsion Systems for 2020 – an award that did not go to its diesel competitors from Ford and Ram. Like most turbo-diesel engines, it is torque-heavy, producing 305 horsepower and 495 lb-ft of torque at 2750 rpm. That torque figure is key as it out-powers all of the available GMC gas engines, including the 6.2 Ecotec V8. Like those gas engines, it is paired with GMC’s 10-speed automatic. 

More Torque, Less Thirst

Efficiency is the other hallmark of diesel engines, and the LM2 does not disappoint. In 2WD form, it’s EPA rated at 24 city / 29 hwy / 26 combined. Each figure drops by two for 4WD. By contrast, the most efficient of the gas engines – the 310 hp 2.7 turbocharged inline-4 achieves 19 / 22 / 20 in 2WD as it produces 310 hp and 460 lb-ft of torque.

So the 3.0L Duramax is high in torque and is more efficient than gas engines. That is to be expected. But diesels also lack refinement and are noisy, right? That is where the LM2 benefits from its clean-sheet development which is foremost apparent in its inline-6 configuration. 

Strait-6 Smoothness

Easier packaging is the main reason carmakers prefer the V-configuration for their 6-cylinder engines.  A V-6 only needs room to accommodate 3.5 cylinders, whereas by its very description, an inline-6 needs room to accommodate 6 cylinders all in a row. But if you have the room, as the Sierra 1500 engine bay does, the inline-6 configuration has some distinct advantages. The primary advantage is lower vibration. That is because in an inline-six, each cylinder that’s undergoing a combustion stroke is balanced out by another cylinder that’s undergoing an induction stroke, and with these ‘paired’ cylinders often being located symmetrically around the center point of the crankshaft, there’s very little vibration generated by an inline six-cylinder engine as a result. A V-6 has no such inherent vibration. This is why the straight-6 configuration has been a favorite of BMW and Mercedes-Benz for decades. 

The absence of this vibration is even more pronounced in a diesel in which the components must be more robust to withstand the higher compression ratios. Combined with a moderate-for-a-diesel 15:1 compression ratio, the LM2 is a notably smoother engine than its diesel V6 competitors and even over the GMC 2.7L 4-cylinder, which makes it a much more pleasant truck to drive day-to-day. 

Refinement Throughout

The LM2 also features some very high-tech complementary starting with an aluminum block and cylinder head which significantly reduces the engine’s weight and improves thermal efficiency. The latter is further helped by Active Thermal Management, which uses a rotary valve system to distribute coolant through the engine in a targeted manner.  At start, it sends heat where it’s needed to warm up the engine, thereby reducing friction and heating the cabin. Later, it directs cooling where needed for high-power operation. With a similar goal, a variable oil pressure system also distributes oil more precisely based on rpm and load.

The 36,000 psi common rail fuel injection system features 9-hole nozzles that can fire up to 10 times per comparison ratio for a more thorough burn and even more smoothness. A variable intake manifold manages airflow based on rpm. Modern diesel ownership has also become easier thanks to improved DEF availability and cleaner emissions technology that support long-term performance and efficiency. 

All this adds up to a level of engine refinement that has the Sierra 1500 drive like a conventional engine yet with the torque and efficiency of a diesel. All for just a $1,545 premium over the 5.3 EcoTec3 V8. 

The 3.0L Duramax is available on the SLE, Elevation, SLT, AT4, and Denali trim levels. So, If you are interested in a new Sierra 1500 from Valley Buick GMC, toss out your preconceived notions of diesel engines and test drive a Sierra 1500 with the 3.0L diesel. It just might be the perfect engine for you.