GMC’s 2017 Sierra HD range has been expanded with the addition of the firm’s redesigned Duramax 6.6-liter turbo-diesel V8.

Now more powerful than ever, the new Duramax V8 will replace the existing unit in GMC’s range and is promising improved refinement thanks to its new construction and selection of updated features.

On the statistical front, the engine pumps out 445 hp and 910 lb-ft of torque, a 19 per cent torque rise over the existing V8. Impressively, 90 per cent of the unit’s torque is available at a low 1,550 rpm until 2,850 rpm, making the Sierra HD particularly useful for towing.

To achieve the additional power and torque, GMC has gone to town with the engine. For starters, there is a new cylinder block and cylinder heads, increased oil and coolant-flow capacity, updated electronically-controlled turbocharger, a different solenoid fuel system, B20 bio-diesel compatibility and a full-length damped steel oil pan and refined rocker cover, two elements that make the engine quieter than the old unit. Elsewhere, the camshaft profile has been altered, further aiding in the greater power.

As previously detailed, this engine comes complete with a bespoke air intake system that necessitates a prominent hood scoop being installed.

PHOTO GALLERY