An evolution of the company's long-used straight-five Volvo Modular engine, which itself is an evolution of the Volvo B6304 straight-six engine, the SI6 can be mounted transversely for front wheel drive or all wheel drive applications.

Despite the added cylinder and displacement, the engine remains compact, and is in fact 1 mm (0.039 in) shorter than the previous straight-five.

Both offered variable cam timing, though only the turbo version varies both the intake and exhaust valves.

Production of the Volvo SI6 began at the Ford Bridgend Engine Plant in Wales in May 2006.

[9] In its PZEV version power output is reduced to 172 kW; 231 hp (234 PS) and produces 300 N⋅m (220 lb⋅ft) of torque.