The engine block is still made from cast iron. That increased its displacement to 6.7 liters (408 cubic inches). The 6.7 ISB had an increased cylinder bore (4.21 inches or 106.9 mm) and piston stroke (4.88 inches or 124.0 mm). The market wanted a new engine for medium-duty trucks and buses, and the ISB 6.7 engine became the answer for that.
At that moment, it was outdated and depleted the limits of possibilities for improvements in terms of fuel consumption and emissions.
Its predecessor, the ISB 5.9, has been produced almost ten years.
