Scania launches Super-11 engine with VVT

Scania has launched a new 11-litre truck engine to fill the gap in its range between the nine-litre, five-cylinder unit that tops out at 360 hp and the six-cylinder Super 13, 13-litre unit, whose outputs start at 420 hp.

Crucially for maximum payload operations, the new Super 11-litre six is up to 85 kg lighter than the 13-litre, while being a claimed seven per cent more fuel-efficient than the 360 hp nine-litre.

Much of the engine layout and up to 85 per cent of the componentry of the new Super 11-litre is shared with its 13-litre stablemate, including a one-piece cylinder head mounting double overhead camshafts (DOHC), and it comfortably fits into the lineup with outputs of 350, 390 and 430 hp. Respective torque outputs are 1,800, 2,000 and 2,200 Nm.

For the first time in a Scania engine, the DOHC layout is exploited by variable valve timing (VVT): hydraulically-actuated cam phasers can independently adjust inlet and exhaust valve opening and closing points against crankshaft position to suit operational conditions. This allows optimisation of thermal management and combustion performance, which will be particularly important when Euro 7 emissions limits come into force as well as assisting attainment of VECTO fuel consumption targets.

Scania had hoped to introduce this variable valve timing on the Super 13 engine, but it is understood initially met with problems where the variations of camshaft torque caused by spring compression and extension triggered undesired phase oscillations and disrupted timings. These have apparently been resolved with the 11-litre engine.

VVT can be used to hold the intake valves open during the first part of the compression stroke to achieve ‘Miller timing’ as DAF has done with its new 11 and 13-litre engines (Transport Operator 130), which boosts the engine’s expansion ratio compared to its compression ratio and can improve fuel consumption by up to five per cent. It also allows Scania to use ‘Jake brake’-style compression engine braking, reducing the requirement for a transmission retarder and thus saving further weight and cost.

Adjusting exhaust valve timings for earlier opening can assist in the warm-up and temperature control of exhaust aftertreatment systems. VVT can also be applied to both camshafts simultaneously to reduce overlap, boosting internal exhaust recirculation and reducing NOx production where required.

Further NOx control is provided by introducing AdBlue into the exhaust stream at the turbocharger, meaning that the selective catalytic reduction process can commence sooner after a cold start than with a conventional layout.

Driver comfort is improved and mechanical stress reduced by the addition of engine balance shafts, while maintenance intervals are extended by up to 30 per cent over the nine-litre engines. New engine management software has also been introduced.

The new 11-litre engine is compatible with HVO, while the 390 and 430 hp versions can be supplied prepared for use with fatty acid methyl ester (FAME) biodiesel, giving operators the opportunity to lower their carbon footprint through reduced fossil fuel use.