Groundbreaking in the 9-litre class: The MAN D1556 diesel engine for off-road applications. This straight-six power unit delivers between 205 and 324 kW (279 and 440 HP). Its highest power variant achieves a maximum torque of 1,970 Nm at speeds between 1,150 and 1,300 rpm. Even at low speeds, the MAN D1556 delivers high torque. And with a dry weight of just 860 kg, it is the lightest off-road engine in its displacement class. “With the D1556, the MAN Engines engineers have succeeded in developing an engine with high power density and compactness that is perfectly suited to off-road application requirements. In addition, as the first 9-litre engine developed by MAN Engines, it completes our engine portfolio for construction and agricultural machinery and bridges the gap in performance between the well-established MAN D0836 series with 6.9-litre displacement and the D2676 with 12.4-litre displacement,” explains Hubert Gossner, head of off-road sales at MAN Engines.
MAN Engines offers the most individual solutions for engine integration into the machine in order to perfectly adapt the engine characteristics to application and load profiles and thus ultimately to differentiate it from the competition among machine manufacturers. Solutions can be of a mechanical nature such as weight-saving plastic oil pans or oil pans with load-bearing structure, electronic adaptations via the engine control (EDC), or features that are even reflected in the machine concept such as electronic immobilisers. The modern engine control unit architecture also allows software optimisation of a wide range of torque and power characteristics, as well as full integration into the machine. Diagnostic functions relevant to the engine can also be easily implemented and integrated into the customer’s own systems. The auxiliary units – such as alternator, air-conditioning system or air compressor – are also modular and can thus be optimally designed for different installation situations and customer interfaces. Furthermore, the use of up to three PTOs is possible, for example for hydraulic pumps.
The broad power and torque plateau of the D1556 is attributable to the turbocharger with its variable turbine geometry (VTG), as well as the common-rail system which ensures injection pressures of up to 2,500 bar. Based on these technologies, the power unit with its bore of 115 mm and stroke of 145 mm develops its power uniformly and dynamically, even in the lower speed range. The high compression ratio also results in more efficient fuel combustion, which – together with the modern engine design – leads to incredibly low fuel consumption levels across the entire engine map range. Further advantages of the VTG turbocharger lie in the wide range of deployment profiles and in its compact design which makes it an ideal fit within the overall D1556 concept. Its overall dimensions of 1,414 x 807 x 1,103 mm (length x width x height) mean the 6-cylinder engine has one of the lowest installation volumes on the market. This offers an ideal opportunity for designers to perfectly integrate the engine into construction machines such as excavators, wheel loaders and mobile cranes or into agricultural machines such as tractors, forage or combine harvesters.
The MAN D1556 meets the latest requirements for emission standards such as EU Stage V as well as US Tier 4. At the same time, the new MAN engine also offers options for complying easily and cost-effectively with EU Stage IIIA/IIIB limits for countries with less stringent specifications. The key to this is MAN Engines’ modular exhaust gas aftertreatment system with a wide range of interchangeable components and packaging options. These essentially consist of the two assemblies DOC/DPF (Diesel Oxidation Catalytic converter / Diesel Particulate Filter) and SCR (Selective Catalytic Reduction) with mixer for EU Stage V and US Tier 4. For the emissions downgrade to Stage IIIA/IIIB level for countries with other emission standards, only the assembly with SCR is used. This flexible system allows off-road machine manufacturers to offer their products around the globe – without changing the installation conditions for the basic engine. In general, the MAN D1556 uses an SCR-only system without separate exhaust gas recirculation, which saves space and reduces the complexity of the system. The exhaust gas cooling from approx. 500 °C to approx. 70 °C, which the EGR module usually has to perform, is no longer necessary. Therefore, less cooling power is required and a smaller cooling system can be installed. Due to the reduced cooling power requirement, the fan power is reduced so that the overall efficiency of the system increases. The airless dosing of the urea solution saves additional space and technical effort and thus reduces the installation volume of the system, which can be installed flexibly anyway.
With the MAN D1556, MAN engineers have developed a new diesel engine that is characterised by maximum reliability. Basis for this achievement is MAN Engines’ decades of field experience with various installation situations and load profiles in the off-road sector, as well as the knowledge transfer from other MAN engines of the latest generation. Established materials and field-tested technologies from the MAN commercial vehicle engine large-scale production ensure the quality standard – as does MAN’s own development and production in the International Engine Competence Centre in Nuremberg. In addition, design details such as insulation measures on the exhaust system provide advantages when used under dusty and hot operating conditions. Reliability is also supported by the reduced complexity of the engine without exhaust gas recirculation (SCR only) and by an exhaust gas aftertreatment system (AGN) control fully integrated into the engine control unit. Downgrade versions have a higher sulphur compatibility and can therefore also be used worldwide in countries with sulphur contents of up to 2,000 ppm in diesel. This facilitates secondary marketing in non-European countries, where higher sulfur content is often permitted in diesel fuel. Service options such as extended warranties provide additional convenience in after-sales service. A proven, worldwide and close-knit MAN service network as well as international on-site support by MAN’s own engine specialists is available.
|Engine height over crankshaft
|Number of cylinders
|Common rail (2,500 bar)
|Type of injection pump
|DENSO common rail pump
|Direction of rotation looking at flywheel
|Rated power according to UN ECE-R120
|205 – 324 (279 – 440)
|1900/1150 – 1300
EU Stage V; US Tier 4
Downgrade EU Stage IIIA, IIIB
|Exhaust gas aftertreatment
|DOC/DPF, SCR (Downgrade: tbd)
MAN’s 9-litre diesel engine for off-highway applications put to the test in an agricultural tractor. For this usage, the SCR-only combustion and exhaust gas aftertreatment have been completely revised and adapted. During testing, a large number of field cycles were analysed and the test programme was modified for the tough use in the tractor.MAN Engine D1556 LE5xx