Highest power density in its class, innovative charging concept for peak power and an optimal torque and power profile.
The MAN D4276 with its bore of 142 mm and stroke of 170 mm sets a new benchmark by delivering an impressive 581 kW from 16.2 litres of displacement with the highest power rating: Weighing no more than 1,280 kg, this power pack is not only the most powerful in-line 6-cylinder engine for agricultural and construction machinery ever developed by MAN Engines, but also has the highest power density in its displacement class. This peak output has been achieved by MAN Engines as a result of its newly developed charging concept with fixed-geometry charger, which enables a maximum torque of 3,400 Nm between 1,350 rpm and 1,600 rpm. Thanks to its unique performance characteristics, the D4276 helps OEM manufacturers to set them and their machines apart from the competition. To comply with current emission standards, the D4276 relies on the compact, flexible and modular exhaust gas aftertreatment (AGN) system from MAN Engines and will be available for the main markets in models meeting EU Stage V and EPA/CARB Tier 4.
The design of the MAN D4276 is based on the modern MAN D3876 engine series, which has already been successfully established on the market, but has been systematically developed to meet the increased performance demands of heavy-duty applications in agricultural and construction machinery. To achieve this, it was necessary to further improve the already outstanding power density of the MAN D3876. This meant expanding the bore by four millimetres from 138 mm to 142 mm, thereby increasing the displacement from 15.3 to 16.2 litres. A modification of the Common Rail injection system provides the necessary increase in fuel supply. The use of a fully redeveloped high-pressure pump generates supply quantities up to 40 per cent higher while vibration loads and noise emissions remain constant. Diesel injectors that have been further developed especially for the MAN D4276 with improved flow rate and high injection pressures of up to 2,500 bar ensure an ideal degree of fuel atomisation and penetration. This results in low-emission, low-soot combustion combined with more favourable levels of fuel and AdBlue© fluid consumption.
To obtain maximum power of 581 kW, MAN Engines has developed a charging concept with a high power output in the upper engine speed ranges. Due to the required power characteristics, a fixed-geometry charger is used in the process. As a result, the 6-cylinder engine offers a maximum torque of 3,400 Nm between 1,350 rpm and 1,600 rpm – which is sufficient power for instance for large combine harvesters and forage harvesters, but also for large excavators, shredders and mining vehicles. During the thermodynamic design process, the engineers at MAN Engines came up with a turbine geometry that has its optimum efficiency level specifically in the main operating range of the off-road machines. In addition to this, the turbine geometry was designed to prevent the cylinders from interfering with each other during the charge cycle, thereby achieving good response characteristics and an optimum air throughput across all engine speed ranges. A turbine housing made from heat-resistant cast steel and a compressor housing made from aluminium that can withstand high temperatures further increase the turbocharger’s robustness and create thermal reserves, for example for use in high altitudes.
The base power unit and a large number of additional components and parts were adopted from the award-winning MAN D3876 engine series without modification. As a result, the MAN D4276 has retained virtually the same compact installation dimensions (1,464 x 978 x 1,131 mm length/width/height) as the “Diesel of the Year 2016”, despite offering more power. As the interfaces of the two engine series are also virtually identical, customers require only a single installation variant to allow both the MAN D3876 and the MAN D4276 to be integrated without major design changes. In addition, concepts that have already been successfully tried and tested in the MAN D3876 make a reappearance, such as the “domed valves”, which use a convex-shaped reinforcement of the valve plates on the combustion chamber side to minimise seat wear, thereby enabling the valve clearance to be checked at less frequent intervals. Another concept used is top-down cooling, where the coolant is distributed along the engine via the upper water jacket of the cylinder head, thereby ensuring an equally high cooling output across all cylinders. Modifications have also been made to the crankcase and pistons to further optimise the MAN D4276’s cooling system. As the MAN D3876’s lightweight construction concept has also been adopted, the MAN D4276’s dry weight of 1,280 kg makes it only slightly heavier than its little brother and also means that it has by far the highest power density in the 16-litre class. Thanks to the standard parts concept, customers can also rely on fully-developed, tried and tested parts from large-scale production which, in the case of the MAN D3876, have been used in MAN’s own commercial vehicles on the road since 2014 and in off-road applications since 2016. This not only ensures high quality parts, but also guarantees ease of service and repair work as well as optimum spare parts logistics across all MAN engine series.
Differing requirements for compliance with the emission legislation depending on the application and target market mean that flexible and individual solutions are required for exhaust gas aftertreatment. MAN Engines offers its modular exhaust gas aftertreatment system (AGN) for this purpose, with a broad selection of interchangeable components that can be combined with great versatility. The AGN system essentially consists of the two DOC/DPF modules (diesel oxidation catalytic converter / diesel particulate filter), coupled with an SCR (selective catalytic reduction) system. Due to the engine’s low-emission combustion design, an SCR system is all that the MAN D4276 requires to comply with EU Stage V and EPA/CARB Tier 4. The new engine also relies on an exhaust gas recirculation system with water cooling. DOC/DPF are not required, which saves additional space and money. In order to meet the special requirement and performance profile of the MAN D4276, the SCR catalytic converter used has a vanadium coating that can withstand high temperatures. This provides greater stability and helps maintain the engine’s performance in extreme situations such as heat and altitude.
The MAN D4276 is also available in a variant with up to 515 kW. MAN Engines has already presented this model at bauma in Munich in April 2019. The model was designed especially for machines with a large torque and power requirement in the lower engine speed range. A turbocharger with variable turbine geometry (VTG), which is already tried and tested in off-road applications, is used to retain maximum power and torque across a broad engine speed range. The turbocharger provides high charge-air pressure reserves for torques of up to 3,250 Nm at rotational speeds of 950 rpm to 1,500 rpm. The broad torque plateau of the MAN D4276 not only delivers highly dynamic response characteristics in partial-load and full-load operation, but also always facilitates the required excess air for low-particle and consumption-optimised engine operation. Here too, the modular AGN system from MAN Engines ensures compliance with EU Stage V and EPA/CARB Tier 4 emissions standards. Solutions are also available for countries with less stringent regulations.