MAN base engine: The basis for our engines

Independently of the aforementioned, tests to check the overall engine system of each application are mandatory. The result is an engine with a 90 ° bank angle, a displacement of 2 l per cylinder with 128 mm bore and 157 mm stroke, a bottom-mounted camshaft and four valves per cylinder.

For high variability in the number of cylinders, the engine is equipped with single cylinder heads. In order to meet the exhaust emission standards of various applications and to achieve high injection pressures, a common rail injection system was chosen.

Due to the high gas forces occurring at high loads, the crankshaft is not bolted to the main bearings with individual bearing covers, but – unusual for this engine size – via a crankcase bottom section (the so-called bedplate). Due to the high rigidity of the bedplate and the optimised bolting against the crankcase, secure bearing of the crankshaft is guaranteed even at the highest loads.

When designing the base engine, the specific requirements of the respective application were taken into account.

This also applies to on-road vehicles. In classic tractors, for example, the installation space is very tight since they are often equipped with more compact 6-cylinder engines.

In addition to the wide torque range and powerful acceleration, a low engine weight is a decisive design criterion, as it is directly reflected in an increased payload.

In railway engines, high thermal shock loads can occur. These result from the typical operation of regional trains: Starting the train at the station with strong acceleration, rolling, braking when reaching the next station – all that in constant repetition.

In the agricultural machinery sector, the engine must feature an increasing torque characteristic to be able to drive into the harvested or shredded material at overspeed and have sufficient torque available at the start of processing when the speed drops.

Engines for power generation are used either as continuous power generators (COP: Continuous Power), for peak load coverage (PRP: Prime Power) or as an emergency generator (LTP: Limited Time Running Power and ESP: Emergency Standby Power).

Depending on the operating mode, the power and the permissible annual operating time differ as follows: 50 hours p.a. for emergency generators, unlimited up to 24 hours per day for continuous generators.

Gensets usually consist of the engine with a pre-installed combination radiator for charge air and coolant cooling and a flange-mounted alternator.

All engines for power generation are operated at constant speed: 1,800 rpm ^{for 60 Hz, 1,500 rpm for 50 Hz AC voltage. When operating with a flanged alternator, further loads occur on the engine. The generator shaft is supported on the crankshaft, which must be taken into account in the crankshaft design and the torsional vibration calculation.}

In addition, due to the frequency control of the entire genset, fluctuations in the power grid can be passed on to the motor as torque surges. The place of use must also be taken into account. Engines are sometimes used with little protection in dusty environments such as the desert, or at high geodetic altitudes of up to 4,000 m with low air oxygen content.

In addition to diesel operation, the engine is also designed for operation with natural gas and biogas. This engine is available with outputs from 270 kW to 580 kW. A separate cylinder head, piston and cylinder liner were developed for operation with gas. The remaining engine parts are identical to those of the diesel engine. By comparison: Diesel units as V12 engines have outputs of 700 to 1,117 kW.

Marine engines are characterised by the special installation situation on ships. For example, marine engines are cooled with seawater. Cooling is initially provided directly by the charge air, then via a plate-type heat exchanger using engine coolant.

In addition, elaborate measures are necessary to comply with the applicable legal regulations on ships. The “International Convention for the Safety of Life at Sea (SOLAS)” requires, among other things, a maximum surface temperature of 220 °C for the engine.

For this purpose, a water-cooled exhaust system was installed, in which the high-temperature-resistant exhaust gas-carrying components (exhaust pipe, turbocharger) are insulated via an air gap by water-cooled, double-walled aluminium shells. For use on workboats, further regulations of so-called classification societies, such as the Germanische Lloyd, apply. Workboats can often only be operated or even insured after acceptance by one of these companies.

The aim is always the safety of passengers and crew on board. For example, engines must be equipped with redundant sensors and double-walled injection lines. Avoiding the use of hoses and certain materials, such as aluminium in the fuel area, where possible is intended to increase fire resistance.

Engines in marine applications are also subjected to very different loads. Use on yachts is characterised by the demand for very high performance and acceleration values, albeit with low annual running times. For the highest performance levels, the engine is equipped with two-stage turbocharging with intercooler (two turbochargers per bank).

In the workboat sector, on the other hand, robust engines with long running times at lower outputs are required. Typical workboats are e.g. pushboats and barges, passenger ferries, pilot boats, fishing cutters, excursion boats, and patrol boats. All these boats are equipped with at least twin engine systems (two engines per vessel).

Often, individual requirements of the applications appear contradictory during the design. For example, durability at high power levels (and the associated high gas forces) conflicts with the demand for the lowest possible weight in low-power engines. In order to still be able to use common parts sensibly, a large number of significant components were optimised. For example, the bedplate design has resulted in a robust and very rigid construction, which also has advantages for low-power engines.

In various areas, however, common parts were deliberately omitted. In order to be able to reasonably reproduce the various application-specific torque curves and power outputs, pistons with different grinding patterns and different compression as well as adapted valves are used.

This means that, in addition to mainly software variations in injection and turbocharger design, the efficiency of the individual engines can be significantly increased.

For different delivery rates, different gear widths are used on both the oil pump and the coolant pump.

• Road use: Compact installation space since smaller 6-cylinder engines are normally used, higher engine weight means lower load capacity

• Railway: Low overall height, e.g. due to underfloor installation or roof installation, high temperature change loads due to the train approaching the station with strong acceleration, rolling, braking when reaching the next station
• Agricultural machinery: Tight installation spaces, use in very dusty environments, increasing torque characteristics for power compensation when driving into the crop, high vibration loads due to non-elastic engine mounts

• Standby gensets: Annual operating time 50 hours per year with overload.
• Continuous generators: 24/7 Load on the engine due to flange-mounted alternator, environmental loads due to surroundings (e.g. desert, mountains)

• Workboats: Robustness with long running times at lower outputs, narrow installation space, cooling with seawater, safety regulations for operation and insurance by classification societies, such as Germanische Lloyd (redundant sensors, double-walled injection pipes, fire-resistant materials)
• Yachts: Very high performance with high acceleration values but low annual running times