MAN Diesel & Turbo has announced the introduction of its L35/44DF engine, the latest addition to its four-stroke portfolio. Spurred on by developments in environmental legislation and the strict emission limits resulting from that, the new engine offers dual diesel fuel-gas running and can also be introduced as a retrofit to engines already in service. The first prototype entered its test phase at the beginning of 2012’s second quarter at MAN’s Augsburg facility. A V-type engine version is being developed simultaneously that will enlarge the power-output range of the company’s dual-fuel engine portfolio as part of MAN Diesel & Turbo’s market strategy.

According to MAN, it is introducing the L35/44DF engine at a time where separate emissions legislation for harbors is set to come into play, in addition to the upcoming IMO Tier III emission regulations for marine applications. Accordingly, MAN said it views the introduction of another engine that offers the option of operation on gaseous fuels as timely, also in the context of ship owners’ increasing environmental awareness. With the L35/44DF engine, the company is continuing the expansion of its product program with a dual-fuel engine based on common rail technology.

MAN’s development objective with the new engine was to produce a high efficiency/ high specific power output unit that complied with IMO Tier II emission limits in diesel mode and IMO Tier III limits in gas operation. A high degree of fuel flexibility (HFO, MDO, MGO and natural gas) was another primary objective. With an output of 530kW/cylinder, the inline 35/44DF is available in 6 – 10 cylinder configurations, equivalent to total power outputs from 3.2 MW to 5.3 MW. This represents the highest power output available in the segment and complements that offered by the larger L51/60DF type.

The L35/44 engine has also been specifically developed for the retrofit of 32/44CR-T2 engines where it can avail of a high level of component synergies and the same crankcase, which can be re-machined on board. Subsequent engine operation is mainly intended for gas mode with a separate pilot ignition system – based on proven technology widely employed by the truck industry – that is independent of the primary, common rail injection system. However, the common rail system is retained and fully functional as a back-up system in the event of any problem while operating in gas mode.