New from GE Transportation is its L250 Series of six- and eight-cylinder inline marine diesel engines. The 250 mm bore engines offer output ranges from 1500 to 2332 kW, and they were designed with current and future emissions standards in mind.
GE’s medium-speed L250 diesels mark a shift from locomotive heritage
With a rich, nearly 50-year history of building medium-speed diesel engines primarily for locomotives, GE Transportation in Erie, Pennsylvania, U.S.A. has embarked on a change in culture with its first “clean sheet” diesel engine designed specifically for the marine marketplace. The six-and eight-cylinder L250 engines might have been borne from its successful V250 series diesels, but much about the configuration of the new inline engines marks a departure from GE’s locomotive lineage. With tighter emissions standards driving all engine technology, the L250 platform has provided GE the opportunity to design the engines for the marine industry from the start.
“This new L250 engine series completes our green field family of engines designed specifically for marine emissions requirements,” stated John Manison, manager of GE’s marine and stationary power business in Erie. “The V250 engines were launched in 2005 after a five-year development program and, to my knowledge, it’s the first medium-speed engine family launched for the new emissions regulations facing the world. The L250 completes that family. “Since the L250 is based on the V250, we’ve taken much of the V250 design into this engine. So it’s not a completely new engine, but rather we’re working from a proven platform with over 3000 V250s already in service. That’s something that comes up frequently when we talk to our customers about this,” Manison said.
In its six-cylinder configuration, the L250 offers the following continuous outputs:1500 kW at 900 r/min; 1655 kW at 1000 r/min; and 1748 kW at 1050 r/min. In its eight-cylinder configuration, the continuous outputs are: 2000 kW at 900 r/min; 2220 kW at 1000 r/min; and 2332 kW at 1050 r/min. The engines feature a bore x stroke of 250 x 320 mm, a BMEP at maximum rating of 23.3 bar and a compression ratio of 16.8:1. The inline and Vee-configuration 250 series engines offer several improvements over the company’s earlier medium-speed model, the V228.
Chief among these improvements is better fuel efficiency and the capability to meet future emissions requirements, but the L250 engines also offer the ability to mount the turbocharger at either end; a raw water pump; on-engine accessories; and a wider output range. The L250 engines also leverage several component design features from the V250 engines, including camshafts, the fuel system, power assemblies, the exhaust manifold, bearings and the turbocharger.
The inline engines’ mainframe and crankshaft, however, are new designs. Maintaining the same cylinder spacing as the Vee-engine platform provided plenty of design space to optimize the mainframe structural integrity and refine the crankshaft fillet and web geometry, which produces a very high design margin in these new components. Other components specific to the L250 include engine-mounted air and oil filters and an oil cooler, as well as a new fuel pump, high- and low-temperature thermostatic valves and an auxiliary PTO.
“We have developed the L250 engine to cover the same power range as the V228, the 8 and 12 V228,” noted Becky Sidelinger, product manager, marine.“But the L250 was designed specifically for U.S. EPA Tier 2 emissions, with emissions growth capability and it’s optimized at that emissions level for fuel. So we expect the L250 to be somewhere between six and eight percent more fuel efficient than the V228 at Tier 2 emissions levels. “From an emissions growth standpoint,the L250 engine will be upgradeable to Tier 3 without real significant changes, and our customers are expressing a keen interest in that capability,” Sidelinger said.
“For example, we are seeing a lot of interest from ferry providers, with significant interest in repowers. There are ferry companies specifically in the U.S. that are looking to enhance their emissions profile while address rising fuel costs,” she said. “There’s a significant effort under way now to repower a lot of these vessels with more emissions friendly engines that get better fuel consumption and that have that emissions growth capability long term.”GE has also designed these new engines with flexibility and ease of installation and maintenance in mind, in part by allowing the opportunity for operators to specify either end for the mounting of the turbocharger/air intake. While this is not new to the engine industry, is does mark a first for any recently developed engine series.
“It’s all about space on a vessel, that is, flexibility, ease of installation and maintainability,” said John Lynch, manager, application engineering. “There are two driving factors behind our offer of either turbocharger arrangement. One is to make it easier for the vessel builders to install the onboard exhaust system and two, depending on crew location, it is desirable to put the turbocharger as far away from crew quarters as possible. “One of the other focuses of the engine design was to put all of the engine auxiliary equipment on the engine, so the engine tests with all of its accessories and the engine ships with everything mounted,” Lynch said. “This eases the installation requirements for the shipyard or the packager.”
The L250 is also designed with full horsepower PTO capability, another departure from previous medium-speed engine models from GE. “We have seen statistics indicating that as many as 75% of new marine engines will require power takeoff to drive auxiliaries, predominantlyfire-fighting equipment. A PTO on the propulsion engine eliminates the need for an auxiliary engine to drive fire-fighting pumps,” Sidelinger said. Along with the Tier 2 emissions requirements, the L250 engines also will need various classification society approvals, according to Sidelinger. “The 250 has already received the U.S. EPA Tier 2 family certification. And on the marine classification side, we’re working on the ABS certification and we expect that within the next couple of months. The design evaluation is under way now on the L250. Then we’ll pursue other certifications when we have market demand for them.”
GE Transportation’s Grove City, Pennsylvania, engine manufacturing facility is also investing US$4 million to prepare the facility to produce and test the inline engines. The L250s will be built on a new assembly line that will be available starting the end of September. One of the test cells is also undergoing an upgrade to accommodate the new engine.
A schematic of the L250 diesel. The engine was designed specifically for marine applications and its turbocharger can be mounted on either end, adding flexibility for installation.
“The inlines are a major departure from past engines that have been built and tested in Grove City due to their multiple configurations,”explained Yunsu Park, program manager for the L250, based in Grove City. “The need to test engines with both front and rear turbo locations is driving many of the changes. “Having the accessories on the engine during testing is also new and must be accommodated in the test cell,” Park said.“The facility will be capable of testing the L250s starting in November. Development testing on the inlines has been under way since the first quarter of this year — initial start-up of the first engines went smoothly and they have been running very well since.”
Manison added, “The marine engineering team that has been involved in the L250 design has been so excited to take this on. It has been an exciting endeavor for everyone involved. We have many people from all over the engine industry now that work for us both in our engineering and commercial areas and to them this effort has been ‘Why wouldn’t we do this?’”