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First 6-cylinder RT-flex50

August 25, 2005

Successful tests for six-cylinder RTflex 50 diesels

The first two of the latest Sulzer RT-flex50 common-rail marine engine type developed by Wartsila Corporation, have successfully completed official shop tests and class type approval tests at licensee Diesel United Ltd in Japan.

With five to eight cylinders, the Sulzer RT-flex50 low-speed marine diesel engine covers a power range of 5,800 to 13,280 kW at 99 to 124 rpm. It is thus well suited to the propulsion of bulk carriers in the Handymax to Panamax size range, product tankers and feeder container vessels.

The Sulzer RT-flex50 is based on the Sulzer RTA50 engine jointly developed by Wartsila and Mitsubishi Heavy Industries Ltd in Japan.

Instead of the camshaft-controlled systems of the RTA50, the RT-flex50 uses electronically-controlled common-rail technology for fuel injection and valve actuation.

The new technology provides great flexibility in engine setting, bringing benefits in lower fuel consumption, lower minimum running speeds, smokeless operation at all running speeds, and better control of other exhaust emissions.

The Sulzer RT-flex50 engine is designed to meet market needs for outstanding reliability, high efficiency, compactness, optimised industrialisation, and environmental requirements. As with all new marine engines these days, it is fully compliant with the NOx emission regulation of Annex VI of the MARPOL 1973/78 convention.

Two six-cylinder engines were involved in the tests at Diesel United's works in Aioi, Japan, each with a contracted maximum continuous power of 9,720 kW at 124 rpm.

The first engine completed its official shop tests on July 21, 2005 after a comprehensive program of testing as is usual for a new engine design.

The second engine completed its official shop test on August 13, 2005. In the presence of representatives from the principal classification societies, it also successfully passed the type approval tests for Sulzer RT-flex50 engines and for the WECS-9520 electronic control system which is now incorporated in Sulzer RT-flex engines.

The first 6-cylinder Sulzer RT-flex50 engine is for export to Korea for a 37,000dwt product tanker under construction at Hyundai Mipo Dockyard Co Ltd (HMD).

The second 6-cylinder RT-flex50 engine will be delivered to Shanghai Edwards Shipbuilding Co Ltd in China for installation in a 19,625 dwt cargo vessel.

The Sulzer RT-flex50 has been well received by shipowners.There are already 28 of the engines on order for newbuildings contracted with shipyards in China and South Korea for a variety of owners in China, Greece, Scandinavia, India and the Netherlands. Two of these engines have seven cylinders, while the remaining 26 units are six-cylinder engines. The newbuildings they will power are 20,000 to 53,800 dwt bulk carriers and 37,000 to 52,000 dwt product tankers and LPG carriers.

The RT-flex50 is the latest Sulzer low-speed marine engine type to incorporate RT-flex common-rail technology. A total of 205 RT-flex engines have been ordered, aggregating some 8.9 million kW. These include all Sulzer RT-flex engine types, from 500 to 960 mm cylinder bore, with individual engine powers up to 80,080 kW. The first RT-flex engine entered service in September 2001 and has accumulated some 21,000 running hours.

Principal characteristics of Sulzer RT-flex50 marine diesel engines

Cylinder bore: 500 mm

Piston stroke: 2050 mm

Stroke/bore ratio: 4.1

Power, R1 MCR: 1,660 kW/cylinder, 2,260 bhp/cylinder

Speed range, R1R3: 12499 rev/min

Numbers of cylinders: 5 to 8

Power range: 5,80013,280 kW, 790018,080 bhp

BSFC at full-load R1 rating: 171 g/kWh, 126 g/bhph


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