Grandi Motori To Unveil Diesel Engine Designs

—Literature Available Grandi Motori, the diesel engine division of Fincantieri Cantieri Navali Italiani, will be launching a number of new engine designs in the course of this year and 1987. Most of them will be for marine applications or land-based electric power generation.

One unit is the GMT A320 4- stroke, medium-speed engine with outputs from 3,000 to 8,000 bhp at 720-750 rpm, but with special features to insure improved performance at part loads. This type will use the latest bore-cooling technique for combustion chamber components, and utilize to best advantage the greater efficiency of the latest Brown Boveri exhaust-gas turbochargers.

This engine, and the other commercial (non-naval) diesels, are designed for operation on heavy fuel.

Also on extended testbed trials at present is a longer-stroke version of the well-established B550 engine, with a bore of 550 mm the largest of the GMT medium-speed engine range. This new higher-powered, more economic BL550 unit covers a power range from 9,900 to 33,000 bhp for ship propulsion or electric power generation.

With the stroke/bore ratio raised from 1:07 to 1:14 by increasing the piston stroke from 590 to 630 mm, the cylinder output of the BL550 has been increased to 1,650 bhp at 450 rpm with only a modest rise in mean effective pressure from 20.6 to 21.6 bar, and of the mean piston speed from 8.85 to 9.45 meters per second. Modifications to combustion chamber and fuel injection designs, together with adoption of the latest higher-efficiency turbochargers, have already reduced the specific fuel consumption to 178 gr/kW on the standard B550 engine, but it is predicted that the new BL550 will have an even better figure of 168 gr/ kW as a result of higher maximum combustion pressures.

Two of these new type 6-cylinder engines have already been ordered for a ferry for the Italian State Railways, and two others, but with 16 cylinders and as dual-fuel (gas and diesel oil) units for a total-energy municipal power station in Turin.

This longer-stroke BL550 will be available with 6, 8, and 9 cylinders in-line and with from 12 to 20 cylinders in V-form.

Following testbed results on a new 12-cylinder 420H engine, production is about to commence on this new higher-rated version of the GMT A420H (420-mm bore series).

Output per cylinder is increased from 700 bhp at 500 rpm to 800 bhp at 600 rpm. This series now covers an output range from 4,800 to 12,800 bhp, from in-lins with 6, 8, and 9 cylinders, and V-form with 10, 12, 14, and 16 cylinders.

With the Brown Boveri VTR ME4 turbochargers of the latest design and higher efficiency, this class of engine has a lower specific fuel consumption (about 128 grams per bhp-hour) compared with the original A420 engine, a shorter piston stroke of 480 mm, and output per cylinder increased from 700 to 800 bhp at a higher 600 rpm.

As a further development, Grandi Motori is also concentrating efforts on its 230-mm bore, high-speed engine, a highly versatile unit capable of burning heavy fuel oil and therefore suitable for uni-fuel ships. This engine is also available as special M versions for naval ship propulsion and auxiliary applications, including a non-magnetic unit for minehunting naval vessels.

The engine designated B230 is available in two versions, standard and long-stroke, both radically updated as regards cooling arrangements and pressure-charging, and otherwise meeting the higher outputs available from 720 to 1,200 rpm for marine propulsion of commercial vessels, for generating sets, offshore duties, and for naval vessels.

Another major step for Grandi Motori will be taken this year when production is commenced of the supercharged A210SM naval engine, a marked development of the naturally aspirated A210M units installed in the Italian Navy's recent Sauro Class submarines. The latest redesign and other development work has resulted in an even more compact engine with 8, 12, and 16 cylinders in V-form, of low specific weight, and covering outputs of 785, 1,180, and 1,570 kw at 1,500 rpm.

The new A210SM for submarine propulsion has a cylinder bore of 210 mm, piston stroke of 230 mm, and is pressure-charged with intercooling to an MEP of 9.87 bar.

For further information and free literature on GMT engines, Circle 19 on Reader Service Card

Maritime Reporter Magazine, page 20,  May 1986

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