Page 44: of Maritime Reporter Magazine (July 15, 1986)

PROPULSIONUPDATE

Grctndi Motori Already Has Orders

For Its New Long-Stroke

Medium-Speed Diesel —Literature Available—

Now undergoing prolonged test- ing in the Trieste factory of the

Grandi Motori division of Fincan- tieri Cantieri Navali Italiani is a new long-stroke, higher-powered, me- dium-speed 4-stroke engine cover- ing a power range from 9,900 to 33,000 bhp. With a cylinder output of 1,650 bhp at up to 450 rpm, this

BL550 diesel is one of the world's highest-powered, medium-speed en- gines for ship propulsion or land- based electric power generation.

Rigorous testbed trials are con- tinuing, and GMT director M. Car- chidio says that the results are more than confirming predictions.

Orders have already been received for four of these newly developed

BL550 engines—two 6-cylinder units for a ferry ordered in Italy by the Italian State Railways, and two dual-fuel (gas and diesel oil) Vee- type units for a total-energy plant for Turin. The engines for the ferry are scheduled for testbed trials in

October this year.

The BL550 is a further develop- ment of the GMT 550-mm bore, 4- stroke engines put on the marine and industrial markets in 1970.

Compared with the original A550, the new BL550 has the piston stroke increased from 590 to 630 mm, rpm from 435 to 450, MEP from 17.6 to 21.6 bar, and output per cylinder from 1,200 to 1,650 bhp.

As with all Grandi Motori low- and medium-speed engines, the

BL550 is designed and equipped to burn heavy fuel oil. Over the past 10 years research and development ef- forts have been concentrated on re- ducing further the specific fuel con- sumption and improving reliability, with extended operating periods be- tween the need for maintenance or overhaul.

The new engine retains the prov- en characteristics of the B550 ver- sion. The increased stroke/bore ra- tio, from 1.07 to 1.15, has enabled the compression ratio to be raised without excess shallowing of the combustion chamber, which have otherwise reduced the volume for effective fuel atomization, but the present design has reduced fuel con- sumption to 130 grams per bhp hour. However, as a result of a high- er maximum combustion pressure and increased compression ratio,

GMT's design team confidently pre- dicts a lower value of 124 g/bhp-hr.

Lower fuel consumption and ex- haust valve temperatures are the result of an improved pulse-pres- sure-charging system using the latest turboblowers of greater effi- ciency, together with readjusted timing for the inlet and exhaust valves.

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