M43 Engine

A fourth series of new generation long-stroke engines, the M43, was introduced by MaK in 1998, effectively replacing the 450 mm bore M552C model and exploiting the same design philosophy as that of the M20, 25 and 32 series. With a specific rating of 900 kW/cylinder at 500/514 rev/min, the initial in-line six, seven, eight and nine-cylinder models covered an output range up to 8100 kW. The power band was extended in 2002 with the launch of V12, 16 and 18-cylinder (VM 43) models taking the upper output of the series to 16 200 kW (Figure 21.9).

Figure 21.9 A V12-cylinder version of the 430 mm bore M43 design (The VM43)

Eighty per cent component commonality is shared by the in-line and vee-cylinder designs, and simplicity of assembly was sought by combining as many functions as possible into single structural elements, thus reducing the overall number of components in the engine. Common components and component groups are: the complete cylinder head; valve drive; cylinder liner with flame ring; exhaust gas system (without compensator); camshaft bearings; fuel injection pump; high pressure connection; injection nozzles; cooling water distributor housing and line (without insertion tube); connecting rod and bearings; and vibration damper.

Cylinder head: a proven double-ended nodular cast iron design ensuring a high level of shape retention, the four-valve head is held on the cylinder liner by six hydraulically tightened studs (all the bolts are tightened simultaneously). Simple dismantling and assembly is fostered by insertion tube connections for all the media. The two exhaust valves are arranged to rotate, and the valve seating rings and ducts are aerodynamically optimized.

Piston: the two-part component comprises a steel crown and steel skirt. The crown is equipped with two compression rings and an oil stripper ring; the first ring is chromium plated on the flanks. The oil-cooled shaker space of the piston ensures effective cooling at a high mean effective pressure and contributes to a long piston life.

Connecting rod: the split-shaft design allows low piston installation/ withdrawal heights. The rod bolts and shaft bolts are tightened hydraulically. (The size and weight of the hydraulic tools used for tightening bolts on the engine are minimized by operating with 2500 bar pressure technology.)

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