MAN power

Released late last year, MAN's D 0836 LE 401 electronically managed straight six diesel slots in neatly between the Yanmar 5.8lt 324kW (at 3300rpm) 6LY2A-STP and 7.4lt 368kW (2900) 6CX-GTE2 diesels for weight and torque output. And though slightly down on power, it compares favourably with Volvo's 7.3lt 353kW (at 2600rpm) 74P EDC engine on a power-to-weight and torque-to-weight basis.

MAN is marketing its 450in twin installations at the 10.7 - 13.7m cruiser range, but it would ideally suit gameboats such as the Black Watch 36 or 40. It develops 331kW (444hp at 1.0hp equals 746W) at only 2600rpm, the same as the Volvo, from its 6.87lt piston displacement. The bore and stroke are 108 and 125mm and the compression ratio 15:1, low even for a turbo-intercooled diesel.

MASSIVE TORQUE, EXCELLENT FUEL EFFICIENCY
Like its V12 1500 counterpart, where this MAN diesel scores over the direct competition is the massive torque at relatively low revs, assisted by utilising a watercooled exhaust system with internal insulation to conduct uncooled exhaust gas to the turbocharger via an "inliner". This improves turbocharger boost pressure and reduces exhaust emissions.

The 450 produces a maximum torque output of 1325 Newton metres at 1700rpm. Based on my testing of a Black Watch 36 with twin Yanmar 324kW engines, which produce maximum power at 700 more revs and planed this hull at 2800rpm, it's safe to assume MAN 450s would achieve this at 2000-2100rpm, where they would be producing 1300Nm.

And in a Black Watch 40, twin 368kW Yanmars achieved a clean plane at 2200rpm (where they produced 1480Nm) and reached 3000rpm at Wide Open Throttle.

The torque rise from 1000rpm is only matched by the electronically managed Volvo. At 1000rpm the MAN 450 produces 670Nm; at 1100rpm, 800Nm; and at 1200rpm, 950Nm. Even at 1400rpm, 1300Nm of torque is produced, while at Wide Open Throttle the output is 1220Nm.

In comparison, the mechanically injected diesels from Yanmar have "peaky" torque curves. The 324kW engine develops 1100Nm at 2500rpm but only 800Nm at 1700rpm. By the time 2800rpm has been reached, the torque is down to 1060Nm, dropping to 900Nm at 3300rpm.

The 368kW engine has a similar torque curve. Although it produces 1500Nm at 2100rpm, at 1400rpm the output is 1100Nm and at 1700rpm 1320Nm. By the time 2900rpm has been reached, the torque has dropped to 1200Nm.

The electronic engine management ensures excellent fuel efficiency for a diesel of the 450's output. Based on a standard propeller power curve, at 1000rpm the prop is absorbing 30kW (40.2hp) and the fuel consumption is 8lt/h, while at 1100rpm and 38kW (50.9) it's 10.3lt/h. At 1200rpm the prop absorbs 50kW (67.0) and the motor consumes 13.4lt/h, and at 1400rpm the figures are 70kW (93.8) and 18.3lt/h.

At 1700rpm the prop absorbs 120kW (160.9) and the consumption is 30lt/h. On the plane at 2000–2100rpm - right at this motor's lowest specific fuel consumption where the prop is absorbing 175kW (234.6) to 190kW (254.7) -the usage is 42.3–46.0lt/h. The WOT consumption is 82.7lt/h. Compared to the 324kW Yanmars in the Black Watch 36, which were consuming 50.0lt/h each and 90.0lt/h at WOT, the 450's fuel consumption is excellent.

Planing at 2200rpm, the 368kW Yanmars in the Black Watch 40 consumed 41lt/h each, and 105lt/h at WOT.

Having tested the 324kW Yanmar with both single and two-speed ZF gearboxes, I believe the latter suits the peaky torque curve of this engine much better. But the flat torque curve of the MAN 450 allows it to be mated with a single-speed box without significant performance loss. According to Seapower Australia's CEO, Bernard Stojkovich, the most popular gearbox choices have been ZF and Twin Disc, and interest in the ZF 2-Speed has been virtually non-existent.

LIGHT, COMPACT, SENSIBLE ENGINEERING, LOGICAL ELECTRONICS
In bobtail form (minus gearbox) the 450 weighs 730kg, compared to 515kg for the 324kW Yanmar, 825kg for the 368kW Yanmar and 860kg for the Volvo.

To reduce overall size, the 450's heat exchanger and gearbox oil cooler are integrated with the expansion tank. The 450 measures 1330mm long, 860mm wide and only 830mm high, compared to 1274 x 708 x 709 and 1504 x 876 x 905 for the two Yanmars respectively, while the Volvo is 1142 x 794 x 937.

To reduce servicing time and costs, the cylinder heads are grouped together in twos and items such as the fuel pump and oil filter are accessed from one side. MAN also rates its 450 at 2600rpm with an ability to maintain this speed for one hour in five, whereas Volvo rates its 2600rpm at one hour in every 12. The MAN duty cycle is based on 1000 hours of operation per year, whereas the Volvo is 800hr and the 324kW Yanmar only 200hr.

The 450 has electronic fuel injection for minimal (if any) exhaust smoke and effective engine control under widely varying load conditions. The MAN Monitoring and Diagnostic System (MMDS) records engine revs and operating hours, engine oil pressure and temperature, engine coolant temperature, gearbox oil pressure and temperature, turbocharger boost pressure and charge-air temperature.

If a status critical for the engine is reached, an alarm is triggered and the engine output reduced by 25%. Alarm reports are stored in the MMDS and can be accessed via a laptop computer, resulting in more effective fault diagnosis and reduced maintenance time down the track.

The MAN 450 adds a welcome choice to existing motors in this power range and provides a brilliant blend of power, torque and fuel efficiency in a compact, low-weight package that should suit the needs of gamefishers who demand instant throttle response and plenty of torque to quickly plane their boats.

For more information, contact Seapower Australia on (08) 9335 9777 or email man@seapower.com.au.