Iveco diesel, the Cursor 500

Last month Engine Talk reviewed the Iveco NEF 370, an alternative diesel to Yanmar's popular 440 unit. But although smaller Iveco units have been appearing in hulls such as the Black Watch 34, gameboat owners may not know about the larger units.

The Cursor 500 is a specific engine within several different engine families, which range from 12kW (16.1hp @ 1.0hp = 746W) to 882kW (1182) in the recreational line-up and 42kW (56.3) to 625kW (838) in commercial ratings.

But as Iveco decreases its engine families from six to four by utilising more modularity of components (such as the New Engine Family of one-litre-per-cylinder) it will expand its engine output to 1765kW (2366) to compete with MTU, which currently is the most popular choice for megayacht power.

The four engine families are the F1 with two four-cylinder engines to 162kW (217), the NEF already covered, the straight six Cursor range and the New V Family from 6 to 16 cylinders (currently up to 12 cylinders).

Iveco also has a global target of reducing exhaust gas emissions by up to 50 per cent and fuel consumption by 10 per cent, by developing its electronic engine management systems further. Currently the electronic common-rail engines comply with IMO Marpol 73-78 and the European directive EC 94-25 for emission levels.

The company wants to reduce engine weight by 20 per cent and overall engine bulk by 30 per cent, while increasing engine life cycles by 30 per cent and decreasing maintenance requirements by 50 per cent, which it already has achieved in the commercially-rated version of the NEF 370.

THE CURSOR 500
Suitable for gameboats in the 12-13m range (such as the Black Watch 40) the 7.8lt turbo-intercooled Cursor 500 is rated at 368kW (493) at 2600rpm, compared to 2900 for 368kW 7.4lt mechanically-controlled Yanmar 6CXM-GTE2 diesel. The Cursor's "pleasure duty" rating is 10 per cent of Wide Open Throttle (WOT) operation in any one period, with an annual duty cycle of 300 hours, whereas Yanmar does not readily supply this information.

Yanmar says the specific full-load fuel consumption of its engine is 234 grams per kilowatt/hour, compared to 203 for the Cursor 500 - excellent for an engine of this output.

As with its NEF 370 counterpart, the Cursor 500 develops plenty of power from low revs: 175kW at 1400rpm, 240 at 1600, 280 at 1800, 310 at 2000, 340 at 2200 and 360 at 2400. At the same sets of revs the Yanmar develops 150, 210, 270, 310, 345 and 355kW respectively, while at 2600rpm it's developing 360kW, so in the upper rev range there's little difference.

But as with the NEF 370 compared to Yanmar's 440, the torque curve is substantially different. At 1400rpm the Cursor 500 produces 1200Nm, and by 1600rpm the figure is 1450Nm with a maximum torque of 1520Nm between 1800 and 2000rpm. Even at 2600rpm the output is 1350Nm.

In comparison, the Yanmar produces 1080Nm at 1400rpm, 1280 at 1600, 1410 at 1800 and 1490 at 2000 with a maximum torque of 1500Nm at 2100rpm. From 2200rpm the output steadily declines to 1200Nm at 2900rpm.

The lesser torque output at lower revs is surprising, considering that at 110 x 130mm for the bore and stroke (compared to 115 x 125 for the Cursor 500) the Yanmar has substantially greater undersquare design.

However, mechanically-controlled diesels have fixed injection timing, where the timing is too advanced below, and too retarded above, the maximum efficiency zone (usually where the greatest amount of torque is produced), whereas the electronic management system of the Cursor 500 provides optimum timing across the entire rev range.

A DIFFERENT APPROACH
But whereas the Yanmar weighs 825kg in bobtail form (minus gearbox) the Cursor 500 weighs 910kg. And the Yanmar measures 1504mm long, 876mm wide and 905mm high compared to 1671 x 956 x 943 for the Cursor 500, which is obviously a substantially bulkier engine.

Unusually the Cursor 500 also has a less powerful starter motor - 4.5kW compared to 4.8kW. Although whereas the Yanmar has a 12V, 55amp alternator, Iveco has opted for a 24V, 90amp unit that charges at 28V and recommends using two 120amp/h batteries for starting.

Iveco has designed the Cursor 500 to have very good installation flexibility and allows a continuous front up/front down running angle of 16° and a surprisingly high port or starboard angle of 22°. The heat exchanger cooling system has a fresh water cooled exhaust manifold and turbocharger for more consistent temperature control and better component longevity, while the aircleaner is an oiled unit and not dry.

The Cursor 500 is fitted with electronic engine management that constantly monitors factors such as ambient, coolant and exhaust temperatures and engine loads to provide an accurately measured fuel spray for each cylinder, and compensates for wear as the engine accumulates running hours.

The information is stored in a memory which is then downloaded to a laptop computer during servicing, providing technicians with complete details of load, revs and how the engine has been treated by owners. This should ensure that boatbuilders don't overprop the engine, which is a common complaint from the diesel manufacturers I've interviewed.

The electronic engine management system is easily accessed from one side of the motor and enables throttle and gearshift control wires to be easily connected instead of having to rely on control cables, which can create annoying vibrations.

The Cursor 500 is available with a choice of gearboxes including the ZF280A, ZF304A and Twin Disc TDMG5075A. These boxes increase the overall engine weight to 1018, 1088 and 1067kg respectively.

For more information on the Cursor 500, contact Stewart Butler at Lees Industries Group, tel (07) 3390 5522 or email: leesinda-sales@powerup.com.au.