words - Andrew Norton
When you think of gameboat power, you generally don't think of Iveco, reports Andrew Norton

Established in 1975, Iveco is one of the world's largest diesel manufacturers and has built 15 million engines, four million of which are still in service. The company builds more than 460,000 diesels annually, making it a larger company than Volvo and some other European manufacturers.

Yet among the brands of marine diesels commonly thought of, Iveco rarely rates a mention. Most boat owners know of Cat, Cummins, Volvo and Yanmar in the mid-range horsepower classes and MAN and MTU for superyachts , but mention Iveco and they shrug their shoulders. Perhaps it's because Iveco has been overshadowed by its parent company, Fiat, which has been an engineering company for around a century.

And that's a shame, because Iveco makes an entire range of diesels featuring plenty of torque down low for getting a heavily-laden hull onto the plane, full electronic engine management for precise fuel control, low fuel consumption and exhaust emissions, and ease of engine installation.

Currently Iveco's recreational marine diesel range comprises models from 12kW (16.1hp at 1.0hp = 746 watts) to 882kW (1182). Models such as the Series 4000 are built in association with Lombardini Marine (well known for its air-cooled industrial diesels) and the others by Iveco itself.

The relatively high-revving Lombardini motors (12-60kW) are available with either conventional gearboxes or saildrives (up to 55kW) while the slower-revving Iveco models start at 59kW.

All Lombardini and Iveco recreational diesels have freshwater (heat exchanger) cooling and, sensibly, the motors are either naturally aspirated or turbo-charged and aftercooled, avoiding the inefficiencies of straight turbo-charged diesels.

Iveco's electronically-managed NEF 370 is one such engine and is the most powerful of a range of common-rail diesels in three, four and straight-six cylinder configurations. Available also in commercial and even industrial output ratings, the NEF 370 is part of Iveco's "New Engine Family" which is basically one litre per cylinder.

Features of the entire range include assembly on a sophisticated production line complete with continuous monitoring systems implementing 3D gauging machines, which according to Iveco provides new standards in precision machining of parts such as cylinder bores to reduce fuel and lubricating oil consumption.

All engines have relatively simple OHV layouts with gear-driven camshafts and an aft timing gear train to reduce noise and torsional effects. Large cooling water passages are fitted for optimal thermal stabilisation and the sump is fully suspended to reduce noise emissions.

Iveco has created a new cylinder head where the injector is mounted vertically in the centre of the combustion chamber for even air/fuel swirl, while the common-rail injection system, which Fiat claims it invented, allows for injection pressures of up to 1600bar via the electronically controlled injectors. Mounted on the side of the engine block for easy access or replacement, the engine management computer continuously monitors each cylinder to compensate for component wear. All engine running information is stored in memory and may be accessed via a laptop computer when servicing.

Iveco says that when rated down to commercial and industrial specs, valve clearance checks are needed only after 4000hr of operation, while oil and diesel fuel filter change intervals are 500-800hr. The company also says that the extremely "clean" combustion process reduces oil deterioration by half, hence the long service intervals.

Under the Pleasure Boat or A rating the 5.9lt NEF 370 can be compared directly with Yanmar's 5.8lt 324kW (434hp) 6LY2-STE despite the fact it develops 272kW (365hp).

One reason is that the NEF 370 develops maximum power at 2800 revs compared to 3300 for the Yanmar. And unlike the Yanmar which is Pleasure Duty rated for only 200hr of operation per year (Yanmar doesn't supply the Wide Open Throttle [WOT] percentage of running time in that rating) the NEF 370 is rated at 10 per cent WOT operation in any one hour with a duty cycle of 300hr per year.

But the main reason is that although the NEF 370 produces 1050 Newton metres (Nm) of torque compared to 1100 for the Yanmar, it does this at 700 fewer revs.

As I've mentioned before in Trade-A-Boat, maximum engine power is irrelevant in all but high performance sportsboats. More important is torque and excellent throttle responsiveness across a broad rev range - and that's where the NEF 370 really scores.

Whereas the Yanmar has the fairly "peaky" torque curve common to most mechanically-injected diesels, the NEF 370's curve has a straight rise from 1000-1800 revs. For example, at 1000rpm it produces 400Nm, rising to 590 at 1200, 750 at 1400 and 900Nm at 1600rpm. The motor is still producing 1020Nm at 2200rpm and 880 at WOT. In comparison, the Yanmar produces 800Nm at 1700rpm, 1100 at 2500 and 900Nm at WOT.

The rapid rise in torque enables the NEF 370 to handle most planing power applications without needing a two-speed gearbox, whereas my testing of the Yanmar in two very different hulls (and also from US test results) shows the engine really benefits from the extra gear ratio.

With its electronic engine management, the NEF 370 has a lower specific fuel consumption than the Yanmar, only 205gm per kW/hr compared to 269 for the Yanmar. Unfortunately Iveco doesn't supply propeller power curves, so actual fuel consumption at any given revs cannot be accurately calculated.

Of course all engines have drawbacks, and the NEF 370 has a bobtail (minus gearbox) weight of 595kg compared to 515kg for the Yanmar. The NEF 370 is also bulkier, measuring 1310mm long, 805mm wide and 790mm high, compared to 1275 x 708 x 709mm for the Yanmar.

As with the MAN 450 reviewed recently in Trade-A-Boat, I must confess that for planing hull applications I would choose an electronically-managed diesel every time over a mechanically-injected unit. The rapid torque rise from low revs, flat torque curves, excellent fuel efficiency, relative ease of complying with ever-stricter exhaust emission regulations and the straightforward installation really make these engines stand out from their mechanical counterparts.

For more information, contact Stewart Butler at Lees Industries Group, tel (07) 3390 5522.

Published : Friday, 1 August 2003

Prices and specifications supplied are for the market in Australia only and were correct at time of first publication. boatsales.com.au makes no warranty as to the accuracy of specifications or prices. Please check with manufacturer or local dealer for current pricing and specifications.