Nannidiesel 4.200 TD

Based on a Kubota industrial/tractor diesel, the 4.200 TD slots neatly into Nannidiesel's existing lineup of marine diesels, which now ranges from 10 to 320hp.

Base engines for the range are supplied by Kubota, MAN, and Toyota.

In Australia the Nannidiesel range is distributed by Sydney-based Collins Marine, which handles engines up to 155hp, although more powerful engines are in the pipeline.

The four-cylinder 4.200 TD develops 59.2hp (based on 1.0hp equaling 746W) at 2800rpm from its 1999cc four-cylinder powerhead. The cylinder bore is 83mm, the piston stroke 92.4mm.

Indirect injection is used to meet EU and US EPA exhaust emission regulations for diesel engines. Nannidiesel says the 4.200 TD emission levels are well within the European CE 94/25 anti-pollution standards, which have a more stringent gas emission level than the European 94-25 EEC standard.

To meet this compliance without resorting to electronic engine management, Kubota uses its 'E-TVCS' three vortex combustion system, where the injector is positioned centrally in the cylinder head surrounding the intake and exhaust valves.

Unusually for a diesel in this power range the 4.200 TD is straight-turbocharged, yet it still has a high 22:1 compression ratio more commonly found in naturally aspirated indirect injection diesels.

Straight turbocharging has its pros and cons. Advantages are a more thorough air/fuel burn resulting in more power and torque from a given piston displacement.

Disadvantages are higher intake air temperatures, which can reduce engine lifespan when operating in tropical climates, whereas intercooled engines have denser air intake again but cooler temperatures. And if your yacht has a waterlock exhaust raiser to prevent backflooding, it will have be modified to allow for the increased exhaust gas flow (turbocharged engines hate excessive back pressure) when re-powering from a naturally aspirated engine.

Finally, the additional boost pressure of the turbocharger can lead to cylinder head stress around the pre-combustion chamber outlet, resulting in cracking here.

However, this is relatively uncommon and compared to direct competition such as Volvo Penta's D2-55, the 4.200 TD scores with its impressive torque output at low revs, exactly what yachties need to survive in the confines of capital city marinas!

COMPARISON
Both the four-cylinder indirect injection 4.200 TD and D2-55 have pushrod OHV designs for reliability but differ in that the 2.2lt D2-55 is naturally aspirated.

The 4.200 TD develops maximum power at 2800rpm, whereas the D2-55 develops 55hp at 3000rpm.

But while the D2-55 has a peak torque output of 135Nm at 2350rpm, the 4.200 TD produces 169Nm at only 1800rpm. Even at 1400rpm it produces 165Nm, and at 2800 revs the output is 155Nm.

Unfortunately, Nannidiesel doesn't supply fuel flow figures for the 4.200 TD so at this stage it's not possible to compare the engines directly.

However, at cruising revs of 2600, where the prop is absorbing 34hp, the D2-55 uses 8lt/h and, as the 4.200 TD can absorb 36.8hp at these revs, it should use about 8.5lt/h, based on turbocharged engines being more fuel efficient at all but wide open throttle.

At 3000rpm, the D2-55 uses 12.5lt/h and the 4.200 TD should consume about 14lt/h at 2800rpm.

Complete with a mechanical TMC260 2:1 gearbox, the 4.200 TD has a dry weight of 248kg, only 5.0kg heavier than the similarly-equipped D2-55.

Nannidiesel uses either ZF or Technodrive (twin disc) gearboxes and, complete with box, the 4.200 TD is 931mm long, 505mm wide, and 632mm high.

With a mechanical MS2A box, the D2-55 is 917 x 544 x 691mm, so apart from additional length the 4.200 TD is significantly more compact.This is quiet an achievement considering the 4.200 TD also has turbocharging.

As standard the D2-55 has a 12V alternator, which produces up to 60 amps at 14V for battery charging, while the 4.200 TD's 12V alternator produces 100 amps at 14V.

Both engines have heat exchanger cooling with the freshwater circulating pump driven by the alternator belt and the sea waterpump driven by the camshaft.

COMPONENT LAYOUT
Although the main Nannidiesel brochure for this engine is written in French, I was able to analyse the engine component layout (I'm glad I had a French girlfriend all those years ago).

The alternator is mounted high up on the engine just below the level of the freshwater header tank but, oddly for an inboard nowadays (in view of potential litigation), there's no shroud for the drive belt or pulleys.

The oil sump vacuating pump is located at the forward end of the engine along with the canister oil filter.

Beneath the turbocharger and air compressor is a sump oil cooler with a large capacity; essential to maintain relatively low oil temperature for both the engine and turbocharger.

Directly ahead of the oil cooler is the water-separating fuel filter, which in my opinion should be closer to the inline fuel injector pump, mounted well forward on the starboard side.

At least the fuel lines are routed atop the air intake manifold and the injectors located between the manifold and rocker cover are easy to access and replace.

At the same height as the header tank the compact turbocharger has a dry element air filter close-coupled to the air intake compressor.

Midway forward on the starboard side is the easily-accessible seawater cooling pump, along with the fuel pump driven by the camshaft.

On the portside is the starter motor mounted well above engine bearer level. To reduce exhaust back pressure, the 4.200 TD needs a minimum 60mm exhaust outlet diameter.

The maximum static installation angle is 15 degrees.

For more details on the 4.200 TD (including the saildrive model), contact Peter Collins at peter@collinsmarine.com.au, or by phoning (02) 9319 5222.