Brake in power 28 August 2014

Fiat Powertrain Technologies' latest Cursor 16 engine offers monster power and torque, but it probably won't be appearing in an Iveco truck anytime soon. Brian Weatherly reports

Fiat Powertrain Technologies' (the division of CNH Industrial that provides engines for family member Iveco) recent launch of the 15.9-litre Cursor 16 captures the conundrum facing Europe's truck makers with ultra-high power, large-displacement diesel engines. Namely, can the considerable investment in time and money to engineer them into a heavy truck be recouped by the limited number likely to be sold in a niche-market?

Just how niche can be seen by the average horsepower rating of UK 44-tonne tractors. That remains firmly fixed at around 450bhp, with registrations of units at more than 510bhp accounting for no more than 5%. It's also worth pointing out that, aside from Volvo and Scania, no other European truck maker offers more than 650bhp in a top weight truck. Plainly, only the Swedes see a demand.

By any yardstick, Cursor 16 is a muscular motor, capable of delivering up to 857bhp and 3,500Nm of torque – although, for the moment, it's only available for construction, power generation and agricultural applications. Even so, the new beast has already chalked up its first 'world's most powerful' accolade – for the latest 625bhp New Holland Agriculture CR10.90 combine harvester. And note: selling across multiple markets clearly helps defray the development costs of such large-displacement diesels.

So when might we see Cursor 16 powering an Iveco Stralis or Trakker? The short answer from the Italian manufacturer is: "There are no plans to roll it out into production trucks." Is that the end of the story? You can seldom say 'never' in truck manufacturing and, as Cursor 16 has been invested with several interesting features – not least its ability to meet both Stage IV/Tier 4 (construction) and Euro 6 emissions regulations – it's well worth some examination.

Like its smaller Cursor stable mates, the Euro 6 Cursor 16 was co-developed by FPT Industrial's R&D teams in Arbon, Switzerland, and Turin in Italy. Like them, it will also be built at its Bourbon Lancy plant in France. So it's no surprise that, like the smaller Cursor 13, Cursor 16 clears the Euro 6 fence using SCR (selective catalytic reduction) – unlike the vast majority of Euro 6 truck engines, which use a mix of SCR and EGR (exhaust gas recirculation). FPT says its patented HI-eSCR (high efficiency selective catalytic reduction) system reduces NOx emissions by more than 95%.
"HI-eSCR increases reliability and lowers maintenance costs, while reducing operating costs over the entire product lifecycle," says a spokesperson. "The compact system also allows for the optimisation of space and minimises the weight impact, due to integrated components." Maintenance intervals are currently quoted at 600 hours.

Measuring 1,378 x 1,010 x 1,326mm for the most powerful version, Cursor 16 has almost the same dimensions as the 12.9-litre Cursor 13 (Cursor 16 is slightly taller) and is just 60kg heavier, with the same air-handling system, too. Bore and stroke is 141 x 170mm. Those figures prompt FPT to declare that it delivers "18-litre performance in a 13-litre package".

Cursor 16 also comes with either single- or dual-stage turbocharger arrangements, depending on output. Single turbo versions are available from 653—775bhp, with torque from 2,990 to 3,320Nm. The twin-turbo model offers whopping maximum outputs of 707—857bhp and up to 3,500Nm torque. According to FPT, the new engine has "improved performance and durability, designed to deliver performance for heavy-load applications, with the second-stage [turbo] version offering a fuel economy advantage in high load factor operations".

On dual-stage turbocharger versions, the turbos operate sequentially (there is no bypass), with the smaller unit providing low rpm responsiveness, while the second, larger, turbine delivers maximum boost at high rpm. On its single-turbocharger Cursor 16 engines, FPT installs a smaller, fixed-geometry turbocharger to help overcome turbo lag. However, to avoid turbo over-speed a waste gate lets a proportion of the exhaust gases bypass the turbocharger once maximum pressure is reached. For the first time, FPT is also using ball bearings for its turbochargers, allowing the engine manufacturer to claim reduced tolerances, so "improving the performance of turbochargers at low speeds".

Cursor 16 is the first FPT Industrial engine to come with a CGI (compact graphite iron) cylinder head and liners, which the firm says increases thermal and mechanical resistance – and again reduces engineering tolerances, so improving efficiency. Like MAN's D38 (Transport Engineer, August 2014, page 20), Cursor 16 also has steel pistons (previous Euro 5 Cursor engines used alloy), which are less prone to thermal expansion. Yet again, the benefit is tighter tolerances and hence higher peak pressures, resulting in higher power density and also a claimed reduction in particulate emissions.

Additionally, the piston crowns feature FPT's in-house developed double re-entrant combustion bowl, which creates two separate vortices within the bowl. These are claimed to ensure accurate control of the fuel-air mix, in turn maximising performance and minimising emissions, while ensuring no residual fuel left on the cylinder-linings.

As with its smaller Cursor siblings, the four valves per cylinder Cursor 16 has a so-called third-generation common rail fuelling system, operating at up to 2,200 bar. The common rail reservoir and pipework are also all enclosed within the rocker cover. Consequently, the new engine looks very clean externally. A rear gear train timing system has also been adopted to reduce engine noise and vibration.

Notwithstanding Cursor 16's clearly impressive credentials, it does beg the question: Does Iveco really need it? Based on likely sales volumes, the answer is probably not, especially as the most powerful Cursor 13 engine in Stralis Hi-Way already provides up to 560bhp. Further, ensuring sufficient cooling for a 600bhp-plus Cursor 16 beneath a Stralis cab would require additional engineering time (and money) from the Italian truck maker that might be more profitably spent elsewhere. And then there's the not insignificant matter of creating a drivetrain to match it.

Ironically, there is one Iveco model that might provide a home for Cursor 16 – its bonneted PowerStar 7800 tractor, locally designed and built in Australia for road train operations carrying up to 140 tonnes gtw. While PowerStar already has Cursor 13 as an option, for any opertor wanting more than 560bhp, Iveco relies on Cummins' 15-litre ISX/Signature. Running at those down-under gross weights, large-displacement diesels like Cursor 16 begin to make more sense.

Meanwhile, despite all the ballyhoo over power, it's worth mentioning that having a maximum rating of 'just' 510bhp for its 13-litre MX engine since Euro 5 hasn't significantly impacted on DAF's heavy truck sales volumes. And, as Europe's manufacturers increasingly push the concept of 'down-sized' 11-litre diesels for their heavies, the demand for 'big' engines with ultra-high-horsepower (apart from dedicated heavy-hauliers and power-hungry owner-drivers) is set to remain small.

Author
Brian Weatherly

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