The driveline: engines and gearboxes
The Cursor engines
Stralis trucks and tractors are powered by the straight six Cursor 8 and Cursor 10 engines. The Cursor 8 has three power outputs: 273 Hp (200 kW), 310 Hp (228 kW) and 350 Hp (259 kW). The Cursor 10 comes in two versions: 400 Hp (294 kW) and 430 Hp (316 kW).
The technology of the two engines is identical and has been tried and tested around the world since 1998. High-pressure direct injection is guaranteed by individual injector-pumps activated by a camshaft inside the cylinder head. This shaft also drives the four valves per cylinder and is activated by the geartrain located behind the engine. Variable Geometry Turbocharging (VGT) technology is utilised to ensure that the engine delivers the best performance at all speeds. The engine brake performance is also increased by the use of VGT. All the engine functions are managed electronically: injection force, injection advance, turbine control, decompression brake, and cruise control. The control unit is linked to the other electronic control units that govern the gearbox, brakes and Intarder on the transmission. Exhaust emissions respect Euro3 standards. Thanks to the excellent work done by the Iveco engineers on the injection system, combustion and electronic management, the relevant pollutant emissions have been reduced (from 28% to 48% compared to the Euro 2 Directive) without detracting from engine efficiency, in other words without raising fuel consumption.
The specific power output of the Cursor 8-350 engine is 45.1 Hp/litre at what might appear a high speed of 2400 rpm. However, the average piston speed does not exceed 10 m/s, which is perfectly acceptable. Used since 1998 on road and since 2000 on heavy construction vehicles in particularly demanding missions, the Cursor 8 has spearheaded the design qualities of the new generation of Iveco engines.
On the Stralis Active Time/Active Day, the surface areas of the coolant radiator and heat exchanger of the turbocharger air (intercooler) have been increased. The fan operates for shorter periods, thus absorbing less power. The turbocharged air that reaches the engine is cooler, with benefits for the engine operating temperature and pollutant emissions. Fan activation is guaranteed by an electromagnetic coupling, governed by the on-board electronic system. Unlike viscostatic couplings, there is no residual resistance outside operating phases.
Measurements and performance of the Cursor engines
Cursor 8: 6 cylinders in line; bore: 115 mm – stroke: 125 mm – capacity: 7790 cc
Cursor 8-270: Max. Power output: 270 Hp (200 kW) from 1720 to 2400 rpm
Peak torque: 114 kgm (1115 Nm) from 1000 to 1720 rpm
Specific power output: 34.8 Hp/litre
Homologated for 5 Ecopoints
Cursor 8-310: Max. Power output: 310 Hp (228 kW) from 1950 to 2400 rpm
Peak torque: 114 kgm (1115 Nm) from 1100 to 1950 rpm
Specific power output: 39.7 Hp/litre
Homologated for 5 Ecopoints
Cursor 8-350: Max. Power output: 350 Hp (259 kW) from 1930 to 2400 rpm
Peak torque: 130 kgm (1280 Nm) from 1080 to 1930 rpm
Specific power output: 45.1 Hp/litre
Homologated for 5 Ecopoints
Cursor 10: 6 cylinders in line; bore: 125 mm – stroke: 140 mm – capacity: 10308 cc
Cursor 10-400: Max. Power output: 400 Hp (294 kW) from 1480 to 2100 rpm
Peak torque: 194 kgm (1900 Nm) from 1050 to 1480 rpm
Specific power output: 38.7 Hp/litre
Homologated for 5 Ecopoints
Cursor 10-430: Max. Power output: 430 Hp (316 kW) from 1590 to 2100 rpm
Peak torque: 194 kgm (1900 Nm) from 1050 to 1590 rpm
Specific power output: 41.7 Hp/litre
Homologated for 5 Ecopoints
Engines homologated for 4 Ecopoints are also available
The Cursor engines boast three common features that make them particularly economical to drive:
Peak torque is available from low engine revs (between 1000 and 1100 rpm) which simplify starts with full loads.
The area of peak torque extends from 700 to 850 rpm on the Cursor 8, and from 400 to 500 rpm on the Cursor 10, which provides great engine flexibility with reduced gear changes.
The maximum power output is reached at intermediate speeds, which means that the engine revs do not always have to be kept high to the detriment of fuel economy. The Cursor 10-430 delivers its maximum power at 1590 rpm. The area of constant power delivery extends for 500 – 600 rpm and can used on difficult gradients, for example, to avoid too many gear changes.
The Iveco Turbo Brake: continuous decelerating power of 380 HP
All the Cursor engines are equipped with a "turbocharged" decompression brake: partial re-opening of the exhaust valves after compression makes it possible to increase the "engine brake", exploiting the resistant force better. By boosting the variable geometry turbocharger, which fills the cylinders with air, the continuous deceleration power of the ITB (Iveco Turbo Brake) reaches 229 kW (310 Hp) at 2800 rpm on the Cursor 8 and 280 kW (380 Hp) at 2400 rpm on the Cursor 10. ITB performance is comparable with that of an Intarder on the transmission. The decompression brake, which can be adjusted by modifying the turbine geometry, enables the driver to adjust the speed downhill. Decompression brake technology is superior to that of a conventional exhaust brake because it does not cause the upper parts of the engine to heat up. Another advantage is the fact that much of the heat produced by the ITB as it absorbs energy is dispersed with the exhaust gases, without overloading the engine cooling system, which thus remains available for an Intarder on the transmission.
The gearboxes
Trucks powered by the Cursor 8-270 and 8-310 engines are fitted with the ZF Ecomid 9S 109 gearbox which has 9 synchronised ratios. The other engines are available with ZF Ecosplit gearboxes with 16 synchronised ratios: the 16S 151 for the Cursor 8-350 and the 16S 181 for the Cursor 10-400 and 10-430. To simplify engagement of the 8 main ratios, the control incorporates ServoShift assistance. Intermediate ratios are pre-selected using a pushbutton under the gear lever knob and engaged simply by depressing the clutch pedal. The gate of the 8 main ratios is of the "double H" type. This simple layout is immediately comprehensible even to a driver using an Iveco Stralis for the first time.
An automated gearbox
All versions of the Stralis Active Time and Active Day can be fitted with the EuroTronic II 12Active Space 2301 12-ratio automated gearbox. This concept, developed by ZF and Iveco, has been used since 1997 on the EuroTronic I and since 2000 on the EuroTronic II. The gearbox is without friction synchronisers. The gear speed is balanced by the electronic adjustment of the engine speed. The clutch function, which is also controlled electronically, guarantees very smooth operation, even on hill starts with a full load. As a result, the clutch pedal has been eliminated. With EuroTronic II, the driver can choose between semi or fully automatic operation. In semi-automatic mode, he makes gear changes by use of the sequential gearlever. In fully automatic mode, the software is programmed to change gear based on the position of the accelerator pedal, the resistant torque on the propeller shaft, the engine speed and the available engine torque.
In fully automatic mode, the EuroTronic II transforms any driver into an expert in economical driving. Because it is very simple to use, it is easy to learn and its operating logic – which exploits the power and torque characteristics of the Cursor engines – has proved ideal on all types of road; motorways on level ground, the twists and turns of main roads or congested urban areas. The EuroTronic II also enhances safety because it reduces driver fatigue and helps the driver to maintain concentration until the end of the shift. Experience has shown that electronic control of the clutch when starting protects the clutch friction plate, extending its life. And finally, a further advantage for hauliers wishing to increase their payload: the EuroTronic II weighs 65 kg less than the 16 S 181 gearbox with the same capacity, and 49 kg less than the 16 S 151 gearbox, without counting the fact that the mechanical levers have been eliminated.
