The Cursor 8 and 13 engines
The fact that Iveco did not opt for the Cursor 10 engine, the best-selling model on its road range, may surprise some people. This choice, which reiterates the decision taken in 2000 for the EuroTrakker, was supported by users and is perfectly consistent with the spirit of the two types of use. The Cursor 13 is kept for the most demanding working conditions, where its extraordinary hill starting ability are a guarantee of a long clutch life. There are three power deliveries: 380 Hp, 440 Hp and 480 Hp. The 380 Hp variant is a version with a simple turbocompressor and adjustable turboboost pressure. One of the advantages of the Cursor 8 is its low weight (236 kg less than a Cursor 10) and makes up for its smaller capacity with a very wide field of use and greater gearing down of the transmission. The range includes three power deliveries: 270 Hp, 310 Hp and 352 Hp. The durability of the engine was highlighted in 1997/1998, during the pre-series tests on 44 tonne tractors used by public works companies, and it has been confirmed in the last four years on the EuroTrakker. Generally speaking, all the Cursor engines have undergone long test periods with customers before going on the market, to guarantee immediate reliability on the job.
Tried and tested technology
The technology of the two Cursor engines is identical and it has been proving its worth since 1998 on roads and building sites. Extremely high pressure direct injection is guaranteed by unitary injector pumps activated by a camshaft inside the cylinder block. This camshaft also controls the four valves of each cylinder and in turn is activated by a cascade of gears positioned behind the engine. On the 440 and 480 Hp Cursor 8 and 13, supercharging is provided by a variable geometry turbine, which is optimised to ensure that the engine supplies its best performance at all speeds. On the 380 Hp Cursor 13, supercharging is provided by a simple turbo, which is optimised to provide high torque at low speeds, with a waste-gate valve to adjust the turboboost pressure. The flow of exhaust gas is therefore extremely limited at high speed, to avoid a thermal overload of the cylinder heads and pistons. The action of the vacuum engine brake is reinforced by the turbocompressor. All the engine functions are controlled by the onboard electronics: injection capacity, injection advance, turbine geometry, vacuum brake, speed governor. The control unit that manages it is linked to the other electronic control units that govern the gearbox, the braking system and the retarder on the transmission. Exhaust emissions comply with the Euro 3 Directive. Iveco has succeeded in lowering the level of the polluting substances in question from 28% to 48% with respect to the Euro 2 Directive, without penalising the fuel economy on the vehicles.
Measurements and performance of the Cursor engines
Cursor 8: 6 cylinders in line – diameter: 115 mm – stroke: 125 mm – capacity: 7,790 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: 34.8 Hp/litre
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: 39.7 Hp/litre
Cursor 8-350: Max. power output: 352 Hp (259 kW) from 1930 to 2400 rpm
Peak torque: 130 kgm (1280 Nm) from 1080 to 1930 rpm
Specific power: 45.1 Hp/litre
Cursor 13: 6 cylinders in line – diameter: 135 mm – stroke: 150 mm – capacity: 12,882 cc
Cursor 13-380: Max. power output: 380 Hp (280 kW) from 1500 to 1900 rpm
Peak torque: 184 kgm (1800 Nm) from 900 to 1500 rpm
Specific power: 29.5 Hp/litre
Cursor 13-440: Max. power output: 440 Hp (324 kW) from 1450 to 1900 rpm
Peak torque: 214 kgm (2100 Nm) from 1000 to 1450 rpm
Specific power: 34.1 Hp/litre
Cursor 13-480: Max. power output: 480 Hp (353 kW) from 1530 to 1900 rpm
Peak torque: 224 kgm (2200 Nm) from 1070 to 1530 rpm
Specific power: 37.3 Hp/litre
Cursor engines share three common features that make them particularly suitable for quarry and construction site vehicles:
Their hill-starting capacity. The variable geometry turbocompressor significantly increases torque at low speeds. The Cursor 8 reaches its peak torque of 130 kgm at 1080 rpm, and delivers no less than 101 kgm from 900 rpm. Since the clutch pedal is completely released at this speed, the gearing down of the drive line (a ratio of 1:77 obtained with a ratio in 1st of 1:16.47 and a rear axle ratio of 1:4.67) allows a 32 tonne vehicle to start on a 39% gradient, and a 40 tonne vehicle on a gradient of 30%.
The Cursor 13 obviously boasts superior performance. Its drive line comprises an Ecosplit ZF Overdrive gearbox (1st : 1:13.8 – 16th : 1:0.84 – aperture: 16.47) and a standard rear axle ratio of 1:4.23, with total gearing down of the transmission of 1:58.4. The hill starting capability at 900 rpm is 43% with 40 tonnes and 30% with 56 tonnes for the 380 Hp model; 46% with 40 tonnes and 33% with 56 tonnes for the 440 Hp; 50% with 40 tonnes and 35% with 56 tonnes for the 480 Hp.
The peak torque area extends over a spread of 700 - 850 rpm on the Cursor 8, and over 450 – 600 rpm on the Cursor 13, which guarantees excellent elasticity.
Maximum power is available from intermediate speeds. On rough terrain, the possibility of exploiting the engine with peak torque and power values over a spread of 1400 rpm (Cursor 8) and 900 rpm (Cursor 13), makes gear changes unnecessary on steep slopes.
Summary of the performance of vehicles with the Cursor 8 – 350 engine:
Tyres: 13 R 22.5 – Gearbox ZF 16S151DD – Rear axle ratio: 1:4.67
Theoretical top speed: 105.6 km/h – Speed at 1000 rpm in 1st: 2.67 km/h
Max. gradient negotiable with peak torque at 1080 rpm
with 32 t: 50% - with 40 t: 40%
Max. starting gradient (900 rpm):
with 32 t: 39% - with 40 t: 30%
Summary of the performance of vehicles with the Cursor 13 engine:
Tyres: 13 R 22.5 – Gearbox ZF 16S…OD – Rear axle ratio: 1:4.23
Theoretical top speed: 109 km/h – Speed at 1000 rpm in 1st: 3.52 km/h
Max. gradient negotiable with peak torque at 1000 rpm
Cursor 13-380 with 40 t: 43% - with 56 t: 30%
Cursor 13-440 with 40 t: 50% - with 56 t: 35%
Cursor 13-480 with 40 t: 52% - with 56 t: 37%
Max. starting gradient (900 rpm):
Cursor 13-380 with 40 t: 43% - with 56 t: 30%
Cursor 13-440 with 40 t: 46% - with 56 t: 33%
Cursor 13-480 with 40 t: 50% - with 56 t: 35%
Continuous Power Take-Off
With the timing gear positioned next to the flywheel, the Cursor 8 and 13 offer substantial advantages for public works applications: the possibility of a PTO that is independent of the gearbox, in the rear part of the engine, which can operate a hydraulic pump on a cement mixer when the vehicle is stationary or on the move, or crane pumps when it is stationary. Manufactured by Hydrocar, this PTO has a capacity of 600 Nm on the Cursor 8 and of 800 Nm on the Cursor 13, with a ratio of 1.14:1.
Standard engine retarder
The “vacuum brake” has been an integral part of the Cursor engines since the early days of their development. The principle is simple: the partial re-opening of the exhaust valves at the end of the compression stage, allows the “engine brake” to be increased, effectively exploiting the resistance force. With the addition of a variable geometry turbo, which fills the cylinders with air, the deceleration power of the ITB (Iveco Turbo Brake) on the Cursor 8 reaches 229 kW (310 Hp) at 2800 rpm in continuous mode. On the Cursor 13-440 and 480 Hp it reaches 300 kW (408 Hp) at 2400 rpm in continuous mode (xxx kW at xxxx rpm on the Cursor 13-380 Hp). The vacuum brake, which is adjusted by modifying the turbo geometry, lets the driver control the speed downhill. The vacuum brake technology is superior to that of exhaust brakes, because it does not cause the upper parts of the engine to overheat, since nearly all the hot air is eliminated with the exhaust gases. The efficiency of the retarder depends on the speed the engine is turning at, rather than on the vehicle speed, as in the case of a retarder on the transmission. This feature is particularly useful in construction sites, because the driver only has to change down to increase the engine speed and boost the deceleration power, even if the vehicle is moving slowly.