Engine and transmission: Efficient power pack

May 5, 2018
Affalterbach

In the new G 500 (fuel consumption, combined: 12.1-11.5 l/100 km; combined CO2 emissions: 276-263 g/km)1 a high-performance 4.0-litre V8 petrol engine ensures powerful propulsion. The new biturbo delivers an output of 310 kW (422 hp) and a maximum torque of 610 Nm at 2000 to 4750 rpm. Further power units are already planned.

Efficiency and effortless power delivery were the top priorities for the new 4.0-litre V8. One factor in this is the special NANOSLIDE® coating on the cylinder walls. This ensures less friction, which helps to improve efficiency and also reduces wear. The biturbo has a cylinder shutoff function to reduce fuel consumption even further. In the partial load range, the variable valve control system CAMTRONIC deactivates four cylinders at the same time. This reduces the gas cycle losses while improving the overall efficiency of the remaining four cylinders by shifting the operating point towards higher loads. Cylinder shutoff is active in the engine speed range from 800 to 3250 rpm in the Comfort and ECO driving modes. When torque increases, cylinders 2, 3, 5 and 8 are unnoticeably reactivated within milliseconds. The G 500 is also equipped with a petrol particulate filter.

Hot inside V

For even better engine responsiveness, the cylinder heads of the V8 biturbo are rotated by 180 degrees: the intake side is on the outside, the exhaust side on the inside, which makes the V8 biturbo particularly compact. Specialists refer to this concept as a "hot inside V".

Key data of the G 500 at a glance:

 

G 500

Displacement

3982 cc

Bore x stroke

83.0 x 92.0 mm

Compression ratio

10.5:1

Output

310 kW (422 hp) at 5250-5500 rpm

Peak torque

610 Nm at 2000-4750 rpm

Fuel consumption, NEDC combined 1

12.1-11.5 l/100 km

CO2 emissions 1

276-263 g/km

Efficiency class

E

Acceleration 0-100 km/h

5.9

Top speed

210 km/h

New automatic transmission on board

For the transfer of power, the 9G‑TRONIC automatic transmission with torque converter was specifically adapted to meet the needs of the off-road icon. The developers have managed to reduce the shift and response times of the 9-speed transmission by means of a dedicated software application. The wide transmission ratio not only makes driving quieter and more comfortable especially at low engine speeds, it simultaneously also contributes to reducing fuel consumption.

Further improved mechanical components and the hydraulic control unit ensure fast, gentle and comfortable gear shifts, and allow brisk intermediate sprints. In addition, three rpm sensors allow so-called nested gear changes, where several gears are skipped depending on the driving situation. The shift characteristics vary according to the selected drive program.

In ECO mode, the ECO start/stop function helps to ensure particularly economy-minded driving. The gliding function also helps to save fuel. When the driver's foot leaves the accelerator pedal, the transmission's clutch disengages. This reduces the engine speed to idling level, and the driving resistance is reduced by the compression and frictional forces of the engine on the overrun. The G-Class "glides", using its own, current kinetic energy for a certain distance. It rolls for a measurably longer distance than when on the overrun. This results in further fuel savings. The clutch is re-engaged as soon as the driver operates the accelerator or brake pedal. As is usual with Mercedes-Benz automatic transmissions, the driver is able to change the gears manually. This is made possible by the DIRECT SELECT shift paddles at the steering wheel.

Transfer case with low-range ratio

The new transfer case is flange-mounted directly on to the 9G-TRONIC. It is configured so that 40 percent of the drive torque reaches the front axle and 60 percent reaches the rear axle. This configuration particularly benefits the handling characteristics on the road. At the same time the permanent all-wheel drive ensures maximum traction. However, the "G" would not be a "G" if it did not have even more in store. The low-range ratio considerably increases torque at the drive wheels, which e.g. makes very difficult terrain negotiable.

The low-range ratio can be engaged via the LOW RANGE switch in transmission mode N at speeds of up to 40 km/h. The gear ratio of the transfer case is then changed from 1.00 in HIGH RANGE to 2.93. It is possible to switch from LOW RANGE to HIGH RANGE at speeds of up to 70 km/h. The gear ratio of the transfer case is 2.93 and thus significantly shorter than in the predecessor model (2.1), which becomes noticeable particularly when pulling away on an extreme gradient.

The new, intelligent multiplate clutch behaves like an automatically controlled locking differential. It ensures that the G-Class remains manoeuvrable for longer. The advantage is that the driver has more scope before having to engage the differential locks manually. This means that the multiplate clutch controls the behaviour of the "G" when driving, e.g. in case of slip on or off the road. When the switch for the centre differential lock is operated, the multiplate clutch switches to a 100% fixed locking effect. The locks at the front and rear axle differentials are normal differential locks with a 100% locking effect. All the locks can be engaged individually while on the move, both in LOW RANGE and in HIGH RANGE, in the sequence centre, rear axle and finally front axle differential. The differential locks now respond to the switches even more rapidly, as they are purely electromechanically actuated and fully networked. An LED and the central driver's display indicate which lock is currently active.

1 The stated figures were determined in accordance with the prescribed measuring method. These are the "NEDC CO2 figures" according to Art. 2 No. 1 Implementing Regulation (EU) 2017/1153. The fuel consumption figures were calculated based on these figures.

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