Opel’s hot Mokka
The Mokka sub-compact SUV has proven to be a hit for Opel. In October 2014, the company reported that in the two years since being brought to market, the sub-compact SUV had been ordered 300,000 times, with the latest 100,000 orders recorded in the prior seven months.
The Mokka is the third most sold car in the Opel rankings behind Corsa and Astra but ahead of Insignia and Zafira.

The Mokka 1.6 CDTI accelerates from zero to 100 km/h in 9.9 seconds, and makes the transition from 80 to 120 km/h in fifth gear in just 9.9 seconds. Maximum speed is 191 km/h (119 mph). With Opel’s six-speed manual transmission and standard Start/Stop system, the 1.6 CDTI Mokka consumes 4.1 l/100 km (57 mpg US) over the combined cycle while emitting only 109 g/km CO₂. This is almost 0.5 l/100 km less fuel and 11 g/km less CO₂ than the predecessor 1.7 liter version.

The two-liter turbo diesel in the Insignia has a specific output of 87 hp per liter—a slightly higher power density than Opel’s new-generation 1.6 CDTI. Torque of 400 N·m is available from 1,750 to 2,500 rpm, and maximum power of 125 kW/170 hp is accessed at just 3,750 rpm.

The new powerhouse delivers around 4% more power and 14% more torque while maintaining exactly the same consumption as it predecessor and meeting Euro 6 emission standards. The Insignia with the new engine reaches a maximum speed of 225 km/h (140 mph): an increase of 5 km/h. The sedan accelerates from 0 to 100 km/h in just 9.0 seconds – almost half a second quicker than its predecessor.

Two of the main contributors to the performance of both engines are the VGT (variable geometry turbine) turbocharger and the high-pressure, common-rail fuel injection system.

• The VGT in the Insignia features an electrical actuator for the variable aspect turbine, giving a 20% faster boost response than a vacuum actuator.

• Injectors capable of supplying fuel at 2,000 bar and of up to 10 injection pulses per cylinder cycle ensure high power, improved fuel atomization and efficient mixing with the air intake charge.

The 1.6 CDTI in the Mokka uses a Lean NO_x Trap (LNT), an exhaust after-treatment system upstream of the diesel particulate filter that captures and removes nitrogen oxides (NO_x) from the exhaust gases without the use of additives.

2.0 CDTI with 125 kW/170 hp for Opel Insignia. Click to enlarge.

The Insignia comes with Opel’s BlueInjection selective catalytic reduction (SCR) system, which removes nitrogen oxide from the engine’s exhaust gases. Tiny quantities of AdBlue, a fluid consisting of urea and water, are injected into the exhaust gas flow ahead of the SCR catalyst and downstream of the Diesel Particulate Filter (DPF). The solution is immediately converted into ammonia (NH₃), which is absorbed by the SCR catalyst. Nitrogen oxide in the passing exhaust gas is then selectively reduced to nitrogen and water vapor in a chemical reaction with the ammonia.

Apart from increasing performance and efficiency, the improvement of running smoothness was a key requirement for the new engines right from the outset of their design. The engineers implemented several measures during construction and fine-tuning to reduce the noise levels and vibrations of the engine thus improving refinement. Architectural improvements focused on two main noise-emitting areas: the top and bottom of the engine and ranged from a decoupled, cam cover on the aluminum cylinder head over a newly designed oil sump to a new balancer shaft module for the two-liter diesel.

The new 2.0 CDTI thus features reduced noise levels in every rpm range compared to its predecessor and is five decibels quieter when idling.