Turbochargers propel future of A-segment

25th July 2014

By: Donna Slater

Features Deputy Editor and Chief Photographer

  

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The continual development and enhancement of turbochargers installed on small-capacity engines are set to become the future staple for A-segment or entry-level vehicles, reports German vehicle manufacturer Volkswagen South Africa (VWSA).

VWSA product engineering head Jan Schiedek-Jacht tells Engineering News that turbochargers are proving increasingly popular in the A-segment, owing to their ability to almost double the amount of air during the combustion process of internal combustion engines. “Turbos can double the torque and power of an engine,” he says, adding that this enables VW to build powerful, highly efficient, yet lightweight and small engines that use less fuel, compared with naturally aspirated engines.

Schiedek-Jacht notes that small-capacity engines in the range of 1 ℓ to 1.2 ℓ are the most ideally suited to be fitted with a turbocharger, taking into account the compromise between fuel consumption, takeoff performance and power output.

The use of forced-air induction from turbo- chargers in small-capacity car engines is a relatively new concept; however, Schiedek- Jacht notes that “nearly all other original- equipment manufacturers are planning on incorporating small turbocharged petrol engines in their compact-car segment”.

New Polo
The VW Polo range is one of the world’s best- selling compact models, with nearly 14-million units sold worldwide to date, according to VWSA.

The VW factory, in Uitenhage, is one of the two plants in the brand’s production network that assembles the Polo hatchback and, in South Africa, the Polo is produced for local and export markets.

VW states that, since the original Polo hatchback’s launch in 2010, it has consistently been the second-best-selling passenger car in South Africa. In 2013, the Polo hatchback recorded sales of 23 501 units. The bestselling car in South Africa since 2010 is the Polo Vivo, which was also launched in the same year.

The new Polo hatchback’s fuel economy has been improved by as much as 20% with the addition of a turbocharger and reduced engine capacity.

The new Polo hatchback was launched onto the South African market in June with a new powertrain in the form of two versions of VW’s four-cylinder 1.2 ℓ turbocharged engine that produces 66 kW and 81 kW.

The two new 1.2 ℓ turbo stratified injection engines replace the previous engine offering of the 1.4 ℓ and 1.6 ℓ normally aspirated engines, which produced 63 kW and 77 kW respectively.

The 66 kW derivative delivers maximum power at 4 800 rpm while turbocharging boosts the torque at this power level to 160 Nm between 1 400 rpm and 3 500 rpm. This engine also achieves an average fuel consumption of 4.9 ℓ/100 km. A top speed of 184 km/h is possible and acceleration from standstill to 100 km/h can be achieved in 10.8 seconds. This engine is also available with a five-speed gearbox.

The 81 kW derivative delivers maximum power at 5 000 rpm and its maximum torque of 175 Nm is delivered between 1 500 rpm and 4 000 rpm. This engine achieves an average fuel consumption of 5.1 ℓ/100 km, with a top speed of 196 km/h and acceleration from standstill to 100 km/h in 9.3 seconds.

As an alternative to the standard six-speed transmission, the 81 kW derivative is also avail- able in an optional seven-speed direct shift gearbox (DSG), which enhances efficiency, dynamics and comfort. Fuel consumption with the DSG remains unchanged at 5.1 ℓ/100 km.

Driver Assistance
The new Polo hatchback offers driver assistance systems such as the automatic postcollision braking system and the driver alert system.

The automatic postcollision braking system automatically initiates braking to avoid secondary collisions or reduce the severity of a secondary collision. The system is triggered when a primary collision is detected, ensuring controlled handling of the car by the driver, even in the case of automatic braking.

The driver can override the automatic postcollision braking system at any time, with the system being deactivated if it senses pressure on the accelerator pedal or if the driver initiates hard braking with greater deceleration than the system deceleration.

The driver alert system is standard in the Highline models of the new Polo. This system detects waning concentration of the driver by monitoring the driver’s behaviour. It emits an acoustic warning for the duration of five seconds and displays a message in the instrument cluster recommending that the driver take a break from driving. If the driver does not take a break within the following 15 minutes the warning is repeated.

Edited by Megan van Wyngaardt
Creamer Media Contributing Editor Online

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