Marking a first in the Indian automotive landscape, Tata Motors recently launched eight new models across five platforms on the same day. At the same occasion, the company also unveiled a new corporate strategy HORIZONEXT, which has been explained in detail in our Shopfloor section in this issue. All these vehicles are essentially facelifts or upgrades. Of these eight vehicles, the three most important ones include the new Indigo eCS, Sumo Gold and the Nano. Completing the line-up are CNG versions of the Indigo eCS, Indica and the Nano along with a Safari Explorer and petrol Indica.
On the sidelines of the event we spoke to Dr Timothy Leverton, Head – Advanced and Product Engineering, Tata Motors Ltd. He gave us an insight into the technical changes done to some of the vehicles in the 2013 line-up.
The new Indigo eCS and Indica features revised exteriors and interiors, but the main change comes in the form of an updated powertrain. The new CR4 engine is now equipped with F-Shift gearbox, which is claimed to offer smoother and easier shifts. Another key update in the car is the Duo Float suspension, which Leverton said, is a dual path strut suspension and will offer improved ride quality.
He told us that in a conventional set-up all the struts and springs react into one bush at the top, which requires for an optimisation of bush settings for both the spring and damper. In the new suspension, engineers have separated the load paths of the spring itself from the damper. This means the compliances for both can be better optimised, allowing for a reduction of up to one-third in ride vibrations at the seat over a conventional suspension.
Tata claims an improvement in NVH models across all its 2013 model range and Leverton told us that this has been achieved by creating a noise package spread across various areas of the vehicle. The company created a package, which covers parts such as beadings, insulation and many others, all of which lower the in-cabin sound levels. This also includes changes related to resonance within the exhaust system at a detailed level, and not fundamental. Although we weren’t given a figure for the improvement in NVH, Leverton called the improvement “quite noticeable”.
Talking about changes in fuel efficiency, he said that Tata Motors already has a strong position in this area and has concentrated on improving the drivability and in-cabin experience in the new models. The new Sumo Gold, however, features an improvement of about 4 % in fuel-efficiency along with an improvement in drivability. The improvement has been achieved by looking at areas such as gearing, frictional losses in the system and more.
CNG models do offer high fuel efficiency from a cheaper fuel but mostly at the expense of boot space. With the Nano already being a small car, using the boot space to store the CNG tank/cylinder would render it almost useless. Understanding the same, engineers designed the CNG system for the Nano in such as way that space usability isn’t affected. The CNG cylinder instead of being mounted in the space behind the seats has been integrated in the centre of the car. This set-up provides consumers with all monetary benefits of using CNG without giving up anything on space. Such an arrangement is not a global first, but to achieve it on one of the world’s smallest and tightly packaged cars is quite an achievement in our opinion.
At the launch, we were told that the 2013 Nano features a new steering system among many other inclusions and is claimed to be the lightest to operate among manual steering equipped cars. Explaining the changes, Leverton said the team looked at all possible improvable elements in the steering system. These meant changes to the joints & rack design and reducing friction in order to reduce the operating effort. The tyres and suspension geometry were also looked into along with caster angles but the details of these weren’t disclosed. In addition, the steering wheel itself has been enlarged slightly and as a combination of all these changes, the steering is claimed to be significantly lighter than the earlier model.
Text: Arpit Mahendra