Technology ’s TDI engines scalable, efficient platform

Recent generations have progressively brought about changes to diesel as a fuel, making it efficient, smooth and a powerful technology. An ardent supporter and developer of diesel technologies is German carmaker, Audi. Having introduced the Turbocharged Direct Injection (TDI) engine in 1989, the company has sold more than five million cars with TDI engines. As the globe continues to shift towards diesel, we take a look at Audi’s future-ready technology.

INTRODUCTION contribute significantly to overall volumes sions without sacrificing power. Depend- by 2020. Presently, the country is the fast- ing on the vehicle, the configuration of Audi is presently pursuing a challenging est growing market for Audi globally. Of various engines may vary but majority of target of becoming the world’s largest pre- the achieved growth, most of it was the architecture and working principle mium carmaker by 2020. We say the tar- driven by sale of diesel vehicles. More remains the same. A key feature of all TDI get is ambitious, because that not only specifically, it’s the TDI technology driv- engines is the power output, which in means Audi will have to surpass BMW ing Audi’s growth in India. We drove the most cases is among the best in its class. but Mercedes too has the same target for Q3 with a 2 l TDI engine and the Q7 with For example, the 2 l TDI with about 175 the same timeline. And BMW won’t just a 4.2 l TDI engine, the smallest and larg- hp offers a specific output of about 88 hp let go of its position without a fight. Given est engines of the family available in India per litre. This output compares well or the fact that all three companies are not to ascertain the foundation driving the exceeds that of some petrol cars from sim- going through any major financial crisis, TDI technology. ilar segments across the globe. one can expect them to stay at par with The architecture is primarily made up each other in terms of technology as well. of a single or two turbochargers with If Audi is to achieve its target, the com- TDI – WHAT THE THREE variable turbine geometry, which means pany will have to increase its marketshare LETTERS REFLECT the engine can respond better at low rpm in emerging countries such as China, and offer a wider spread of torque. where it already enjoys a good presence. The main aim of the TDI technology is to Cleaning up the emissions is primarily India is another such market, which can offer high fuel-efficiency and lower emis- the job of the exhaust gas recirculation

54 www.autotechreview.com (EGR), DPF and a low emission system, address local needs in various markets shorter wheelbase and lighter weight, it’s which cleans up to 90 % of nitrogen through developing more variants from a easier to drive quickly on curvy roads. oxides. Efficiency and power are single platform. With one of the rear wheels off the enhanced by a injection, ground, one gently needs to throttle to piezo injectors and turbochargers. about 1,400 rpm and the Q3 will make its The EGR technology and its working is TECHNOLOGY IN PRACTICE way through without any hiccups. On cor- quite interesting and slightly different in ners, the wide torque band couples up Audi engines, claims the company. The Not always does a technology that sounds with lesser body-roll, and the Quattro grip EGR sends back a high amount of exhaust or reads impressive, translates into signifi- makes it easier to make a correction in gas to the cylinder, which lowers the cant benefits on the road. From a com- case of an error or sudden change in amount of oxygen in the air-fuel mixture. mercial perspective, TDI technology is surface. These exhaust gases also prevent any already successful across the globe. The chemical reactions from taking place in characteristics mentioned above are easily the cylinders. The effect of both these identifiable on the road along with many OUTLOOK changes from the usual scenario is that others that haven’t been mentioned. the combustion temperature falls, result- We tested the Q3 (2l TDI) and a Q7 In Europe, diesel share of passenger cars ing in a significant reduction in formation (4.2 TDI) and have earlier driven an A7 sold is more than 50 %, and the trend is of nitrogen oxides. with the 3 l TDI engine. Despite having expected to continue in the near future. All TDI engines use a water-cooled the same powertrain technology, all three The story in India or other markets isn’t EGR system with a map-controlled cool- vehicles behaved differently, and in line different either. The need is for better ing capacity. The exhaust gases are cooled with their overall characteristics. Turbo- refined and more efficient products, and by this system on their way back into the lag is almost negligible on any TDI engine in the case of premium cars, the demand cylinder. Similar to an , the sys- and the torque is available from as low as for performance and dynamics comes in tem lowers air temperature, causing it to 1,800 rpm. The NVH levels are apprecia- as a standard requirement as well. While contract and thereby allows for more air ble and barely any vibrations get through TDI technology fulfils these requirements to be fed into the cylinder. More recircula- the cabin. and could significantly propel Audi tion of exhaust gases directly results in Given the variable geometry of the tur- towards its goal of claiming the top spot lower emissions and a lower combustion bochargers, the engines offer a wide band by 2020, it might not be enough alone. chamber temperature. of torque, resulting in a strong accelera- will need to look at a couple of Another interesting technology is the tion right up to engine rotations just short segments below its entry-level one tumble flaps, which incorporates swirl of the redline. Fuel efficiency and perfor- presently. and tumble flaps in the intake area. These mance too stood great for all three cars Access to these new segments will be flaps modulate the intake air depending within our test-cycles and the figures the key factor to bring in volumes, which on the load and engine speed, resulting in below prove that performance and effi- would contribute significantly to global a suitable swirling motion. This improves ciency can go hand-in-hand. The accelera- numbers. For TDI technology in specific, combustion efficiency, resulting in tion figure for the A7 is company claimed it would call in for more of what it has increased power while enhancing the and the test cycle for fuel efficiency nor- been undergoing since 1989 – evolution, fuel-efficiency. mally consists of a city/highway split of but from a low-cost perspective. This The common rail about 60/40 ratio. means the technology will need to be flex- makes use of high injection pressure to ible enough to be improve power and efficiency at the same Model Displacement Power 0-100 km/hr Fuel-efficiency built to a value time. The pressure can go to a maximum (Litre) (hp) (in seconds) (km/l) and not a cost, of 2,000 bar or about 29,000 psi in the rail Q3 2 175 8.5 11.8 thereby retaining injecting the fuel. All these technologies all qualities one A7 3 245 6.3 9.8 combined with sub-systems, such as associates with Q7 4.2 335 6.9 7.5 multi-hole nozzles and piezo injectors, Audi. Since improve the overall drivability and effi- beginning, TDI ciency of the engine. Adding further to all Audi engines, technology has been scalable in nature Adding to the overall dynamics is the including the TDI ones, is the Quattro all- and that is reflected by the fact that quite fact that all TDI engines feature significant wheel drive system. While the system a few engines are majorly reworked ver- lightweighting and friction-reducing meas- needs no explanation, it would be befit- sions of the older ones. How efficiently ures. This ensures a better output in terms ting to mention its working in brief. The Audi India or any of its competitors do of power and efficiency and also offers system mostly splits the power to the rear this is what will determine the market increased durability. In addition, most of and front axle in 60:40 ratio but can leader in the premium segment over the these systems can be calibrated or opti- change it depending on the surface and next eight years. mised to suit engines and vehicles of vari- grip availability. While the system works ous sizes and characteristics. This lends well on all three vehicles, it worked par- Read this article on the company with greater flexibility to ticularly well on the Q3. With the Q3’s www.autotechreview.com autotechreview November 2012 Volume 1 | Issue 11 55