Test Drive Audi Engine Lineup - Part 1: 1.8 TFSI
Test Drive

Test Drive Audi Engine Lineup - Part 1: 1.8 TFSI

Test Drive Audi Engine Lineup - Part 1: 1.8 TFSI

The range of drive units of the brand is the epitome of incredibly high-tech solutions.

A series about the most interesting cars of the company

If we are looking for an example of a forward-looking economic strategy that ensures the company's sustainable development, then Audi can be an excellent example in this regard. In the 70s, hardly anyone could have imagined the fact that now the company from Ingolstadt will be an equal competitor to such an established name as Mercedes-Benz. The answer to the reasons can be largely found in the brand's slogan "Progress through technology", which is the basis of the successfully traversed difficult path to the premium segment. An area where no one has the right to compromise and only offers the best. What Audi and only a handful of other companies can do ensures that they are in demand for their products and achieve similar parameters, but also a huge burden, requiring constant movement on the edge of a technological razor.

As part of the VW Group, Audi has the opportunity to take full advantage of the development opportunities of a huge company. Whatever problems VW has, with its annual R&D spending of almost 10 billion euros, the group tops the list of the 50 highest invested companies in the field, ahead of giants such as Samsung Electronics, Microsoft, Intel and Toyota (where this value amounts to just over 7 billion euros). By itself, Audi is close to BMW in these parameters, with their investment of 4,0 billion euros. However, part of the funds invested in Audi comes indirectly from the general treasury of the VW group, since the developments are also used by other brands. Among the main areas of this activity are technologies for the production of light structures, electronics, transmissions and, of course, drives. And now we come to the essence of this material, which is part of our series, representing modern solutions in the field of internal combustion engines. However, as an elite division of VW, Audi also develops a specific line of powertrains designed primarily or exclusively for Audi vehicles, and we will tell you about them here.

1.8 TFSI: a model of high technology in every respect

Audi's history of in-line four-cylinder TFSI engines dates back to mid-2004, when the world's first EA113 direct injection petrol turbocharger was released as the 2.0 TFSI. Two years later, a more powerful version of the Audi S3 appeared. Development of the modular concept EA888 with a camshaft drive with a chain practically began in 2003, shortly before the introduction of the EA113 with a timing belt.

However, the EA888 was built from the ground up as a global engine for the VW Group. The first generation was introduced in 2007 (as 1.8 TFSI and 2.0 TFSI); with the introduction of the Audi Valvelift variable valve timing system and a number of measures to reduce internal friction, the second generation was noted in 2009, and the third generation (2011 TFSI and 1.8 TFSI) followed at the end of 2.0. The four-cylinder EA113 and EA888 series have achieved incredible success for Audi, winning a total of ten prestigious International Engine of the Year awards and 10 Best Engines. The task of the engineers is to create a modular engine with a displacement of 1,8 and 2,0 liters, adapted for both transverse and longitudinal installation, with significantly reduced internal friction and emissions, meeting new requirements, including Euro 6, with improved performance. endurance and reduced weight. Based on the EA888 Generation 3, the EA888 Generation 3B was created and introduced last year, operating on a principle similar to the Miller principle. We will talk about this later.

This all sounds good, but as we'll see, it takes a lot of development work to achieve it. Thanks to the increase in torque from 250 to 320 Nm compared to its 1,8-litre predecessor, designers can now change gear ratios to longer ratios, which also reduces fuel consumption. A huge contribution to the latter is an important technological solution, which was then used by a number of other companies. These are exhaust pipes integrated into the head, which provide the ability to quickly reach operating temperature and cool gases under high load and avoid the need to enrich the mixture. Such a solution is extremely rational, but also very difficult to implement, given the huge temperature difference between the liquids on both sides of the collector pipes. However, the advantages also include the possibility of a more compact design, which, in addition to reducing weight, guarantees a shorter and more optimal gas path to the turbine and a more compact module for forced filling and cooling of compressed air. Theoretically, this also sounds original, but the practical implementation is a real challenge for casting professionals. To cast a complex cylinder head, they create a special process using up to 12 metallurgical hearts.

Flexible cooling control

Another important factor in reducing fuel consumption is associated with the process of reaching the operating temperature of the coolant. The intelligent control system of the latter allows it to completely stop its circulation until it reaches the operating temperature, and when this happens, the temperature is constantly monitored depending on the engine load. Designing an area where coolant floods the exhaust pipes, where there is a significant temperature gradient, was a huge challenge. For this, a complex analytical computer model was developed, including the total composition of the gas / aluminum / coolant. Due to the specificity of strong local heating of the liquid in this area and the general need for optimal temperature control, a polymer rotor control module is used, which replaces the traditional thermostat. Thus, at the heating stage, the circulation of the coolant is completely blocked.

All external valves are closed and the water in the jacket freezes. Even if the cabin needs to be heated in cold weather, the circulation is not activated, but a special circuit with an additional electric pump is used, in which the flow circulates around the exhaust manifolds. This solution allows you to provide a comfortable temperature in the cabin much faster, while maintaining the ability to quickly warm up the engine. When the corresponding valve is opened, intensive circulation of fluid in the engine begins - this is how quickly the operating temperature of the oil is reached, after which the valve of its cooler opens. The coolant temperature is monitored in real time depending on load and speed, ranging from 85 to 107 degrees (highest at low speed and load) in the name of a balance between friction reduction and knock prevention. And that's not all - even when the engine is off, a special electric pump continues to circulate the coolant through the boil-sensitive shirt in the head and turbocharger to quickly remove heat from them. The latter does not affect the tops of shirts in order to avoid their rapid hypothermia.

Two nozzles per cylinder

Especially for this engine, in order to reach the Euro 6 emission level, Audi is introducing for the first time an injection system with two nozzles per cylinder - one for direct injection and the other for the intake manifold. The ability to flexibly control the injection at any time results in better mixing of fuel and air and reduces particulate emissions. The pressure in the direct injection section has been increased from 150 to 200 bar. When the latter is not running, fuel is also circulated by bypass connections through injectors in the intake manifolds to cool the high pressure pump.

When the engine is started, the mixture is taken up by the direct injection system, and double injection is performed to ensure rapid heating of the catalyst. This strategy provides better mixing at low temperatures without flooding the cold metal parts of the engine. The same goes for heavy loads to avoid detonation. Thanks to the exhaust manifold cooling system and its compact design, it is possible to use a single-jet turbocharger (RHF4 from IHI) with a lambda probe in front of it and a housing made of cheaper materials.

This results in a maximum torque of 320 Nm at 1400 rpm. Even more interesting is the power distribution with a maximum value of 160 hp. is available at 3800 rpm (!) and remains at this level up to 6200 rpm with significant potential for further increase (thus installing different versions of the 2.0 TFSI, which increases the level of torque in high ranges). Thus, the increase in power compared to its predecessor (by 12 percent) is accompanied by a decrease in fuel consumption (by 22 percent).

(to follow)

Text: Georgy Kolev

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