Audiâs new high efficiency TFSI petrol engine: the knowledge
At the Vienna Motor Symposium, Audi revealed details of its all-new 2-liter TFSI four-cylinder power unit. Here are some of the technical highlights
Audi is committed to efficient petrol engines
Audi’s new 2-liter TFSI produces 190ps and 320Nm, but registers fuel consumption in excess of 56mpg (5.04l/100km) on the New European Driving Cycle (NEDC). It is, the OEM claims, the most petrol-powered unit in its class.
Audi is focused on ‘rightsizing’
Reducing displacement and engine speed is one thing, but an engine needs to be partnered with the right vehicle. “We’re now taking a crucial step further with rightsizing,” says Ulrich Hackenberg, member of the board of management for technical development at Audi. “Rightsizing thus involves the optimal interplay of vehicle class, displacement, output, torque and efficiency characteristics under everyday conditions. Our new 2.0 TFSI is a prime example of Vorsprung durch Technik.”
Torque is available at low revs
The four-cylinder engine draws 320Nm of torque from a displacement of 1,984cc, and this torque is available from 1,450 to 4,400rpm, providing strong and constantly accessible pulling power.
There’s a new combustion method
At its core, the new engine’s principle is comparable to the Miller cycle. Audi engineers have further developed that method in crucial ways, however, increasing efficiency. Intake time has been significantly shortened (140° crank angle (CA) rather than 190 to 200° CA). Higher boost pressure on the inlet side means the engine attains optimal cylinder charges despite this reduction. The intake valve also closes earlier – well before bottom dead center is reached. This lowers the medium pressure, allowing a high, efficiency-boosting compression ratio. In the partial load range, an additional injection upstream from the intake valve yields an efficient mixture formation that is already complemented by the direct injection in the intake manifold and in the combustion chamber. The Audi Valvelift System (AVS) on the inlet side allows a short intake time at partial load and a longer time at higher loads (full load: 170° CA).
There’s other tech involved too
Beyond the new combustion method, the new engine, which weighs in at 140kg, avails itself of other efficiency technologies. For example, the coolant flow is controlled so as to greatly shorten the engine warm-up time. The integration of the exhaust manifold into the cylinder head also brings benefits, as does the use of low-friction engine oil.
The new engine will be in use soon
The new power unit will be installed in the new A4 by the end of 2015. Audi plans to introduce the new generation of engines in other model series.
May 11, 2015
11 May 2015
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