2.5 TFSI: Audi’s many absolute array five-cylinder

These images are burnt into a memory of motorsport enthusiasts: Pikes Peak in a US. Summer 1987. Walter Röhrl whips his Audi Sport quattro S1 (E2) conflicting a mud highway some 4,000 meters (13,123 ft.) above sea turn as if there were no tomorrow. The atmosphere grows thinner. Both literally and metaphorically. In some places, a lane plunges downhill, 1,800 meters (5,906 ft.) into nothing. Röhrl puts that out of his mind. The convene champion loves this course. His car, a S1 with a 590 PS five-cylinder engine, climbs Pikes Peak fast and nimbly. The result: a mythological 10:47.850 minutes. At his fastest, Röhrl is clocked during 196 km/h (122 mph). His comment: “It was a rise of what we can do with a convene car.”

Actions like these have helped a mixed award-winning five-cylinder Audi engine strech cult status. “For me, it’s an engine with character,” says Armin Pelzer, conduct of Powertrain Application Development during Audi. “Other engine concepts might have their advantages over a five-cylinder engine, though they can’t compare a clarity that is totally a own.” Its sound is one critical component of that – a powerful, low resounding and pitter-patter that unleashes a clarity of pleasure.

Unmistakable sound

“That sound settlement is unique,” explains Marc Füssel, Thermodynamics/Application Development during Audi Sport. Under a hood, a 5 pistons glow adult and down in their cylinders in time with a memorable banishment order: 1 – 2 – 4 – 5 – 3. “That’s conflicting from any other engine. Particularly during aloft engine speeds and with heavier loads, it doesn’t make as many of a droning roar as a four-cylinder,” says Füssel. “Based on a giveaway inertial army of a initial and second degree, a five-cylinder engine brings a certain strange operation with it, that creates it all a some-more emotional, alive, and incorruptible.”

The core of what Audi fans have appreciated given a late 1970s has not altered given then. Even today, a ignition spacing reaches 144 degrees, for instance in a stream Audi RS 3: since of a banishment order, adjacent and non-adjacent cylinders glow alternately. That produces a really specific cadence and character. The peculiar array of cylinders creates harmonic frequencies that accompany a undertone. The engine control section also contributes to a observable sound. With a heavier load, a flaps in a empty gas tract open adult for an even fuller sound.

Successful engine judgment for a array and rallying

However, a strange ideas behind a engine were conjunction a evil using function nor a observable sound. With a initial five-cylinder Otto engine, that gathering a Audi 100 (C2) in 1976, a association with a 4 rings wanted to locate adult with a foe and strech a aloft position. The four-cylinder was supplemented with an additional cylinder in sequence to boost engine banishment and power. The ensuing 2.1 liter true five-cylinder engine had 100 kW (136 PS). A complicated fuel injection complement augmenting potency and energy delivery. Together with a all-wheel expostulate quattro and turbocharger, a five-cylinder ensured a change in Audi’s picture and success in motorsport.

With a introduction of a Audi A4 (B5) in 1994, a five-cylinder pronounced farewell to the B-segment, however a vital quip followed in 2009 – turbocharged with gasoline approach injection for aloft efficiency, low emissions, and 2.5 liter engine banishment in a Audi TT RS. The initial five-cylinder engine of a new age is indeed a elect plan for a VW Jetta, assembled by VW Mexico. For a US market, we wish to rise a strong aspirated engine with high banishment and starting torque. “For us, that was a basement for reviving a turbocharged five-cylinder tradition,” says Pelzer. Pelzer, who had only taken over as conduct of engine construction behind then, remembers that time well. “We had only finished building a initial five-cylinder inheritor engine, that was afterwards primarily transverse-mounted in a Audi TT RS,” he says. The TT RS plus, that Audi presented in 2012, even reaches 265 kW (360 PS) instead of a prior 340 PS.

Extensive redevelopment

For a new era of a Audi TT RS, Pelzer and his group totally reworked the five-cylinder in 2016. Their objectives are over ambitious: a engine brings some-more energy with a revoke weight, reduced consumption, reduction emissions, and assembled space that is even some-more compact. “At a time, we switched to an aluminum crankcase. That alone saved 18 kilograms (39.7 lbs) of weight. In all, a 2.5 TFSI engine became 26 kilograms (57.3 lbs) lighter than a prototype model,” Pelzer says. For a sporty automobile in that a engine is in front of a front axle, that is a essential cause for steering function and dynamics on racetracks or in curves.

“We built tractable camshafts into a cylinder conduct for non-static valve timing. We also introduced a H2O siphon that can be disengaged,” says Pelzer. The Audi valvelift complement (AVS) varies a cadence of a opening valves.

That way, it reduces flushing waste in a explosion cover and facilitates an optimal upsurge of empty gas to a turbocharger, quite in a revoke rev range. The formula are energetic responsiveness and augmenting torque.

Complex measures revoke inner attrition while augmenting energy output. The cylinder liners are plasma-coated; a crankshaft categorical orientation are 6 millimeters (0.2 in) smaller in diameter. The crankshaft is vale wearied and is therefore one kilogram (2.2 lbs) lighter, while a aluminum pistons have integrated channels for oil cooling.

More torque, some-more pulling energy in a new Audi RS 3

The story of a five-cylinder continues in a new Audi RS 3 Sedan and a new RS 3 Sportback. Here again, a 5 cylinders move a clarity of pleasure and even some-more pushing enjoyment. Audi is again augmenting a torque of a 2.5 TFSI by 20 in comparison with a prototype to 500 Newton meters, that is between 2,250 and 5,600 revolutions per minute. “This extended revolution speed plateau with a limit of 500 Newton meters, that starts during a low revolution speed, was a settled growth target,” Füssel explains. “That is something a motorist can directly knowledge and feel.” That is since a Audi RS 3 now accelerates out of low rev ranges faster. The engine’s limit energy of 294 kW (400 PS) is accessible progressing than before during 5,600 rpm and extends over a extended plateau to 7,000 rpm.

New modes, new pushing experiences

The numbers pronounce for themselves: with a customary Launch Control, a Sportback and a Sedan accelerate from 0 to 100 km/h (62mph) in 3.8 seconds – 3 tenths of a second faster than their predecessor. As an option, Audi can lift a electronically singular limit speed from 250 km/h (155 mph) to 280 km/h (174 mph). With a discretionary energetic package, even 290 km/h (180 mph) is probable – a Audi RS 3’s acceleration and limit speed therefore set a new benchmark in a compress segment.

“For us in development, it was about new pushing modes,” says Füssel. “For that reason, a primarily accessible RS 3-specific Audi expostulate name modes RS Performance, that is designed for racetracks, and RS Torque Rear, what is know as ‘drift mode,’ are implemented on a engine side in a controller application.” In both modes, we augmenting engine speeds as compared with Dynamic Mode to boost off-the-line performance. The stifle response is even some-more approach and has a really particular bucket shift. Moreover, drivers knowledge really late upshifting and early downshifting as good as optimal control of a linear accelerator during a peak of a curve.

In RS Torque Rear mode, a torque splitter, that is built into an Audi for a initial time, generates oversteering by putting adult to 100 percent of a rearward torque into a circle on a outward of a curve. This creates tranquil drifts probable on sealed roads. In contrariety to this really tail-heavy thrust distribution, a torque splitter ensures a many neutral probable doing in RS Performance Mode with small understeering or oversteering.

Lap record on a Nordschleife

Nürburgring in a Eifel. Summer 2021. Frank Stippler, Audi Sport racing and growth driver, is hurtling by a “Green Hell” in a new Audi RS 3. Third gear, 140 km/h (87 mph), negligence to roughly 80 km/h (50 mph), second gear, right in a curve, accelerate, a tires screech. The result: 7:40.748 minutes, a new tip speed in a compress segment.

The basement for a record is a interplay of tip technologies. The torque splitter distributes torque entirely adjustably between a back wheels – tranquil around a mixed front purchase on any of a expostulate shafts. During energetic driving, it increases a expostulate torque to a outdoor back circle with a aloft circle load. This means that on right turns, there is some-more torque on a left back circle and a conflicting on left turns. The Audi RS 3 therefore turns into a bend even improved and follows a steering angle some-more precisely.

That is quite apparent in multiple with a RS Performance pushing mode, which, with a possess engine and delivery characteristics, is specifically calibrated for a racetrack. This creates early acceleration probable on exiting a curve, enabling faster path times.