Bartek S.
Aerodynamic Ace
In just a few months, Audi’s A5 coupe will hit the market in the United States – the more powerful S5 sibling already here. First of the cars to be based on the new B8 chassis, it will be followed next fall by the next-generation A4. Those watching the new Audi offerings with interest have probably noted a distinct lack of 4-cylinder carryover. Of course there’s the FSI 4.2-liter V8 in the S5 and the A5/A4 ranges have been confirmed to have the 3.2l V6 FSI with valvelift, but those on a budget or looking for even more efficiency in the North American range are already asking for something to slot below the 3.2. Audi knows this demand is there, with several executives confirming that an all-new 2.0T-FSI is on the way. That in mind, Fourtitude recently had a chance to sample prototype versions of the A5 with experimental versions of the all-new engine.
This wasn’t the typical test drive of a new Audi of which we typically report. There wasn’t a long drive with well-researched driver-oriented routes or several days to spend in a car and learn its nuances. These weren’t made-for-prime-time production models but engineering test mules built to show off new technologies. Journalists were invited to try out new fuel-saving technologies from Volkswagen and Audi – one A5 ran on ethanol, the other made use of engine start-stop technology with a ‘micro-hybrid’ system that uses energy regeneration during braking and free wheeling for improved efficiency.
Thanks to using bio-ethanol in the ethanol A5, the first coupe was good for 75% better CO2 emissions. Even more applicable in daily use, the start-stop equipped A5 with its regenerative brake system is good for 40 mpg. Sources at Audi say the ethanol variant was more to show that it could be easily done, but hardware such as the regenerative braking and start-stop technology are more likely to see near-term production.
Short stints around downtown San Francisco were provided in order to learn the daily drivability of experimental drivetrains such as these – not optimum for learning driving dynamics, but the two A5s were far from production spec anyway. More importantly, the 2.0T hearts that beat under the hoods of these coupes were from the Volkswagen Group’s latest EA 888 engine family of 4-cylinders and also equipped with valvelift. Essentially, if you ignore the experimental fuels or components, the specifications of these two motors are close to what will go into full production in the A4 and A5 in the near term and should see duty eventually in transverse applications such as the A3 and TT. Non-valvelift versions of the EA 888 series 2.0T, we hear, are already being fitted to production A3s.
The EA 888 engine project was the brainchild of former Audi AG board member Wolfgang Hatz. Hatz who has since followed Martin Winterkorn to Audi parent Volkswagen AG and taken a post as head of drivetrains for the entire company. Given that, it’s not surprising that versions of this more efficient, more refined and more cost-effective engine family will see duty across all group brands from Audi and SEAT to Skoda and Volkswagen.
The first of the EA 888 series to see production was the 1.8T-FSI available in European market A5s. Changes in the 1.8T-FSI confirm many of the internal detail changes that will be found in future 4-cylinder applications.
One of the most significant changes to this new family is the incorporation of a chain-based drive. Building on lessons learned in developing Audi’s 4.2l V8 for compact applications like the S4, use of inverted-tooth chains to drive camshaft, oil pump and balance shaft operation resulted in lowered noise levels, and lowered frictional loss while the chain system’s useful life matches that of the engine.
Seldom seen in four-cylinder applications, EA 888 also makes use of balance shafts integrated into the lighter grey cast iron crankcase. Unlike other balance shaft designs, the new configuration from Audi combines for improved cost and lower noise, as well as optimized weight and crank case stiffness. Eight counterweights have also been used in the crankshaft for optimum internal balance.
The EA 888 family is also quite flexible. It’s suitable for production anywhere in the Volkswagen Group’s network of engine production facilities. The engine family can take a wide range of fuel quality, allowing it to be used in any of the markets in which the Volkswagen Group sells cars. Designed to be lighter than the equivalent displacement engines they replace, the EA 888 family is also sturdy enough for applications on the liberal side of 134 hp per liter. They also boast more dynamic torque buildup that’s more pleasurable to drive and consumes less fuel in the process.
Even more components have been added to increase efficiency and lower weight. There’s a variable oil pump, 12 percent more efficient due to lowered friction. A variable volume steering pump nets similar gains. Also, fuel pressure in the production 1.8T-FSI is up to an improved 150 bar.
Planned for the higher-cost applications of the 2.0T-FSI such as the A4 and A5 are 2.0T-FSI engines equipped the company’s unique new valve control system known as valvelift. This component alone is good for five percent better fuel economy, but it also further augments torque, making turbocharged applications like our A5 2.0T mule feel even more like a brawny naturally aspirated V6.
Unlike other bulky and complex systems, valvelift is cleverly simple, with control directly on the camshafts that allows for lightning quick adjustment – just two turns of the crankshaft. Employment of valvelift provides the ability for the engine to dethrottle intake under partial load. By varying valve patterns of the two inlet valves, the charge is specifically tuned for optimized consumption and power. Where this seriously translates into fuel savings is driving at constant speeds under partial loads – basically highway and even high-speed autobahn cruising.
Currently, Audi claims the system is stable for engine speeds reaching 7,200 rpm, suggesting a wide compatibility for valvelift applications in Volkswagen Group offerings, but not yet compatible with high-revving mills like the 4.2-liter V8 found in the RS 4 and R8.
The most powerful of the two EA 888 2.0T-FSI A5s on hand was rated at 210 hp – likely not far from a production number and not terribly ground-breaking. Where the next-gen 2.0T really shatters the schema of the outgoing motor is torque. At 236 lb/ft, the Ethanol-powered A5 was closest to production numbers sources have told us will be on the up side of 250 – impressive, and enough to easily rival the current 3.2 V6’s 243 lb/ft.
So how does it drive? In the streets around downtown San Francisco, torque was plentiful and came on in a linear fashion improved over the elder 2.0T. Thought he buzziness of the current 2.0T isn’t gone entirely, refinement levels over the old are markedly improved.
Most Audis sold today are quattro, but both A5 mules on hand for driving were front-wheel drive FrontTrak models - optimized for better fuel efficiency. Under hard acceleration, the FrontTrak A5 spins its wheels in a manner consistent with current 2.0T front-wheel drivers equipped with hotter aftermarket ECUs. Though the Audi’s multi-link front suspension design admirably minimizes torque steer, getting the power to the ground remains an issue – one most enthusiasts would say is a good problem to have. With so much torque, this engine really would be better paired with Audi’s quattro all-wheel drive system.
In mainly stop-and-go traffic around downtown San Francisco, there was little-if-any chance to push the A5 in corners and get a feel of handling, though we’d guess Audi executives didn’t want a super pricey engineering prototype sliding around San Fran streets anyway. Still, we can’t help but think that 2.0T A5s and A4s will handle quite well.
This new engine is even lighter weight than the current 2.0T. That lighter engine is wrapped in the more neutrally-handling packaging of the B8 platform, set on Audi’s new Modular Longitudinal Platform (MLP) with its engine placement lower and further back in the chassis. We’ve already sampled 3.2, 3.0 TDI and S5 versions, cars with more weight in the nose than the 2.0T though still manage to be more neutral than any B,C or D-based Audi of yore.
Due to the short test circuits, gauging real world fuel economy was also impossible. Materials provided by Audi say the Ethanol-based car, differing mainly in ECU programming from what we’ll first see, gets an estimated combined fuel consumption of 31 mpg when mated with our car’s manual 6-speed transmission and will knock out a 0-60 run in 6.7 seconds with this optimized more-frugal-than-fast setup. Interestingly, the lower reported power levels (210 hp, 207 lb/ft) of the start-stop high efficiency A5 supposedly net a faster 6.6 seconds to 60 mph and 40 mpg combined consumption.
While 2.0T-FSI versions of the A5 and A4 hit the market, they’re not expected to be touted as ethanol compatible and may or may not yet include components such as regenerative braking, though full production versions of both are expected in the American market sometime next fall. While big displacement versions may be both sexier and more luxurious, a growing demand for low consumption further driven by recent CAFE standards changes should make A5 and A4 2.0T models popular with buyers even before improved straight-line and cornering performance is considered.
http://www.fourtitude.com/news/publish/Features/article_3658.shtml
and the performance figurers are a step up from the 1.8t
