Audi has not only refreshed the design of the S5, but also reworked its engine to offer a rare combination of power and efficiency. On paper, the S5 boasts of impressive specifications but how well it would pan out in the real world was yet to be evaluated. We take a dive into what Audi has tweaked under the hood.
Audi’s new S5 wears a fresh look thanks to its redesigned body coupled with changes made under the hood. The 3 l V6 engine has been completely redesigned and now boasts of higher power and torque figures. The engine now churns out 21 hp and 60 Nm more than the previous engine offered in the S5. The redesigned engine also propels the S5 to 100 km/h from standstill in a mere 4.7 s, nearly 0.4 s quicker than what the previous motor achieved.
But that’s not all, Audi has also made the reworked V6 5 % more efficient as compared to its predecessor. The V6 engine, which boasts of high power figures and a wide torque band, now delivers 354 hp at 5,400 rpm going up to 6,400 rpm and belts out a whopping 500 Nm of torque as low as 1,370 rpm ranging to 4,500 rpm.
BURNING IT THE RIGHT WAY
The 3 l V6 mill features a new combustion process known as the B-cycle, which utilises high pressure injection valves centrally arranged in combustion chambers. This process uses a shortened compression stroke, which in turn, caters to the use of an engine process with a significantly higher geometric compression ratio. The power stroke in the new engine is relatively longer as compared to the compression stroke, thus allowing an increase in combustion and engine efficiency. The high compression ratio also affects the tendency of an engine to knock, which in turn, limits maximum achievable output.
To maintain efficiency and output orientation, the company has incorporated the AVS (Audi Valve Lift System), which at part load, enables short intake aperture duration of 130° of camshaft angle combined with an early closure of the intake valve. At higher loads, the engine can switch to a camshaft shape with a longer aperture duration and greater intake valve lift to achieve maximum output from each cylinder. In a real world scenario this translates into decent mileage figures from a performance-oriented sedan and the ability to almost instantaneously leap forward, when you floor the accelerator.
Essentially, the redesigned 3 l V6 engine now weighs 172 kg, 14 kg lighter than its predecessor. Audi has built the engine with an aluminium alloy that has been cast using a complex sand casting process. The cylinder crankcase has integrated thin-walled cylinder liners of grey cast iron and the engine features new friction-reducing rings developed for the aluminium pistons.
Audi is using separate coolant circuits for the cylinder head and the crankcase, thus improving the efficiency of the thermal management system. The exhaust manifold has also been integrated into the cylinder head and the coolant circulates around it. The system reduces exhaust gas temperature when the engine is warm. This improves fuel efficiency, especially when you are really pushing the vehicle to its limits.
EFFICIENT EXHAUST SCAVENGING
While the previous motor powering the S5 used a mechanical compressor, the new unit gets a twin scroll turbocharger. The exhaust manifold individually collects gases from the two separate cylinder banks, which only merge before the turbine wheel. This system has an enhanced exhaust scavenging effect with better pressure distribution to the exhaust ports and a more efficient delivery of exhaust gases to the turbine. The layout helps achieve an earlier and more powerful torque build-up.
The turbocharger has been strategically placed between the 90° V of the cylinder banks. The intake side faces outward, while the exhaust side faces inward, catering to compact construction and short gas flow paths for minimal flow loss. The construction empowers the driver with an extremely spontaneous and direct response. The Audi S5 also features the drive-by-wire technology.
SMOOTH & WELL-CONTROLLED TRANSMISSION
Audi has married the longitudinally mounted engine to an 8-speed tiptronic automatic transmission. The tiptronic, a torque converter transmission, boasts of smooth shift action and starting performance. The 8-speed unit bolted onto the S5 keeps the jumps in engine speeds between gears low, with the engine mostly running at optimum capacity. While testing the S5 in traffic and some open stretches we found the gearshifts to be smooth, quick and flexible as per driver inputs.
The Audi S5 comes with a permanent all-wheel drive Quattro set-up and a self-locking centre differential. Under normal driving conditions, power is distributed in a 40:60 ratio between the front and rear axles. This set-up ensures a sporty and thrilling drive experience. The centre differential is capable of delivering a maximum of 60 % power to the front and 80 % power to the rear axles, when necessary.
Audi has also built into the system an electronic differential lock, which controls wheel spin using the brakes. On the braking front, the German four-ring brand has built a dual circuit brake system, which is split between axles. Audi is also offering ABS (antilock brake system) with EBD (electronic brake force distribution), EDL (electronic differential lock), ASR (traction control), ESC (electronic stabilisation control) and ventilated discs. The braking set-up is progressive and powerful, bringing the sedan down to zero in a few seconds. Combined with the Quattro all-wheel drive set-up and the self-locking centre differential the Audi S5 delivers tremendous amounts of control.
To sum it up, the Audi S5 was always sporty and refined but new technological updates and mechanical redesigns in the key components have given more bite to the bullet that is the S5. Taking the CBU route to India, Audi S5 stands out now for more power, efficiency, control, comfort and refinement, thus making the package a rare combination.
TEXT: Joshua David Luther
PHOTO: Bharat Bhushan Upadhyay/ Audi