The turbocharged 3.0 TFSI in the Audi S4* and S4 Avant* is an engine that has been redeveloped from the ground up. It combines sports car performance with a new levels of efficiency and also impresses with high power, ample torque, spontaneous response and a sonorous sound.
From its 2,995 cc of displacement, the V6 TFSI engine with 260 kW (354 hp) produces 15 kW (21 hp) more than the engine in the previous model. It transfers 500 Nm (516.3 lb‑ft) of torque (60 Nm (44.3 lb‑ft) more) to the crankshaft at a low 1,370 revolutions per minute. This torque is constant up to 4,500 rpm. The NEDC fuel consumption of the new 3.0 TFSI in the S4 is just 7.3 liters per 100 km (32.2 US mpg) – with a CO2 equivalent of 166 grams per km (267.2 g/mi). The S4 Avant has a fuel consumption of 7.5 liters per 100 km (31.4 US mpg) and therefore attains a CO2 figure of 171 grams per km (275.2 g/mi). Fuel economy has been improved five percent compared to the previous model.
New combustion method: higher level of efficiency
The key factor in successfully attaining efficiency is the new combustion method that originated in the V6 3.0 TFSI from Audi. It is based on what is known as the B-cycle, which is similar to the process used in the Audi A4 2.0 TFSI with 140 kW (190 hp)* and utilizes the high-pressure injection valves that are arranged centrally in the combustion chambers.
In the V6 TFSI as well, the shortened compression phase of the further developed combustion method enables an engine process with a significantly elevated geometric compression ratio. Efficiency benefits have been achieved in combination with a normal expansion phase that is longer than the compression phase, improving the engine’s efficiency.
Normally, this type of modification would result in significantly reduced chamber filling, and the high compression would increase the tendency to engine knock that would significantly reduce the attainable power. However, the Audi valvelift system resolves the confict between efficiency and power goals. In the part-load region, it enables very short intake valve opening times of 130 crankshaft degrees while simultaneously closing the intake valves early. At higher loads, the inlet valves can be shifted over to a camshaft contour with a longer opening time and larger valve stroke that maximizes engine power.
Turbocharger: separate exhaust gas streams
The turbocharger, which replaces the mechanical supercharger of the previous engine, operates according to the twin scroll principle. The exhaust branches of the two cylinder banks run separately in both the exhaust manifold and turbocharger housing, and they do not merge until just before the turbine wheel. This technology avoids undesirable interactions between the two gas streams, and it makes a large contribution toward early and strong torque build-up.
The turbocharger is placed inside the 90-degree V of the cylinder banks instead of the usual location outside next to the crankcase. Accordingly, the exhaust side is on the inner side of the cylinder heads and the intake side on the outer side. This layout enables compact construction and short gas flow paths with minimal flow losses – as a result, the 3.0 V6 TFSI responds extremely spontaneously and directly.
Less weight: reduced by 14 kg (30.9 lb)
A fundamental redesign of the V6 TFSI has lowered its weight by 14 kg (30.9 lb) to 172 kg (379.2 lb). The crankcase, which is produced from an aluminum alloy in a complex sand-casting process, integrates thin-walled gray cast iron cylinder liners. This reduces friction in interplay with newly developed rings for the aluminum pistons.
Another key efficiency component is thermal management. The crankcase and cylinder head have separate coolant circulation loops. After a cold start, the switchable water pump controls the flow of coolant through the engine to bring the oil up to its operating temperature quickly. The exhaust manifold is integrated in the cylinder head, and coolant is circulated around it, which helps to warm up the engine quickly. When the engine is warm, the system reduces the exhaust gas temperature, which in turn reduces fuel consumption, especially when driving in a sporty style.
The equipment and data specified in this document refer to the model range offered in Germany. Subject to change without notice; errors and omissions excepted.