New combustion process: higher efficiency
A new combustion process developed by Audi makes the 3.0 TFSI particularly efficient. It is based on the so-called “B cycle” process in combination with high-pressure injectors centrally located in the combustion chambers.
With its artificially shortened compression phase, the B cycle enables an engine process with a significantly higher base compression ratio. Combined with a power stroke that, while normal, is longer relative to the compression stroke, this allows for more efficient combustion and increased engine efficiency.
Under part load, the Audi valvelift system enables a very short intake aperture duration of 130 degrees of camshaft angle coupled with the early closure of the intake valve. This shortens the intake phase. At higher loads, the system switches to a camshaft contour with a longer opening time and a larger valve stroke. The engine then operates with a normal compression ratio and maximum throughput.
Turbocharger: separate exhaust gas flows
The turbocharger, which replaces the mechanical compressor of the previous engine, operates according to the twin-scroll principle. The exhaust branches of the two cylinder banks run separately in the exhaust manifold and in the turbocharger housing, and only merge before the turbine wheel. This technology improves the flow characteristics for more spontaneous turbine response, and is key factor behind the early and powerful development of torque.
The turbocharger is located within the 90-degree V of the cylinder banks. Accordingly, the exhaust side is on the inner side of the cylinder heads and the air intake on the outer side. This arrangement enables compact construction and short gas flow paths with minimal flow losses, thus the 3.0 TFSI responds extremely spontaneously and directly.