The output of the 3.0 litre straight-six cylinder engine with high-precision direct injection and Valvetronic has been further increased with the aid of a revised turbocharging system comprising two new ALPINA specific turbochargers and a new high-performance cooling system. The new BMW ALPINA B4 S Bi-Turbo now delivers 324 kW (440 hp) between 5500 rpm and 6250 rpm and a maximum torque of 660 Nm from 3000 rpm to 4500 rpm.
The new engine particularly impresses in the mid-range with an effortless power delivery in addition to an eager willingness to rev to 7000 rpm. Coupled to the excellent ZF 8-Speed Sport-Automatic Transmission it propels the new BMW ALPINA B4 S Bi-Turbo Coupe in just 4.2 seconds from 0 to 100 km/h and on to a top speed of 306 km/h. BMW Efficient Dynamics technologies such as Auto Start Stop and Sailing contribute to an exemplary fuel consumption of only 9.1 l/100 km and 207 g/km CO2 combined measured to ECE norm (depending on the model).
To achieve the new BMW ALPINA B4 S Bi-Turbo’s characteristic, torque driven and spontaneous power delivery without sacrificing fuel efficiency necessitates state-of-the-art engine technology in a clever package. The application of Bi-Turbo charging provides excellent throttle response and pick-up due to the low mass inertia of smaller turbocharger running gear while generating sufficient throughput for top-end performance. The design and construction of the excellent BMW 3.0 litre straight-six cylinder (N55) engine serves as a starting-point for a specially cast aluminium crankcase with reinforced bed plate and Bi-Turbo capable flanges. The latter facilitate the mounting of two turbochargers along with their oil and water feeds and a close-coupled catalytic converter arrangement.
This latest iteration of the 3.0 litre straight-six cylinder engine receives new ALPINA specific turbochargers for even more output and a new piston crown cooling system. ALPINA air intake ducts guide the air with minimal losses from the air intake via the air filter housing to the turbochargers. A high-capacity intercooler with optimised collector boxes made from aluminium allows the full exploitation of the engine’s output potential. The high-performance cooling system has been further adapted concordant to the latest increase in engine output – the external water cooler and external oil cooler have grown in capacity by more than 15 % and 35 % respectively.
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The construction and design of the stainless steel exhaust system, developed in cooperation with Akrapovič, guarantees an elegant look and a very emotional soundtrack. The silencer volume is reduced to a minimum in order to optimise the flow of exhaust gases and to save weight - along with other measures the intended result is also a powerful, baritone sound. An intelligent exhaust valve makes it possible to successfully achieve the balancing act between audible pleasure and long-distance comfort. The exhaust valve is closed when the Dynamic Performance Control is set to Comfort mode and opens depending on load and engine speed. In contrast, it is permanently open in Sport mode, generating an exciting sound experience especially under acceleration.