The new BMW Alpina B4 Bi-Turbo Coupé

Wednesday, 20th November 2013 - Alpina Burkard Bovensiepen GmbH + Co

Coupés from Alpina have always appealed to a small but particularly loyal circle of enthusiast drivers who share a passion for understated elegance combined with maximum performance and a sophisticated driving experience. The design of the BMW Alpina B4 Bi-Turbo Coupé combines muscular and delicate elements in one chic silhouette.

The Coupé is both longer, wider and significantly lower than the Saloon. Its profile rakes from an imposing, muscular front accentuated with bold lines to a clean and stylish rear.

The front spoiler, with subtle Alpina lettering, integrates seamlessly into the dynamic front apron which is characterised by large air intakes for the cooling system of the turbo-charged engine as well as the high-performance brake system. Together with the rear spoiler the Coupé’s aerodynamics are optimised for excellent high-speed stability while simultaneously maintaining a low drag coefficient.

It is almost as if the low, elongated silhouette of the Coupé was shaped to complement the 20” Alpina Classic wheels. Their timeless, twenty spoke design with hidden air valves suit the B4 Bi-Turbo exceptionally well. Blue brake callipers with ALPINA lettering and signature twin tailpipes complete the appearance.

The 2979cc straight-six cylinder engine with high-precision direct injection, Valvetronic and Bi-Turbo charging delivers 410hp (301kW) between 5500rpm and 6250rpm and a maximum torque of 600Nm at only 3000rpm. In fact 550Nm are available across an impressively wide range between 2200rpm and 5200rpm. Mated to the excellent ZF 8-Speed Sport-Automatic transmission means that the new BMW Alpina B3 Bi-Turbo and B4 Bi-Turbo models are never lacking in forward momentum - power can be called upon at all times in order to enjoy that typical, effortless Alpina driving experience.

The new B4 Bi-Turbo Coupé accelerates from 0 to 100km/h (0 - 62mph) in just 4.2 seconds, passing the 200km/h mark in 14 seconds on the way to a top speed of 305km/h. At the same time the powertrain, which features Valvetronic and Start Stop, boasts class leading economy figures with a combined consumption of only 7.6 litres per 100 kilometers and CO2 emissions of just 177g/km.

The prerequisite for these impressive values is a high-tech engine which exhibits its own unique characteristics thanks to a significant number of stand-alone features. With the aim of achieving excellent responsiveness, high output across the entire rpm range and an improvement in fuel consumption, a Bi-Turbo engine configuration was required. This type of turbocharging has the benefit of providing very good response and pick-up due to the low mass moment inertia of the turbocharger’s running gear and sufficient rate of air-flow for spontaneous power delivery.

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 block with Bi-Turbo capable flanges. These enable the mounting of two turbochargers along with required oil and water connections and a close-coupled catalytic converter arrangement. ALPINA specific NGK spark plugs and a forged steel high-strength crankshaft guarantee long-lasting stability.

Always-on power delivery and excellent throttle response are aided by an electronically controlled bypass valve system. Specially constructed and de-throttled, i.e. flow and cross-section optimised, air intake ducts guide the air with minimal losses from the air intake via the air filter housing to the turbochargers. On the fuel side, a high-performance high-pressure fuel pump ensures the right throughput. Optimal utilisation of the output is provided by a high-capacity intercooler with flow-optimised collector boxes made from aluminium. Coolant cooler, additional separate coolant and engine oil coolers as well as a high-performance cooling fan ensure the thermal stability of the cooling system in all conditions.

Inspired by the pleasure that the 8-Speed Sport-Automatic transmission with Switch-Tronic offers in the larger BMW Alpina models, the so-called 8HP70 transmission has been extensively adapted to suit the performance characteristics of the new B3 and B4 Bi-Turbo models.

In actual fact, the high power output and torque of the Bi-Turbo combine so well with this transmission that performance figures usually associated with much larger but less efficient engines are achieved. Furthermore, this transmission excels in disciplines often assumed to be incompatible and offers an optimum driving experience in every situation. To this end, three shift modes are available: Automatic (D), Sport (S) and Manual (M).

In Automatic (D) Shift Mode the focus is strictly on driving comfort. The transmission changes gears quickly and with no noticeable interruption to the delivery of power. The torque of the engine enables consumption-optimised 'surfing‘ in high gears even at very low speeds and in urban driving environments. Even at higher cruising speeds rpms will remain low, for example 2500rpm at 170km/h in 8th gear, increasing long-distance driving comfort significantly.

Sport (S) Shift Mode noticeably shortens the time it takes for the next gear to engage and depending on engine load significantly moves the shift points up the rev range. Accelerator inputs are carried out immediately, full throttle i.e. kick-down will implement multi-simultaneous downshifts and optimal acceleration. When combined with the Sport or Sport+ setting of the Drive Performance Control, which modifies the drive and chassis setup, gearshifts are even quicker.

Activating the Manual (M) Shift Mode using the Switch-Tronic buttons on the back of the steering wheel, allows the driver to take control and shift gears when suitable or necessary. A special feature of the Sport, Sport+ and DSC Off setting is the suppression of automatic up-shift in Manual (M) Shift Mode – hereby the selected gear is held into the rpm limiter and the transmission will not up-shift into a higher gear.

Abundant torque allows the use of a long rear axle ratio which in combination with the 8-Speed Sport Automatic transmission and Auto Start Stop contributes significantly to achieving excellent fuel economy. Top speed is achieved in 7th gear. Additional hardware modifications for dealing with output and torque include reinforced front and rear axle differentials, high-strength output and drive shafts and a high-torque transmission gear unit.

Exhaust System
The stainless steel exhaust system which was developed in collaboration with Akrapovic is 7.5kg lighter in comparison to its predecessor. The resonant, sporty sound of the exhaust system is controlled by an intelligent exhaust valve. This offers the driver the possibility to influence the sound experience via the Drive Performance Control and facilitates the balancing act between emotional soundtrack and long-distance comfort. In Comfort mode the exhaust valve remains closed up to 2500 rpm, beyond which it opens depending on engine load and rpm. In Sport mode, however, the valve is permanently open and the B3 Bi-Turbo thrills with its distinctive aural character under hard acceleration – when additionally selecting Sport (S) or Manual (M) Shift Mode the exhaust will deliver an occasional burble on the overrun.

The suspension set-up of the new B4 Bi-Turbo provides great ride-quality and comfort while simultaneously offering sharp and dynamic handling. The adaptive Alpina sport suspension solves this conflict of interest by means of electronically adjustable dampers in collaboration with performance springs, bump stops and stabilisers. The system allows the driver to use the Drive Performance Control (Eco Pro, Comfort, Sport, Sport+) to select the suspension setting and driving dynamics to match his mood.

The longer wheelbase and wider track at the front and rear provide the B4 Bi-Turbo Coupé with a more dynamic character from the outset. Subtle adjustments to camber, toe-in and elastokinematics result in a neutral chassis and very balanced handling. The 20” Alpina Classic wheels with Michelin Pilot Super Sport tyres combined with a front strut brace accentuate the Coupé’s direct and precise turn-in.

The Drive Performance Control settings also influence other parameters which effect driving dynamics, such as the electric power steering (Servotronic) and the driving stability control (DSC and DTC) system. The latter is subject to a software coding which takes into account the specifics of the Alpina suspension and chassis.
The Variable Sports Steering from BMW, which comes as standard, has a progressive steering rack providing steering stability at high speeds but which requires significantly less steering input (turns of the wheel) when manoeuvring and parking.

Deceleration is taken care of by an 18“ high-performance brake system with 370mm discs at the front and 345mm discs at the rear. Aluminium callipers (4-piston on front axle, 2-piston on rear axle) painted in blue and with Alpina lettering, in conjunction with high-performance pads, ensure fading stability and optimal pedal feedback.

All-Wheel Drive
The optional all-wheel drive (not available in RHD markets) system offers even more traction and active safety in every and any driving situation. It exploits the technical potential of BMW’s xDrive system and its intelligent and dynamic distribution of drive power which continuously and fully variable distributes torque between the front and rear axle within milliseconds.

The torque distribution algorithm communicates with the Alpina DME and the adaptive suspension system to increase driving dynamics and agility, particularly during high lateral acceleration, creating unexpected sporty and neutral handling despite all-wheel drive. Besides ensuring optimal traction during acceleration, the system also permanently monitors a wide range of sensory inputs – for example steering angle, lateral acceleration, yaw angle and speed – to distribute torque so as to achieve optimum propulsion and safety for example on snow or to counteract sudden changes in road surface friction.

Equipment & Manufacturing
The new B4 Bi-Turbo Coupé comes with an extensive list of standard equipment, including leather upholstery, electrically adjustable heated sports seats, automatic climate control, xenon headlights, rain sensor and cruise control.

The interior is dominated by refined materials and offers an exclusive ambience. The door sills, floor mats, emblems in the seatbacks, instrumentation and a hand-stitched sports steering wheel in the finest Lavalina leather make discreet references to the car’s exclusive origins.

Virtually no limits are placed on the individual design of a BMW Alpina. From the paintwork to the interior trims and the colour of the upholstery – everything offered by the extensive BMW and Alpina equipment range is available. Seldom does a BMW Alpina leave the plant in Buchloe without making use of the virtually limitless personalisation options offered by the Alpina factory. Our philosophy dictates that the customer can design his or her own entirely individual interior – assembled by skilled craftsmen in our leather workshop.

The new BMW Alpina B4 Bi-Turbo Coupé will reach showrooms in May 2014. Pricing, standard equipment levels and the availability of all-wheel drive may vary depending on country. For further details please contact the authorised local Alpina representative or Alpina headquarters in Germany.