B4 Bi-Turbo Coupé and Convertible replaced by upgraded S, combining long-distance comfort with astonishing performance
Nottingham (UK). Luxury vehicle manufacturer ALPINA will launch its new B4 S Bi-Turbo at the London Motor Show (May 4 – 7) following the model’s international preview at the Geneva show in March. With two new ALPINA-specific turbochargers and an uprated cooling system, power climbs from the previous model’s 410 bhp to 434 bhp and torque leaps from 442 lb ft (600 Nm) to an astonishing 487 lb ft (660 Nm), giving the luxury four seater a top speed of 190 mph and acceleration that will take it to 60 mph in just 3.9 seconds.
“The S designation is reserved for the highest performance ALPINAs, most of which have been manufactured in very small numbers,” explains ALPINA GB general manager Gary Lott. “Think of the B7 S saloons and coupés, the legendary B10 V8 S and the E46 B3 S, whose hand-assembled 3.4 litre straight six is considered by many to be one of the greatest engines ever made.”
The new B4 S Bi-Turbo, available as Coupé and Convertible, provides a unique combination of comfort, refinement and very high performance that is a hallmark of ALPINA’s extensive engineering development. “ALPINA customers value the finely-honed feel of a bespoke car and the easily accessible performance that comes with substantial torque,” Lott continues. “An ALPINA is often described as ‘the best performance car for the real world’ and that’s something we are very proud of.”
Based on BMW’s latest generation 4-Series, the B4 S Bi-Turbo is the result of a two year development programme during which every aspect of the vehicle was analysed and refined to increase performance, comfort, efficiency and style compared with the standard 4-Series. Using design and validation processes identical to those implemented by BMW, ALPINA’s team of 70 engineers worked with specialist suppliers to enhance the engine, gearbox, cooling system, body structure, wheels, tyres, aerodynamics, steering, suspension and interior.
At the heart of the new B4 S Bi-Turbo is an extensively re-engineered version of BMW’s highly-regarded 3.0 litre straight six, built around a specially cast, reinforced crankcase. For the previous B4 Bi-Turbo, ALPINA engineers replaced the standard engine’s twin-scroll single turbocharger with a twin-turbo system, complemented by optimised induction airflow, a forged steel crankshaft and an uprated cooling system. For the S, ALPINA has specified a new, bespoke twin-turbo system that provides even higher capacity with a further evolution of the free-flow induction system to allow near-instantaneous response to throttle demand. The S engine also has a new piston crown cooling system and a bespoke thermal management system that ensures temperature stability over prolonged, fast driving. With more than 442 lb ft (600 Nm) available from 2000 rpm to 5000 rpm, a 7,000 rpm limit and exceptional durability, the result is a bespoke powertrain that delivers very high performance, effortlessly over great distances.
The S also receives higher spring and damper rates and subtle enhancements to the aerodynamics including a revised front spoiler and rear apron. The cooling system has been further uprated to ensure consistent performance and long-term durability with the additional ALPINA water radiator and external oil cooler now 15 % and 35 % larger respectively, compared with those fitted to the B4 Bi-Turbo.
The gearbox is ZF’s excellent 8-speed, with 20% of the components optimised specifically for ALPINA to ensure very smooth changes even in Sport mode. The S now has a limited slip differential fitted as standard on UK-specification cars, optimised to ALPINA specifications to provide a very progressive lock up to 40%. High-strength drive shafts are specified to accommodate the engine’s exceptional torque. The ALPINA brake system, with distinctive blue callipers (four pot front), has a fixed calliper architecture to improve feel and responsiveness.
With four elliptical outlets, the Akrapovic exhaust, designed to complement the revised engine, delivers a powerful yet refined sound quality, with a sports setting that can be manually or automatically selected.
The ALPINA B4 S Bi-Turbo is available in the UK as a Coupé for £63,000 or as a Convertible for £67,000, with a long list of standard equipment chosen for comfort and driving pleasure over long distances, including LED front lights with High Beam Assist, heated sports seats with electric adjustment and BMW Professional media package with navigation. Every ALPINA is also fitted with discreet ALPINA luxuries, crafted in high-quality materials.
The luxury carpet overmats, seatbacks, door treads and front spoiler include subtle ALPINA branding. Wheels are the famous ALPINA Classic design with a 20” diameter and bespoke tyres, the instruments are in ALPINA Blue and the sports steering wheel is covered in finest-quality, hand-stitched Lavalina leather. Every car is finished with a model plaque displayed on the centre console, showing the car’s unique build number.
In addition to being available with all BMW options including those from BMW Individual, the B4 S Bi-Turbo can receive almost limitless personalisation from ALPINA’s craftsmen. Alongside the famous ALPINA Blue and ALPINA Green signature paintwork, choices include hand-stitched full leather interiors of superb quality and a wide range of hand-finished woods for the dashboard and doors. The iconic ALPINA Deco Set, which includes front and side stripes with the ALPINA logo, makes a welcome return as standard equipment with a zero cost delete option.
The equivalent B3 S Saloon and Touring will join the B4 S Bi-Turbo Coupé and Convertible around mid-year. Four Wheel Drive versions of each model are available in left hand drive markets.
ALPINA has worked closely with BMW for more than fifty years, building the trust in engineering excellence that allows shared warranty cover and high levels of collaboration. The company was registered as an automobile manufacturer in 1983. ALPINAs can be serviced at any BMW dealer.
For more information on ALPINA’s extensive engineering of this model, please see the following technical notes.
50 years of bespoke cars
ALPINA Burkard Bovensiepen KG was established on the 1st of January 1965 in Kaufbeuren. Two years later it adopted the now-famouse badge featuring a twin-choke downdraught carburettor and a crankshaft on a shield; a proud symbol of the company’s dedication to superb engineering.
Although today the company is focussed on exceptional road cars, its ethos has been formed by decades of racing success with a driver roster that includes Derek Bell, James Hunt, Jacky Ickx, Niki Lauda, Brian Muir and Hans Stuck. Throughout this time, the close relationship with BMW was developing, with factory support for road car development and collaboration in motorsport that included commissioning ALPINA to develop the light weight race car that became the legendary BMW 3.0 CSL.
Today, ALPINA is one of the world’s leading manufacturers of high-performance luxury automobiles, selling on every continent yet still in numbers small enough to allow each car to be bespoke. Production is around 1,700 per year and there are currently no plans for significant growth beyond this. Fewer than 100 cars are sold new in the UK each year, while interest in models is growing rapidly alongside their values as enthusiasts recognise the considerable pleasure of driving a classic ALPINA.
“ALPINA is a company that creates subtly stylish, very high performance cars that can be tailored to each customer’s personal requirements, yet offer the long-term comfort and durability required for daily use,” comments CEO Andreas Bovensiepen, son of the company’s founder Burkard Bovensiepen. “We have a unique philosophy and a commitment to engineering excellence that we intend to maintain and build on across the next 50 years.”
Richard Gotch at Market Engineering
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Images and notes on engineering the B4 S Bi-Turbo follow
The new ALPINA B4 S Bi-Turbo can be specified as a Coupe or a Convertible
These cars are in the signature ALPINA Blue
The new ALPINA B4 S Bi-Turbo Convertible
The new ALPINA B4 S Bi-Turbo Coupe
Bespoke aerodynamics enhance safety and stability at very high speeds
Extensively re-engineered for very high performance with driveability
and durability over long distances, ALPINA’s Bi-Turbo 3.0 litre straight
six now delivers 434 bhp and an astonishing 487 lb ft (660 Nm)
Engineering the B4 S Bi-Turbo
ALPINA CEO Andreas Bovensiepen says the remarkable combination of comfort, performance and durability achieved with every vehicle is possible because although all BMW ALPINAs are available with an almost infinite variety of bespoke luxuries, his company manufactures only one mechanical specification for each model.
“As well as enhancing the performance of all major vehicle systems, our engineers are able to focus on ensuring that they work perfectly together, without the compromises needed for wide model and option variations,” he explains. “For ride comfort, for example, there is one combination of seat cushion, tyres, wheels, dampers, bushes and springs, so they can be designed to work as a well-coordinated team. Also, we build only 1,700 cars a year, so we can do things that would not be possible in volume production.”
Based on BMW’s highly-regarded N55 straight six, the B4 S Bi-Turbo engine is extensively re-engineered to provide effortless, very high performance with excellent long-term durability.
ALPINA’s engine is built around a bespoke aluminium block with Bi-Turbo flanges that allow the mounting of two turbochargers (one very small for ultra-fast response, one larger for high boost levels) along with the necessary oil and water connections and a close-coupled catalytic converter. ALPINA-specification sparkplugs and a bespoke high-strength steel crankshaft help ensure exceptional durability.
The turbochargers are fed from larger intake ducts with optimised radii, allowing the engine to breathe more freely by reducing induction air pressure losses by up to 30 percent compared with the standard system. The result of complex fluid dynamics modelling, the bespoke induction system allows increased engine output as well as improved throttle response. A larger intercooler with flow-optimised aluminium ducting increases the density of the fuel / air mixture to further enhance engine performance.
An additional radiator in the engine cooling circuit is mounted behind the bespoke front spoiler, which also directs air to the new, high-flow oil cooler. Control is provided by a dedicated thermal systems control unit that uses information from the vehicle’s databus to optimise powertrain temperatures and to reduce parasitic loading on the engine by momentarily switching off the fan when maximum acceleration is required.
“One of the biggest challenges is finding space for the additional systems and especially for the larger diameter induction system with reduced radius curves,” explains ALPINA GB’s Gary Lott. “One of the benefits of ALPINA’s substantial investments in Computer Aided Engineering is that every inch of space can be identified and used to increase performance, throttle response and durability.”
ALPINA has paid equal attention to the hot side of the engine. The bespoke, free-flow exhaust manifold is manufactured from high carbon steel with a cobalt addition to provide very high temperature resistance. The light-weight, quad-outlet exhaust system, developed with specialist supplier Akrapovic, is optimised for gas flow as well as for acoustic characteristics, which are enhanced by opening a computer-controlled valve when the Drive Performance Control is in Sport mode and when the system identifies spirited driving. The Akrapovic system is 7.5 kg lighter than the standard BMW system.
The eight-speed transmission has been developed in partnership with ZF to provide a very fast shift speed while ensuring durability with the B4 S Bi-Turbo’s immense torque. Around 20 percent of the unit’s components have received design changes. Linked to recalibrated software, the system provides smooth, comfortable gear changes with no noticeable interruption to power delivery.
The high torque delivery over such a wide speed range allows the use of a long rear axle ratio which in combination with the Eight-Speed Sport Automatic Transmission and Auto Start Stop contributes significantly to achieving exceptional fuel economy. The driveshafts and differential are also reinforced and a limited slip differential is available as an option.
Ride and Handling
The combination of incredible performance and low emissions is matched by a remarkable ride quality and superb dynamics. Bespoke ALPINA springs with a 40 percent higher rate work with bespoke roll-control bars, bushings and bump stops. The four-setting variable damper control has been recalibrated to provide softer compression and stiffer rebound. The system works with the revised springs and bushes to provide superb body control, particularly in the sports settings, while allowing excellent bump absorption. Front camber and toe-in are optimised and a front body strengthening brace, designed specifically for this model, is fitted to further enhance steering feel, turn-in and dynamic consistency.
Wheels are ALPINA’s legendary ‘Classic’ design with a 20” diameter, carrying non-run-flat Michelin Pilot Sport S tyres optimised for this vehicle. Enhanced tread stability and flank reinforcement reduce temperature spikes during very hard driving, ensuring consistently excellent grip in the dry complemented by a bi-compound running surface to ensure equally outstanding performance in the wet. Side walls that are 20 percent softer contribute to the car’s superb ride quality and refinement.
Brembo callipers in ALPINA Blue announce a bespoke braking system with 370 mm discs and four piston callipers at the front and 345 mm discs with twin piston callipers at the rear. The pad specification has been selected to provide excellent temperature stability to provide consistently good stopping performance and pedal feel during hard use, without compromising feel or refinement when being driven more gently.
To help ensure that every aspect of the suspension works perfectly together, ALPINA has recalibrated the control software for the power steering, the Dynamic Stability Control and the Dynamic Traction Control. “This is a great example of the attention to detail that is applied to optimise the entire car as a unified driving system,” says Bovensiepen. “Optimising the DSC for our wheel and tyre combination means that we can deliver more performance and greater safety, with unobtrusive intervention helping to make the vehicle feel wonderfully neutral at its dynamic limits.”
The appearance of a BMW ALPINA has always been a distinctive blend of function and style. For the S, the car has returned to the BMW wind tunnel for further refinement to ensure stability and a low drag coefficient at very high speeds. The larger inlets of the new front spoiler provide the necessary airflow to the front brakes and through the additional heat exchangers and also work with the bespoke rear spoiler to reduce high-speed lift to within two decimal places of zero.