BMW Alpina B5

(from Alpina Press Release) THE BMW ALPINA B5
ALPINA presented the BMW ALPINA B5 at the Geneva Salon in march 2005, an automobile with 500 horsepower, maximum torque of 700 Newton metres and a top speed of 314km/h – the fastest production saloon in the world. Yet power isn’t the sole defining characteristic of even this BMW ALPINA, an automobile which enriches Buchloe’s gourmet offering in both Touring and Saloon form.

In the end, the key isn’t absolute horsepower, but the manner in which this performance unfolds. In this point, the youngest member of the ALPINA family takes a position at the head of the class – just as its predecessors in ALPINA history. The legendary B10 Bi-Turbo, for example, is a car that enjoys cult status today

In principle, the B5 uses the same powerplant found in the familiar BMW ALPINA B7, with its eight cylinders and 4.4 litre displacement. The engine’s forced induction differs from conventional solutions: it is neither turbo, nor of the type of super-chargers that drain a great deal of power from an engine, especially at higher rpm

A radial or ”Nautilus-type” compressor delivers the ALPINA V8’s boost pressure: one might see it as a combination of super-charger and turbo-charger. It isn’t propelled by exhaust gases, as a turbo would be, but rather belt-driven from the crankshaft. The inner workings of the radial compressor compare to the intake side of a turbo: a small turbine generates up to 0.8 atmospheres of boost to the cylinders. Before reaching the engine, the air passes through a generously-dimensioned inter-cooler, capable of sinking intake air temperature up to 70°C

The advantages of this innovative technical solution? The radial compressor never stops spinning, with no time lag when power is demanded. Under the types of low to partial loads found in everyday driving, the engine operates as if it were normally aspirated, using the full functionality of Valvetronic (variable valve lift). This is the deciding factor in creating advantageous fuel economy. The compressor is controlled through the use of an ”upstream” throttle plate in the intake system – a development unique to ALPINA, and one that makes the charging of the Valvetronic V8, without the use of a common throttle body, even possible

When looking at the horsepower curve, it’s clear what one may expect from this engine-bay-filling, complex technology. At a modest 2,500rpm one has 200 horsepower with which to play. At 5,500 rpm the maximum 500 horsepower are reached, but the fun doesn’t stop there: the engine maintains 500 horsepower up to maximum revs of 6,000rpm. A very wide power band, therefore, across which the B5 provides immediate, optimum power

The torque curve is even more impressive. The curve takes on the form of a massive table mountain. At a mere 1,000rpm, just above idle, the V8 puts out 300 Newton metres of torque. Between 4,250rpm and 5,250, there’s a constant 700 Newton metres of twist on tap

The engine characteristics, as evidenced by the above numbers, are those a of far larger, naturally-aspirated engine. The B5’s powerplant distinguishes itself by instantaneous reactions to throttle inputs, care-free revving up to maximum revs, and a nearly inexhaustible supply of acceleration across the rev range. At fullsong, the BMW ALPINA B5 needs but 4.7 seconds to reach 100km/h (Touring: 4.8 seconds), placing it in the fine company of the world’s most renowned sports cars

Taking advantage of the enormous power requires no high driving art. Stepping on the pedal is enough, as the BMW ALPINA B5 possesses a ZF six-speed automatic transmission with torque converter, known for its especially smooth shifts and quick response

The driver may operate the transmission in Drive mode, letting the automatic do the shifting, or may manually select the gear desired. ALPINA developed SWITCH-TRONIC many years ago for just this purpose. Two buttons on the back side of the steering wheel make removing one’s hands from the wheel when shifting redundant. The right button shifts up, the left button down – enriching the driving experience, and difficult to describe in words

While manual mode is ideal for driving assertively through a series of bends, or on winding roads, it can also help conserve fuel. One may simply command the transmission to remain in gears higher than what the electronic transmission control would select at a given speed. The result: extremely low revs, lower fuel consumption – and even when driving in a such a gentle manner, no one will ever need complain about a lack of torque

When reviewing deceleration times from 200km/h, the B5’s documents its braking capability in imposing manner: less than 5.5 seconds to a full stop. Drawing upon the B7’s braking system, special attention is again placed on comfort under braking. For this reason, the brake discs of 374/36mm front and 370/24mm rear dimension are not cross-drilled. Wet braking performance is enhanced in spite of this by the use of a so-called ”brake-drying” function. From time to time, without the driver ever feeling it, the brake pads are automatically and lightly dragged across the rotors, removing any layer of water – and this only when the wipers are active. Along with TEVES’ two-piston, floating brake callipers, extremely strong deceleration and the best possible reliability are guaranteed

In the wind tunnel, extensive aerodynamic development, testing and attention to detail are the prerequisites for an automobile’s safe driving characteristics - even at speeds exceeding 300km/h. The results are convincing: front and rear lift values are minimal, thanks to the ALPINA aerodynamics package. And despite the sizeable wheel/tyre combination, an exceptional 0.29 coefficient of drag has been achieved

By coupling the B5’s extremely powerful engine with the comfort of an automatic, ALPINA place the Saloon and Touring in a unique position in the high-performance segment. This superior performance brilliantly complements a suspension that is itself an amalgam of sporty handling precision and comfort that is anything but matter-of-fact in high-performance automobiles. The inter-play of struts and springs, together with the MICHELIN Pilot Sport 2 tyres (front, 245/40 ZR 19; rear 275/35 ZR 19), communicate a distinct sense of safety to the driver at every speed, all while simultaneously fulfilling the comfort demands placed on today’s luxury automobile. All very much in the tradition of the house of ALPINA – a concept honed to perfection through attention to detail

This is also true of the extensive standard equipment, with only a few additional-cost extras. Traditional ALPINA high-quality wood and hand-stitched leather interiors, in typical ALPINA Identity, communicate a warm ambience

The BMW ALPINA B5 is a synthesis of uppermost performance and cultured driving behaviour.

© Source: article on seriouswheels.com
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