13th March 2005 – Alpina present the new B5 at the Geneva Salon, 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 this 3 series, more the manner in which this performance unfolds. In this regard, the youngest member of the Alpina family takes a leading position in its class.
In principle, the B5 uses the same powerplant found in the familiar Alpina B7, with its 4.4 liter V8. 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. Instead, a radial or ‘Nautilus-type’ compressor delivers the boost pressure: one might see it as a combination of super-charger and turbo-charger.
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. 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 varibale timing 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 equipment. At a modest 2,500rpm the driver has 200 horsepower with which to play. At 5,500 rpm, the maximum 500 horsepower is reached, but the fun doesn’t stop there, the engine maintains 500 horsepower up to 6,000rpm. The torque curve is even more impressive. 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 of a far larger than those of an equal-sized 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 full song, the B5 needs but 4.7 seconds to reach 100km/h (Touring: 4.9 seconds), placing it in the fine company of the world’s most renowned sports cars
The 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 with two buttons on the back side of the steering wheel. ALPINA developed Switch-Tronic many years ago for just this purpose.
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 Teve’s 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 driving characteristics. The results are convincing: front and rear lift values are minimal, thanks to the new aerodynamics package. And despite the sizeable wheel/tyre combination, an exceptional 0.29 coefficient of drag has been achieved.
This B5’s performance complements a suspension that is itself an amalgam of sporty handling precision and comfort. 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 very much in the tradition in the house of Alpina, extensive standard equipment comes with every car, with only a few additional options usually reserved for the intrior. Thus, an Alpina high-quality wood and hand-stitched leather interiors can be ordered with the B5.
Story by BMW Alpina
Nautilus-type Supercharger w/Air to Ait Intercooler