Alpina B10 Biturbo

Production period:	1989 to 1994
Class :	sports car
Body versions :	saloon
Engines:	Petrol 3.4 liters (257–265 kW)
Length:	4718 mm
Width:	1750 mm
Height:	1397 mm
Wheelbase :	2760 mm
Empty weight :	1695 kg

The Alpina B10 Biturbo (spelling: Alpina B10 BiTurbo ) was a sports sedan built in small series from the car manufacturer Alpina . From September 1989 to March 1994, 507 units were built, all of which - as is usual at Alpina - were given a consecutive production number. This was hammered into the right shock absorber dome, and a silver-plated nameplate with the production number was also attached to the center console in the interior.

It was based on the BMW 535i (E34), whose inline six -cylinder engine was charged with 2 water-cooled Garrett T25 turbochargers in a parallel arrangement . The water-cooled shaft bearings on both loaders made it possible to largely prevent the oil lines from coking. In addition, a second, electrically driven water pump was installed, which continued to run for about 10 minutes after the engine was switched off. According to Alpina nomenclature, the engine was called B7 / 5, which was also the trade name for the B10 Biturbo. The use of two turbochargers arranged in parallel was a new feature at Alpina and ensured that the engine responded faster and more evenly and prevented turbo lag. The charge pressure regulation was controlled by the driver himself using a potentiometer. The maximum power was available at 0.8 bar overpressure, the adjustment range was between 0.4 and 0.8 bar boost pressure. Furthermore, an air / charge air cooler was flanged in front of the water cooler. A crankshaft with seven bearings was also part of the scope of work, as were special cast pistons with squeeze edges and piston crown cooling from Mahle GmbH , which reduced the compression to 7.2: 1. In addition, special, artificially aged rocker arms were installed; this measure achieved a higher strength of the material and ultimately a stable engine. Through the measures described, the performance of the M30B35-Motor increased from 155 kW (211 PS) to 265 kW (360 PS), the maximum torque from the standard 305 Nm to 520 Nm.

The exhaust system consisted of a double-flow exhaust pipe, each line contained three Emicat catalytic converters with 100 cells (CH version 200 cells), wound from 40 µm thick coated stainless steel sheet. This design enabled a very large cleaning area in a small space with little exhaust back pressure. The catalyst volume roughly corresponded to that of the cubic capacity. Alpina was the first manufacturer to use metal catalysts.

The Getrag 5-speed gearbox type 290 was a gearbox specially manufactured for the biturbo in order to be able to transmit the high torque of the engine. The cardan shaft got a reinforced center bearing from the M5 .

The rear axle with 25% lock was from the BMW M5. In addition, a rear axle cooling was installed at Alpina, the first 255 vehicles had a mechanical oil feed pump, this was driven via the right drive shaft by means of a V-belt. An electric pump was used from production numbers 256 to 507. This cooling was thermostatically controlled and had the advantage that the oil was not permanently cooled at low outside temperatures, and it was also less prone to failure. The cooling coil was located in the rear between the rear cover plate and the bumper.

In the interior, alpine-specific wood applications were installed on the dashboard, the center console and the door panels. Sports seats, a sports steering wheel and a wooden gear knob were also part of the scope of equipment, as were the additional digital instruments for engine oil temperature, engine oil pressure, rear axle oil temperature and boost pressure display. A 30 liter additional tank was installed in the trunk, which increased the fuel supply to a total of 110 liters.

The exterior included 20-spoke aluminum wheels in Alpine design, 8.5 × 17 "at the front and 9.5 × 17" at the rear. The biturbo had tires with 235/45 ZR17 tires at the front and 265/40 ZR 17 tires at the rear. Furthermore, the B10 had a sports suspension, a standard level control from Fichtel & Sachs at the rear and Bilstein shock absorber inserts, front and rear spoilers and the typical Alpina side decoration in gold or silver on the front axle.

In the last year of production, the equipment was expanded again. The standard equipment included complete water buffalo leather equipment, air conditioning and instruments with a blue background.

When it was launched in 1989, it was considered the most powerful series-production sedan in the world and the fastest German series-production car. The Porsche Turbo only surpassed it in 1995, when it was also equipped with two turbochargers.

As the most powerful production sedan, the B10 Biturbo was surpassed two years later by the Lotus Omega , whose more modern engine with four valves per cylinder and 0.2 liters more displacement with 277 kW (377 hp) made 12 kW more. The fastest production sedan was also surpassed in 1996 by the Brabus E V12 based on the Mercedes-Benz E-Class , which achieved an electronically governed top speed of 330 km / h.