B12 5.0 and 5.7 (E31)
B12 5.0 Alpina introduced a grand touring alternative of the B12 5.0 in 1990, based on the E31 8 Series' 850i and the later 850Ci models. It was introduced a few months after the introduction of the 850i.
Notable mechanical changes include higher compression Mahle pistons fitted to the engine, along with larger intake valves, modified cylinder heads, a new exhaust system, and a modified Bosch Motronic ECU. These modifications allowed the engine to have a power output of 350 hp-metric at 3,500 rpm and 470 Nm of torque at 4,000 rpm. The engine's red-line was increased to 6,400 rpm. The B12 5.0 was only available with a 4-speed ZF 4HP24E automatic transmission. The transmission was modified electronically for improved gear changes. Other mechanical modifications consisted of new springs and Bilstein shock absorbers.
On the exterior, the car was fitted with Alpina 17-inch multi-spoke alloy wheels and a front spoiler with special paint choices along with optional Alpina pinstriping. The interior was customised to the customer specifications and contained a wide range of options, with an Alpina instrument cluster and badging being standard. The cars had special Vehicle Identification Numbers for easier recognition.
Performance figures include a claimed 0-97 kph acceleration time of 6.4 seconds, 0-100 kph acceleration time of 6.8 seconds and a top speed of 174 mph. Only 97 cars were made before the B12 5.0 was succeeded by the B12 5.7 in 1994.[6][2][7]
B12 5.7 The B12 5.7 was originally based on the newly introduced 850CSi. It was introduced to the public in November 1992. The B12 5.7 used the new BMW S70B56 V12 engine with capacity enlarged to 5.7-litres, a modified air intake, camshafts, and a modified crankshaft. The exhaust system used was Alpina designed with stainless steel catalytic converters and the Bosch Motronic engine management system was modified. The engine has a power output of 306 kW and 570 Nm of torque.
The engine is mated to a 6-speed manual transmission made by Getrag. However, an electronic clutch system called Shift-Tronic by the manufacturer was optional. The system was developed in collaboration with LUK GS[8] and the B12 5.7 was the only Alpina model to be offered with that system. 32 cars were equipped with the Shift-Tronic system and had "Shift-Tronic" badging at the rear in addition to the regular badging.[9]
Exterior changes are nominal and similar to the 850CSi. However, a unique carbon fibre bonnet with vents for engine cooling and a central NACA duct was fitted to the car. The interior had anthracite leather upholstery with blue contrast stitching along with an Alpina instrument cluster, wood trim, and a wooden gear knob as standard, but was customisable according to the customer specifications.
Performance figures include a 0-100 km/h acceleration time of 5.8 seconds and a claimed top speed of 300 km/h. Production of the B12 5.7 amounted to 57 units, with the last example built in November 1996.[2][10][7][11]
