The Lost BMW V8 and V12 Engines From the 1970s!

The V8, based on the M10?	V12 neatly fills E23 engine bay.

These pictures were a real find! They are from a BMW sales brochure for the 1982 E23 seven series.

The V8 may have been based on two M10 cylinder blocks and heads. Based on BMW's development of the M10 we could imagine the V8 having possible capacities of 3.0, 3.2, 3.6 and 4.0 litres. The later is perhaps the most likely as it would be a step above the 3.5 litre M30 which was the companies largest engine at the time.

The 3.430 litre M30 straight six produced 218bhp and 229 ft/lb of torque so a 4.0 V8 would have to beat these figures. This might not have proven an easy target. The 2.0 M10 produced 100 bhp / 116 lb/ft in carb form and 130bhp / 131lb/ft in the injected 2002tii so a doubling of these figures doesn't give much advantage for the extra engine complexity, perhaps 10% but who outside BMW can really say.

The V12 was perhaps a more promising proposition. Looking at the photo I'm struck by the similarity of many components to the M30 six cylinder engine (it's worth pointing out the engine seems to have no air flow meter(s?) or air filter in the photo). This would give capacities from 5.0 to 6.9 litres and a possible bore out to 7.4 litres! The smallest 5.0 litre version could be expected to develop around 300bhp and 320lb/ft with a lot of room for development. If based on the M30 iron block this would be a pretty heavy engine.

Of course my assumptions may be wrong (there's always a first time!) and making a V8 isn't a simple as welding two cylinder blocks together and redesigning a few parts. But some of the core properties of BMW engines from the same period can safely be assumed.

So why did they never enter production? The E23 brochure says, "In recognition of future requirements BMW decided, for example, not to introduce large V8 and V12 engines already developed to the production stage, but to replace them by more up to date power units". The preceding paragraphs make statements about fuel consumption and driving conditions. Let's not forget the E23 entered production in the mid-70s when the energy crisis of 1974 was still a strong factor in car design.

BMW did eventually make V engines. In 1987 The M70 5.0 V12 24 valve engine was fitted to the new E32 seven series. Later in 1993 the M60 3.0 and 4.0 V8s were made available in the E32 and the E34 five series, they used four valves per cylinder and an aluminium cylinder block. Details are on the E & M numbers page.