(Most of) the following is from BMW Aero Engines by Jakobs, Kroschel, and Pierer (2009). Please note some of the info below differs from what rinkol reported. I have no idea which source is correct, but I do find it suspect how an engine can produce 400 hp at 1,000 rpm and 530 hp at 1,100 rpm—an increase of 130 hp for just 100 rpm. In general, all the presented BMW VIII rpm data appears low. Perhaps it is really propeller speed and the engine speed is twice what is listed. Again, the data is from the book.
BMW VIIa
First run in 1928, the BMW VIIa was basically a geared V-12 using the BMW Va (straight-six) cylinders. The crankcase was offered in aluminum or Elektron. The engine had a bore of 160 mm (6.30 in) and a stroke of 190 mm (7.48 in). Total displacement was 45.8 L (2,797 cu in). The engine had individual cylinders with two exposed valves per cylinder. The valves were actuated by an overhead camshaft. Three different compression ratios were offered, 5.5:1, 6.0:1, and 7.3:1. The 5.5:1 engine had a normal output of 600 hp at 1,565 rpm. The 6.0:1 engine had a maximum output of 750 hp at 1,650 rpm. The engine was 2.025 m (79.7 in) long, .864 m (34.0 in) wide, 1.045 m (41.1 in) tall, and weighed 525 kg (1,160 lb). The BMW VIIa passed government tests in June 1930. The engine was installed in early, single-engine Junkers Ju 52 aircraft and also the sole Dornier Do J IIb Bos Wal (D-2053), which Wolfgang von Gronau flew around the world in 1932. Only a small number of engines were made.
BMW VIII
The BMW VII was a geared, straight-six engine developed at the same time as the VIIa. The engine had a bore of 160 mm (6.30 in) and a stroke of 190 mm (7.48 in). Total displacement was 22.9 L (1,399 cu in). The engine had individual cylinders with four valves per cylinder. The valves were enclosed and actuated by an overhead camshaft. Three different compression ratios were offered:
5.5:1 – normal output of 400 hp at 1,040 rpm and max output of 470 hp at 1,100 rpm.
6.0:1 – normal output of 400 hp at 1,025 rpm and max output of 500 hp at 1,100 rpm
7.3:1 – normal output of 400 hp at 1,000 rpm and max output of 530 hp at 1,100 rpm
The engine weighed 365 kg (805 lb). Only test examples were built, and it is doubtful the engine ever flew.