Four factory 906s received an air-cooled eight-cylinder boxer engine of the type 771, which was already used in the 904/8. The engine had a displacement of 2.2 liters with a compression of 10.2: 1 and vertical shafts that drove the two overhead camshafts per cylinder bank. The maximum output was 198 kW (270 hp) at 8600 rpm. The 906/8 had a five-speed manual transmission of the type 906 and a ZF limited-slip differential . The gear ratios could be exchanged as required without removing the gear.
The 906/8 Coupe was created because Porsche believe the installation of the advanced eight cylinder engines in the chassis with hopes of creating an overall winner at Targa Florio and the Nürburgring. The bore was increased slightly to create a displacement of 2.2 litres, which was good for around 270 bhp.
Four chassis were fitted with this revised unit, but did not attain the successes hoped for.