IN THIS FEATURE Saab reinvents the engine How does SVC work? How does SVC work? What's it like to drive? What next? How SCC works

The monohead is tilted by five rams which resemble normal connecting rods. A shaft - which looks a little like a crankshaft except that all the cranks are on the same side - rotates under hydraulic pressure to move the rams. Changing from high compression to low is faster than the other way round, because cylinder pressures naturally force the monohead further away from the crankshaft.
(pic of end-on view, showing two positions)

1. When running gently, the combustion chamber is small, the compression ratio is high to burn the fuel as efficiently as possible, and the supercharger is disengaged
2. When you need more power, the supercharger clutch engages, the monohead hinges upwards, the compression ratio reduces and the SVC engine can cope with huge boost pressures. The compression ratio runs at whatever gives the best efficiency for the moment, across a range from 8:1 through to 14:1

The supercharger and its intercooler are encapsulated inside the air intake tract. This is to cut down the supercharger's noise, which project leader Lars Bergsten describes as 'tremendous'.