Argentina, altitude and engines.
With the exception of the Safari Rally of Kenya, Argentina is the highest 'regular' round of the World Rally Championship.
On Sunday's final leg, crews will travel west to the Translasierra region and tackle the famous El Condor stage, which starts at 2115 metres above sea level. On legs one and two the average height is still more than 1000 metres.
At an altitude of 1000 metres air is less dense and contains less oxygen that it does at sea level. This affects the amount of fuel that can be burned by any engine and hence the power it can produce.
With the exception of the Safari Rally of Kenya, Argentina is the highest 'regular' round of the World Rally Championship.
On Sunday's final leg, crews will travel west to the Translasierra region and tackle the famous El Condor stage, which starts at 2115 metres above sea level. On legs one and two the average height is still more than 1000 metres.
At an altitude of 1000 metres air is less dense and contains less oxygen that it does at sea level. This affects the amount of fuel that can be burned by any engine and hence the power it can produce.
As an example, in standard specification the Subaru Impreza WRC2002 would be down on power by about 10% at this height...
....however, engineers at the 555 SWRT have modified the engines on the Argentina cars to lessen the detrimental effects of the altitude. To force more air into the engine's inlet system, the turbo speed is increased from a typical 140,000rpm to 160,000rpm.
The 555 SWRT's cars also run a unique engine map, which alters the ignition timing and fuel injection system to maximise combustion.
If this is the worst rally for engine altitude-sickness, then Sweden is the best. Temperatures as low as -20? and stages close to sea level help give the engine the best possible air/fuel mixture.
