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As I recall the Vario cam solenoids actuate at 3000 rpm to phase the cam shafts into the proper position for low rpm operation. The actuators extend tensioning the chains in order to effect rotation of the cam shafts. This increased cam drive chain tension is what accelerates wear of cam drive components.
Above 3000 rpm this tension is relived as the cams change phase for high rpm operation. There are other loads associated with wot but it appears the cam drive is the most dominant point of vulerabilty. Oil film strength on cylinder walls seem to be better at higher rpm.
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986 00S
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