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Old 07-12-2023, 07:41 AM   #6
The Radium King
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Join Date: Apr 2010
Location: Canada
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are there multiple mechanisms that induce bore scoring? i understand the concept of lateral thrust on piston walls due to the overboring and longer stroke used to increase displacement. in these cases the lateral force would be greatest at the bottom of the stroke. and also why scoring typically presents in the higher displacement m96/m97 variants.

but what about cylinders going out of round due to high temps/oil failure?

https://www.rpmspecialistcars.co.uk/porsche-bore-scoring/

presume less common as this would be an o&m issue vs design issue, but might be the cause of scoring on the lower displacement boxster engines? in this case the scoring would happen where the out of round is the highest which would be top of cylinder where oil distribution was lowest/heating the highest?
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