Quote:
Originally Posted by JFP in PA
It DOES matter, without the five inches of crankcase vacuum, the low tension piston rings will not seal properly, leading to loss of power, blow by into the crank case, etc. I can see adding a puke can between the AOS and the intake vacuum port, but not rerouting the vacuum source elsewhere.
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well, i do understand that porsche uses low tension piston rings, and that they require vacuum to work, but have yet to find a definitive source to confirm the 5" of vacuum value, and also what vacuum is present in the airbox. note that vacuum is present in the intake tract in two ways; at idle with the throttle closed, and as well due to venturi effect as air rushes by. the aos doesnt really want idle vacuum (too high, and vacuum more necessary at higher rpm) however aos returns at that location for emissions reasons.
there is also the more thoughtful perspective: the detrimental effects of blowby vs the detrimental effects (hydrolock) of total aos failure. again noting unless a catchcan can hold a substantial % of the 9 litres of oil in the engine then your 2.5/2.5/2.7/3.2 litre engine is still at risk.