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Why is positive crankcase ventilation incorporated into petrol engines?
As the name suggests, there is "positive" pressure in your crankase from all that movement. you could create a vent that just let it out into the atmosphere, but since… it has fumes from oil/gas it's bad for the environment. this is why it is piped back into your intake system and burned off in the engine. -R. Mesyef (MORE)