Quote:
Originally Posted by SixBanger
Whats blow-by?
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Combustion gas that slips by the piston rings into the crank case. The piston to cylinder wall is not a perfect seal so it is just a fact of internal combustion engines.
This gas pressurizes the crank case which is why engines have have crank case vents--to evacuate the crank case so it doesn't build up which would have various negative consequences.
Higher torque per liter engines (i.e. turbos) are likely to have more blow-by for various reasons, increasing how much oily blow-by has to be vented, which ends up as the carbon build up on direct injection engines.