There is another factor which I don't recall being discussed which is compression blow-by the piston rings building pressure in the crankcase. There needs to be sufficient ventilation from the crankcase or pressure will build. I have similar questions on how to structure the crankcase ventilation system. I have a Keithcraft FE stroked crate engine that has a hose from the drivers valve cover to air cleaner carb intake, a puke tank with road draft and connection to the rear intake manifold and crank case and a vented
oil fill cap and I still blew the
oil fill cap off the breather at Fontana this summer. It seems my engine needs more crankcase ventilation area. Any idea how much bypass flow is created by the
oil rings at 4000 RPM, etc? What is a acceptable positive crankcase pressure?