Some people seal the engine up with a PCV installed. This keeps the entire engine close to the same pressure, as manifold vacuum. Some newer EFI setups do this to eliminate the constant leak of unmeasured air flow into the engine. A long subject that does not apply here.
I have concerns with this idea:
1) Sucking the
oil pan in. I have no idea what the high capacity
oil pans can withstand.
2) At wide open throttle, is the blow by gasses more than a single PCV can take away?
Pros:
1) The higher the vacuum, the less air is in the engine, thus less energy is lost spinning air and
oil droplets.
2) The engine cannot leak oil out, when it is under vacuum.
I suppose you could install more than one PCV. Alternatively, put a check valve to a vent, so that air cannot be sucked into the engine, but excess blow by can be vented out.
I know this is done many ways around racing. I have heard of exhaust venturies used to evacuate the crankcase, and vacuum pumps. Also dry sump systems typically run under vacuum.