VAD

"If you choose to run vacuum in a wet sump system there are other areas to take note. The oil pump type, pan volume, and pickup location are even more critical under these circumstances. Since you are applying vacuum to the crankcase itself, you would actually be working against the oil pump. In essence, both pumps are applying a type of suction to the same area of the engine. The vacuum pump is trying to draw air, and the oil pump is trying to draw engine oil. Inevitably, this will cause the oil pump to work harder, operate at lower pressure or even cavitate, which could be detrimental to the longevity of your engine."

You're playing with fire. I'll say this again: Vent to atmosphere and be done with it. Is it possible to benefit the engine by applying crankcase vacuum? Absolutely, but you better be damn sure of what you're doing.

http://www.onedirt.com/tech-stories/...d-air-control/