[Christ]

Originally Posted by Kevin Johnson

I get to hear about these problems all the time. Catch cans are not all created equal, that's for sure. Oil separators are easily overwhelmed by foamed oil -- this includes dry sump tanks if the system is not designed with enough reserve. Vacuum relief valves obviate the need for the Mad Max clutch -- though that would be cool. Make sure the relief valves draw in filtered air. Try to draw the vacuum from a properly baffled port in the block versus the valve covers. This is not always practical, of course.

I don't like the idea of drawing vacuum from the valve covers, because if you get enough air moving, it could work against the oil flow dropping back into the block, causing oiling issues and changing the center of gravity of the vehicle (allbeit not by much) as a whole, in upright applications.

I'd rather draw the crankcase vacuum from two vents, one at the back end, one at the front end, both at the highest possible point that would provide the largest distance between the vents and the oil. The vacuum ports in the block should have either wet filters or screens on them to help prevent liquid oil flow, or at least help to vaporize whatever does get out, so the catch cans and separators have a better chance of doing their job effectively.

Anyone know how to get/make dual sided seals? So that you can hold oil in and still hold air out?