Problem: A PCV system is just a dirty vacuum leak with a purpose, but running a crank vent system is less effective and environmentally unfriendly, and an exhaust evac system requires a straight pipe. To solve this, another vacuum source could be used that vents to atmosphere, but with a filtered catch can in place to prevent unburned hydrocarbons from escaping.
Proposed solution: Using the exhaust tip as a vacuum source. I once saw a documentary that showd a car vacuum from the 30s that used an exhaust tip attachment as the vacuum source. I'm hoping to get suction from a similar setup that will replace the engine intake as a vacuum source.
Think it will work? I wouldn't expect any power loss, and this should give a reliable vacuum source without any complicated contraptions like pulley-driven vacuum pumps. If the vacuum is sufficient it should give nearly the environmental cleanliness and active ventilation of a PCV with the gunklessness of a crank vent.
Placed after the cat's w/a catch can like you described.?
I have heard these can produce too much vacuum and actually suck the oil out if you use alternate block venting locations, the ones I have seen used successfully have a restrictor placed inline to reduce the high vacuum. Great for large cams or boosted engines however.
Some vehicles DO have these "pcv"-exhaust vacuum driven systems from the factory, I would assume the reason they are not common is because of the introduction of oil vapors into the exhaust and the added emissions. If the oil vapor is introduced into the combustion cycle, most of it will be burned off. I could not imagine a modern car built with a catch can that you would have to periodically empty yourself.
It's called an eductor. Very common for various applications like water pumps and such.
It's got no environmental benefit over the catch can and overboard dump tubes of early cars through the 60's.
To make it work you've got to place a restriction in the tailipe, creating a low pressure spot (that old Bernoulli's Theorum thing) to port to.
