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good dialogue, as i've had the same ideas kicking around in my head. i also *think* i understand the function of the aos - to vent any gases from the crankcase back into the intake for emissions purposes and to reduce oil aeration. the aos tries to pull out any oil that might be sloshing around and want to put itself into the intake. some questions, however:
- while the air introduced by the aos is downstream of the dme, the dme would also read the air/fuel mixture at the exhaust and adapt, so i'm uncertain if removing the additional air provided by the aos has any negative effect.
- lindsey racing also notes that the air introduced by the aos is laced with oil vapour which is non-combustible, so is actually a detriment to performance. at a minimum, it is not a participant in the combustion process, and removal would result in a lean condition (until the DME adapts) as additional air that can participate in combustion fills the void.
- i can see how vacuum would reduce aeration of the oil, but am uncertain re sealing of piston rings? would sealing of piston rings not best be achived by equal pressure on both sides?
from the above perspectives, you have to weigh the increases performance of not introducing crankcase vapours into the intake against the decreased cooling of frothy oil caused by lack of vacuum. then factor in the potential catastrophy of aos failure.
some half measures include a catch tank that vents to atmostphere; it reduces pressure in the crankcase but does not create vacuum. it does not have a 'seperator' but catches any splashed oil and has to be emptied occasionally. both canton racing products and lindsey racing sell catch cans.
another option i've seen is a closed catch system. it's a tank between the aos and the intake that catches any oil should the aos fail. i've seen them fabricated from a small tank and some wire mesh that serves to stop the oil while passing the vapour. a form of failsafe is all it really is.
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