Originally Posted by
MaRoFreK 
Whats the function of a catch can? Might be a stupid question but i have no idea.
[SSMike]If you do a search you'll find quite a bit of information on catch cans. Basically it goes in line with the PCV system to condense out any oil vapor before it enters the intake manifold. The condensed oil fills the can and you can periodically drain it out. This improves performance under WOT conditions because no oil will mix into the combustion chambers. Therefore it reduces spark knock and keeps the internals cleaner! Hope this helps.
Hope this helps man i was asking the same thing.