No replies yet, so I'll chime in. Mine is for an 87 GN. Different, but the concepts are the same.
First thing is, what are you wanting to do? On a race car, the catch cans collect oil that vents out of the crankcase and valve covers when under load/boost. This is necessary due to blow by past the piston rings and not wanting to blow out seals from excessive pressure in the crankcase. The other purpose is to not dump oil on the track. In this case the catch cans separate the oil and vent the "clean" air out without making a mess.
In my case, it was for a street driven car where I'm wanting to separate oil / vapor from the PCV line before it goes into the top of the intake manifold. I want positive ventilation on the crankcase to pull water vapor out of the crankcase keeping the oil cleaner. The PCV system keeps a slight vacuum on the crankcase to also help keep things sealed up better / less leaks from valve cover gaskets and rear main seal.
I was using the common filter-vents on both valve covers, but I was getting high BLM's at idle caused by the extra air coming in thru these vents. This extra air isn't metered by the MAF so the computer adds fuel at idle thinking it's running lean. I added an air/oil separator catch can in the PCV line and I added another one to the "clean air" make-up to the valve covers. This keeps everything closed up like it was from the factory in 1987 and cleans up the oil vapor that normally goes into the intake.
I recently added this upgrade and it's documented here.
Motion Raceworks 2 Stage Air/Oil Separator?
I'm attaching some sketches I made that may help. Different that a hot air car, but you'll get the idea. I'm a visual learner, so I drew it up to help me arrange things under the hood.
Hope this helps,
John
