So I have been doing some reading on ways to vent the crank case and run the catch can. From previous threads on this site I can see that everyone seems to be setting their cans up differently. Some just put a filter on the filler neck, some run a hose from the filler neck to a catch can and vent the can to the atmosphere, and others run a closed catch can and route the hose back to the intake. Now I don’t like the idea of running dirty fumes back into the intake manifold, venting to and atmosphere would prevent that from happening. Now correct me if I’m wrong here, but isn’t the best way to vent a crank case is by applying a vacuum to it? By applying a vacuum to the crank case, seals tend to seal better, that’s why drag racers use vacuum pumps on their cars to help make more power. So my question is would it be more beneficial to vent the catch can to atmosphere and keep the intake manifold clean, or should I recycle the fumes back into the intake which will give me some kind of vacuum on the crank case?

 

Mine is under vacuum. Works great.

 

Mine too... I mean under vacuum, but never seen any oil in it. Never seen oil in the intake either.
But I know pressure is build in the crank case so both ways works.

 

Either way would be fine of course. I personally just put the filter on the catch can and vent to the engine bay while plugging the intake side.

 

actually in the strictest of terms the rotary engine does not have a "crankcase".
Its more of a dry sump thing?
And if i am not mistaken the vacuum supplied to the oil pan does nothing to help the rotor seals?
What it DOES do is to help rid the oil supply of a lot of built up moisture (white gunk) that can accumulate in larger quantities than some may realize.
I have vacuum on mine --except when I track.
OD

 

You do make a great point about the rotary being like a dry sump style setup. Your also right about vacuum supplied to the oil pan does nothing to help the rotor seals. But I was referring to the oil seals, side seals and corner seals. This is where the (white gunk) is being produced because of trapped air and the turbulent environment on the sides of the rotors.

 

Anyone have anythig to add???