stupid question from newbi

The PCV valve has a lot of blow by, so the catch can resolves this.

 

All that blowby that goes through the PCV valve gets routed into your intake and puddles up in the intake...it also gunks up the the ports inside the intake, the heads and can be seen on the piston crowns. I've seen this first hand when my motor was apart recently. I would highly suggest the catch can to anyone who wants to keep the insides of their motor as clean as possible.

 

Here you go.

The PCV (Positive Crankcase Ventilation) system vents gasses and vapors into your intake manifold. The hot (agitated) oil in the oil pan/crank case gives off some not so emissions friendly gasses. Used to be that your engine just had a rubber tube coming out of the side of it and pointed down towards the road. Then emissions and catalytic converters happened and they figured this wasn't such a good idea. The idea here is to run the gasses and vapors back into the intake manifold where they get burned in the engine. Whatever makes it through the combustion is taken care of by the catalytic converters.

So the vacuum in the intake manifold sucks air from the crankcase. The "intake" air comes in from over on the other side of the engine by the oil filler tube (that's that tube that runs into the side of your cold air intake). The PCV valve works as a one way valve and also regulates the max suction/flow.

Some engines, like ours and the LS engines, seem to have a tendency to produce more oil vapor and droplets through the PCV valve than others. With ours it's likely that the oil squirters produce some atomized oil that floats around, etc. This oil gets sucked through the PCV valve and ends up condensing in your intake manifold, eventually getting sucked (in small amounts) into the cylinders. It's probably not going to effect basic function or longevity of your engine but it's noticeable when you're looking for peak performance. The PCM has to apply more knock retard, it's not as consistent, etc.

An PVC oil catch can is put inline between the PCV valve and the intake manifold. A proper catch can will have the following:
- Air flow through the can should go down and change direction (back up) somewhere. Larger (still very tiny) droplets won't make the bend.
- Air flow, should slow as it moves through the can. Provides more time for it to cool and condensation to take place. For example it comes in through a 1/2" pipe or fitting, into a chamber that's maybe 2 to 3 inches across and then back out a 1/2" fitting.
- Air flow on the way out should go through some sort of filtration material like stainless steel wool. This provides a lot more surface area for condensation to take place on.
- The "trap" or collection area in the bottom of the can should have something to inhibit or prevent the trapped oil from splashing or creeping up the side of the can in aggressive maneuvers so that liquid oil does not splash or get sucked out the outlet fitting. Usually there are stepped ridges on the walls or a funnel/cone at the top of the collection area, etc.

It's pretty common for the 6.1L's to have a white puff of smoke on startup. People also see a lot of knock retard with predators (and stock). Most often both are eliminated or decreased significantly with the addition of a PVC catch can.

how's that?

 

Nice one Dave!!! My response was just a very short summary of this:worthy:. It was disheartening to see when I bought my used P&P heads that there was oil residue on the insides of the intake and exhaust ports and on the tops of the valves too. I had that all cleaned, but man, I wouldn't run my car without a catch can after seeing that.:shok:

 

This is without a catch can.



This is with a catch can.



This is the can.

 

Pretty simple actually. I have the McKinney. Most everybody else has the Billet Technologies catch can (our featured vendor this month). More bling, comes with hoses, and you don't need to make a bracket.

 

lol And BT has a nice discount going on...