PCV line.

 

^thanks Fperra, you are like a godfather of turbocharging to me...something like Sideways to the SC folks.

 

Thank goodness you didn't say grandfather.
Make sure that the catch can is a sealed one - no breather allowed.

 

Got my Krank vents yesterday and decided to do a little testing. What I found was the valve on the small unit was much stronger than the big one.

Basically I used a hand pump with a psi gauge, clamps, and a high presser hose. On the small unit I could not force air past the valve at 30psi.

On the big unit however I could induce an air leak starting around 8-10psi.

My guess is the larger unit is not supposed to completely restrict airflow like the small unit is, so it doesn't create too much of a vacuum. From everything I've read, negative 10-20psi is optimal. I had sort of wondered how they would maintain this range.

If anyone else could try a similar test, it would at least let us know if I screwed up the test somewhere

 

The big unit that goes on the front valve cover port never see's positive pressure, so I don't really see the relevance of your test.

 

Its not too difficult, what has everyone been argueing about for the last 5 pages?

The valve blocks air coming into the valve cover (you know that fresh air problem people have been discussing) to create a vacuum. When a neg 10 or so psi builds in the valve cover its going to start drawing air from the front valve cover port, through the krank vent, and through air filter.

Basically fresh air can still enter through the krank vent when certain conditions apply, it does NOT create a 100% block.

The SMALL unit on the other hand does, up 125psi according to the manufacturer.

This resolves the problem of creating TOO much vacuum.

 

He talks about vacuum in the range of 10-20psi and the vent leaking at 10psi...so if you suck or boost, it leaks.

 

I don't buy it. Just because it leaks on positive pressure doesn't mean it will leak with an equivalent vacuum on the other side. There are different flow dynamics involved when dealing with positive pressure on one side vs. vacuum on the other. You have other sources of leaks that prevent too much vacuum. Namely, the blowby gasses past the rings and the rubber spark plug tube seals. In fact, if you just gut the PCV valve such that it is just a hollow tube, the vacuum level increases to the point that you can hear the spark plug tube seals leaking. They make a continuous popping sound at idle that you can hear from the drivers seat.

 

Well I did buy it (the krank vents), installed it yesterday (bot lines) and I know what placebo means but in higher gears the car feel faster, runs more quiet than before and idle is more stable.

And I also got the mother of oil catch thanks, just didn't find a place to put her yet. From Dragon Mall (chinese mall) for an a$$whooping 4.9USD with all fittings. It's an air compressor filter and if you blow into it a few times, water start building up inside..wow

 

Those compressor filter creep me out. One I don't like having glass bowl in my engine, the filters weren't designed for synthetic oils, and 5 micron is way too thin.

I can either one of two things happening to me, either the bowl will break or it will ingest pieces of the filter.