Another Catch Can Thread

[Irace86.2.0]

Originally Posted by tomm.brz

i ask my self why vortech and jackson racing put it in their SC kit but hks doesn t.. what can happeb if crankcase pressurize?

The whole reason behind the PCV is to vent that pressure otherwise air pressure would build to such levels that stuff would happen like gaskets failing, pistons finding resistance moving down, maybe oil pressure at the pickup spiking, catastphic engine failure, etc.

Maybe they don’t include it because they figure the time on boost isn’t enough time to cause concern. Maybe they didn’t think of it. Maybe they figure buyers will buy it themselves. I have no idea.

[tomm.brz]

Makes sense. I think i'm gonna buy it then
Any particular spec of it necessary?

[Irace86.2.0]

Originally Posted by tomm.brz

Makes sense. I think i'm gonna buy it then
Any particular spec of it necessary?

A good check valve would be just as good as a new PCV. I didn’t need this mod, but I did it anyway, yet I had a plastic one fail/break, so don’t go cheap. I went with the WRX PCV from the FA20DIT motor. It fit, but I don’t think the threads are the same length, so it doesn’t seat the same. I can’t remember if it is a tapered fit or something. It works regardless. A good quality check valve would be easier to install.

[bfrank1972]

Resurrecting this thread for a bit - have a vortech kit installed with a mishimoto pcv catch can, the vortech kit comes with a check valve to manage positive manifold pressure but it doesn't fit the larger hose between the manifold and catch can. Suggestions on a check valve that will fit? The boomba ones were suggested before but looks like they're no longer available. Searching around but not finding much surprisingly, needs to be sized 1/2" or 12mm I believe. I thought about splicing on the other hose with the one vortech included but I'd like the check valve between the intake manifold and the catch can. Thanks!

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[tomm.brz]

Or take a wrx pcv valve and do not use a check valve

[bfrank1972]

Originally Posted by tomm.brz

Or take a wrx pcv valve and do not use a check valve

Right but then the manifold will be pressurizing the hoses and catch can all the way down to the block. Doesn't sound ideal to me?

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[tomm.brz]

The wrx pcv will block anything coming from the manifold
Exactly like the check valve you want to put

The problem of the oem pcv is that it leaks from manifold to the block, with the wrx pcv you can skip the check valve

[Irace86.2.0]

The Harrop kit actually doesn't need the WRX PCV or check valve, but installed both anyways. The plastic, Amazon, check valve cracked/split in two after a short time, causing an air leak that wasn't noticed until my car couldn't idle well. The WRX PCV is still there.

[bfrank1972]

Originally Posted by tomm.brz

The wrx pcv will block anything coming from the manifold
Exactly like the check valve you want to put

The problem of the oem pcv is that it leaks from manifold to the block, with the wrx pcv you can skip the check valve

Ok it's bad picture time Attached picture showing the two scenarios I'm talking about - I can see that just using an STI PCV with a PCV catch can setup in front of it will reverse pressurize the PCV can which could then leak or cause issues with the catch can. I'm running probably 10ish PSI at redline so nothing crazy, so maybe I'm making too much of it. But it seems that a good billet check valve just at the manifold PCV inlet would be a better solution - shame that boomba doesn't sell them anymore, but somebody must! Having a hard time finding one the right size though. Anyway LMK your thoughts, maybe I'm overthinking it...

[dholloway543]

BE CAREFUL!!!!!

I purchased an FA20DIT from a wrx when I build my engine due to the fact that my ARP head bolts striped the block on the stock block.

The starter goes on the driver side for the FA20DIT and the oem frs trans only fits the starter motor on the passenger side.

DO NOT BUY THE FA20DIT FOR THE FRS UNLESS YOU HAVE A WRX TRANSMISSION!!!!!

FA20DIT https://surgeline.com/wp-content/upl...NG-1313-13.jpg


FA20 https://encrypted-tbn0.gstatic.com/i...JGmYGuEQoWJQ&s