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Engine Catch can

Y0UKN0WITSCHRIS

Well-Known Member
#1
So I was looking under the hood of my car today trying to find a spot to mount a catch can from my previous car and it dawned on me.. there’s lil to no room to mount it lol. And also the pcv lines on this car are kind of strange. Has anyone successfully mounted a catchcan to the VN yet ? And what setup you guys running? I’d like to get one on her as soon as possible !
 

Stash-N

Well-Known Member
#2
So I was looking under the hood of my car today trying to find a spot to mount a catch can from my previous car and it dawned on me.. there’s lil to no room to mount it lol. And also the pcv lines on this car are kind of strange. Has anyone successfully mounted a catchcan to the VN yet ? And what setup you guys running? I’d like to get one on her as soon as possible !
Search the posts of @TarmoT . Pictures included.
 

Cygnus X-1

Well-Known Member
#6
Oh boy... The Mishimoto compact catch can (and clones) is not a good catch can. I ran one for a little while on my VT.

The circular baffle plate is insufficient so you should add extra stainless (and/or copper) scrubber media, but it’s not easily added above the baffle. Even with extra media added, it did not filter well at all. It’s impossible to maintain the extra media without making a complete mess.

The bronze filter element at the outlet suffers from oil wicking through it.

A proper can should ideally have multiple chambers, each with filtering media, be simple enough to take apart and clean (without loose media falling out), filter well enough so that a screen/filter on the outlet is unnecessary and flow air well enough to not cause backpressure upstream (valve cover).

Contrary to what a lot of people think, the idea is to catch oil only, while still passing air and fuel vapors. Keep the cans warm with the shortest possible tubes. For this reason, the better air/oil separators on other platforms (e.g., Perrin) have coolant line connections and drain oil back to the pan or somewhere else in the oiling system.
 
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#7
Oh boy... The Mishimoto compact catch can (and clones) is not a good catch can. I ran one for a little while on my VT.

The circular baffle plate is insufficient so you should add extra stainless (and/or copper) scrubber media, but it’s not easily added above the baffle. Even with extra media added, it did not filter well at all. It’s impossible to maintain the extra media without making a complete mess.

The bronze filter element at the outlet suffers from oil wicking through it.

A proper can should ideally have multiple chambers, each with filtering media, be simple enough to take apart and clean (without loose media falling out), filter well enough so that a screen/filter on the outlet is unnecessary and flow air well enough to not cause backpressure upstream (valve cover).

Contrary to what a lot of people think, the idea is to catch oil only, while still passing air and fuel vapors. Keep the cans warm with the shortest possible tubes. For this reason, the better air/oil separators on other platforms (e.g., Perrin) have coolant line connections and drain oil back to the pan or somewhere else in the oiling system.
So you have a Perrin air/oil separator on your N? Or what are you using? Never had a GDI car so I never used an oil catch can before. Also didnt find that much info in this threat. Glad if you can help.
 

1FastStagea

Well-Known Member
#9
Just something I thought about and figured I'd share, for anyone interested in adding catch cans to your system make sure that if you're putting a catch can on the front PCV that runs to the intake manifold that you get a completely sealed (not the ones with the plastic tube level sights on the side) catch can that can handle boost pressure and vacuum or else you'll just be introducing a massive boost leak into your intercooler piping as well.

The one that goes to the intake on the backside of the engine (just in front of the turbo), you can use any variety of closed loop catch can (I highly suggest avoiding ones that are vented to atmosphere).
 

1FastStagea

Well-Known Member
#11
Any special reason why you suggest avoiding VTA?
Well 2 reasons actually, 1 is it's illegal in most places, but the second and most important is because VTA doesn't provide as much (or any, for that matter) vacuum on the PCV system and thus doesn't do as good a job of helping seal the rings which in turn helps generate a bit more hp/tq (a benefit of a properly working PCV/crankcase vacuum pump setup used in high performance applications) vs. recirculating back into the intake.

Or even better, having a dedicated vacuum pump setup to maximize crankcase vacuum and ideally evacuate it into a catch can (not back into the intake since oil lowers octane rating and increases the likelihood of preignition). That's going a little too in-depth for the average bloke looking to prevent oil buildup on the intake side of the engine though lol.

Plus I don't know about you, but I don't particularly enjoy the smell of oil vapors, nor having my engine bay get a nice oil spray as you drive. :p
 
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Cygnus X-1

Well-Known Member
#12
What we’ve seen on the VT1 platform is that at WOT, everything vents through the breather tube and not the PCV valve. Vacuum provided by the pre-compressor intake tube airflow is insufficient. Higher pressure through a single small orifice causes more oil to be produced, along with there being no baffle mechanism on the underside of the valve cover which would eliminate splashing oil from hitting the outlet.

Since the Gamma (G4FJ) engine has an abnormally high amount of blow-by (from poor rings, higher boost pressures & easy break-ins), some of us deemed it better to not feed the hot oily air back into the pre-compressor air stream. This coats everything all the way through the charge system to the intake manifold runners with octane-lowering oil, which raises IATs and increases risk of detonation.

We chose to not only vent both the PCV and breather sides, but added a third outlet using a vented oil cap. Overall performance increased and oil emissions actually substantially decreased.

A vacuum pump evacuation assist method was brought up, but the cost and complexity (not to mention weight gain) for minimal performance gain over just venting nipped it in the bud.

The PCV system is an archaic, outdated mechanism that is in sore need for a revised model, particularly for performance cars.

Getting to the Theta-II engine on our VNs, from what has been reported and from what I’ve seen personally, much less oil is coming through the breather tube due to better ring sealing. I’m keeping mine as is for now, but once boost pressures start going up, I’ll be checking the breather tube much more often.

At the first hint of accumulated oil, triple venting will be done. I’m not recommending it officially, but just know it is effective, does produce a slight performance benefit and produces far less hydrocarbon deposits on associated engine internals.

Evacuation tubes can be routed out of the engine bay and attached to the exhaust system for a quasi-vacuum assist, or just dumped under the car. If you don’t want to mess with your pollution control system for legality purposes, you can get around that by implementing the vented oil cap.

YMMV.
 
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1FastStagea

Well-Known Member
#13
What we’ve seen on the VT1 platform is that at WOT, everything vents through the breather tube and not the PCV valve. Vacuum provided by the pre-compressor intake tube airflow is insufficient. Higher pressure through a single small orifice causes more oil to be produced, along with there being no baffle mechanism on the underside of the valve cover which would eliminate splashing oil from hitting the outlet.

Since the Gamma (G4FJ) engine has an abnormally high amount of blow-by (from poor rings, higher boost pressures & easy break-ins), some of us deemed it better to not feed the hot oily air back into the pre-compressor air stream. This coats everything all the way through the charge system to the intake manifold runners with octane-lowering oil, which raises IATs and increases risk of detonation.

We chose to not only vent both the PCV and breather sides, but added a third outlet using a vented oil cap. Overall performance increased and oil emissions actually substantially decreased.

A vacuum pump evacuation assist method was brought up, but the cost and complexity (not to mention weight gain) for minimal performance gain over just venting nipped it in the bud.

The PCV system is an archaic, outdated mechanism that is in sore need for a revised model, particularly for performance cars.

Getting to the Theta-II engine on our VNs, from what has been reported and from what I’ve seen personally, much less oil is coming through the breather tube due to better ring sealing. I’m keeping mine as is for now, but once boost pressures start going up, I’ll be checking the breather tube much more often.

At the first hint of accumulated oil, triple venting will be done. I’m not recommending it officially, but just know it is effective, does produce a slight performance benefit and produces far less hydrocarbon deposits on associated engine internals.

Evacuation tubes can be routed out of the engine bay and attached to the exhaust system for a quasi-vacuum assist, or just dumped under the car. If you don’t want to mess with your pollution control system for legality purposes, you can get around that by implementing the vented oil cap.

YMMV.
Did the Gamma engines have the exact same dual-port PCV/vent system that our 2.0T Thetas have? Kinda strange that the intake pipe had insufficient flow for proper evacuation/scavenging for the PCV. Maybe due to the small tube diameter used on the OEM systems? I know my older Japanese engines have huge PCV piping in comparison and have no issues using the intake(s) to create ample vacuum for the PCV system.

Also just to clarify, you ran all 3 PCV/vents to atmosphere with your previous setup, or did you leave the 2 factory ones in place and add the vented oil cap?
 

Cygnus X-1

Well-Known Member
#16
SXTH’s first single and dual kits for the VT1 used Radium catch cans, which are quite good. Then they decided to roll their own cans.

I haven’t seen their filtering/baffling internals, so I can’t yet comment on its filtering efficiency or flow capacity.

Not exactly an inexpensive solution, but their build quality is normally top shelf.
 
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Y0UKN0WITSCHRIS

Well-Known Member
#17
SXTH’s first single and dual kits for the VT1 used Radium catch cans, which are quite good. Then they decided to roll their own cans.

I haven’t seen their filtering/baffling internals, so I can’t yet comment on its filtering efficiency or flow capacity.

Not exactly an inexpensive solution, but their build quality is normally top shelf.
https://www.sxthelement.com/Veloster-N-Dual-Catch-Can-Kit-p/14-03-700.htm link to the webpage they have a flow diagram and internal view. Looks like a nice setup and the price isn’t too bad for a dual catchcan setup with all applicable fittings and lines
 

Cygnus X-1

Well-Known Member
#18
Disappointingly, it looks lke a similar take on the Mishomoto compact can design. 40µ filter may be too much of a flow restriction. Can’t easily add/maintain extra stainless/copper media without making a mess.

Who wants to sit there and unscrew the bottom portion off of each can just to check the volume? Not I.

No petcock nor bottom connection for in-place/remote draining.

I’m sure the proximity to the downpipe will keep it warm enough, but maybe too warm.

Pass.
 
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#19
Disappointingly, it looks lke a similar take on the Mishomoto compact can design. 40µ filter may be too much of a flow restriction. Can’t easily add/maintain extra stainless/copper media without making a mess.

Who wants to sit there and unscrew the bottom portion off of each can just to check the volume? Not I.

No petcock nor bottom connection for in-place/remote draining.

I’m sure the proximity to the downpipe will keep it warm enough, but maybe too warm.

Pass.
Thanks
 

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