# Crank case ventilation to exhaust



## GolfPuttPutt (Sep 27, 2013)

I have been doing some research on crank case ventilation scavenging by exhaust vacuum and I have found a few concrete details and a few convoluted details.

Concrete:
1: Slash cut pipe needs to enter exhaust pipe at 45 degrees

2: Slash must be parallel or close to parallel with the flow of exhaust (not perpendicular)

3: I hear the best outcomes have come from the Vibrant E-vac slash pipe:









4: check valve to prevent back flow of exhaust into crank case is necessary and people have had the best results placing the valve further up from where the slash cut pipe enters the exhaust.

Convoluted:

1: Some people have had issues with the moroso check valves:








and some have recommended the napa check valve:









2: Catch cans, should they be included? I hear some have used them and prevented some white smoke from exiting the exhaust. Has anyone used a catch can with this system and had ill effects? IE: a reduction of vacuum because of the baffles. If someone has used it, how much fluid have you drained in what amount of lapsed time?

3: WHERE???? This is the most convoluted of aspects of this system. Some say it is best right after the turbo to harness as much flow as possible (those who say this usually run cat-less) Some say right after the cats, as restriction and turbulence is the LEAST directly after the cats and some say they run it way down at the tip of the exhaust (some subaru dudes) This, is apparently the most important aspect of gathering as much vacuum possible so I really would like to get a consensus on what people are doing on their street cars to build the most crank case ventilation vacuum.

I'm working with a 1.8T 260WHP so far  and am not really interested in VTA catch cans or the stock PCV system or any slight variations of PCV (or routing crankcase fumes back into the intake)

So who's done this? Who can help a fella out?


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## GolfPuttPutt (Sep 27, 2013)

Just read a post recently, if anyone is paying attention to this thread:




> "When measuring how much vacuum the exhaust was pulling, in the lines it was running around 2-5” on each bank which is ideal, but at higher rpm, that reduced as the amount of blow by/boost/pressure increased. Also when measuring at the crankcase, I cut up an old oil filler cap and installed a adapter and vacuum gauge in the car so I could measure the actual crankcase vacuum rather than what it was showing in the lines, it was showing less vacuum than in the lines as obviously in the crankcase its pulling more air/space than in the actual lines going to the exhaust.
> 
> I found out the main reason why the exhaust wasn’t pulling as much as I hoped, was down to the fact the ventri tubes were mounted after the cats, which disrupted the flow, and the air velocity isn’t as high here. Also it may have been down to some back pressure. Ideally with the exhaust method, as you get on the gas, and more exhaust gasses are flowing the evac setup should pull more air, which is the case, but the amount of blow by/boost significantly increases and overweighs what the evac setup is pulling.
> 
> ...




So, I guess the question now is, will using the scavenging slash cut pipe prior to your O2 sensors mess with your Air fuel mixture ratio? My guess is yes, so it seems that only place to put this is after the cats. Can someone confirm this or is it possible to put the slash cut after the first 02 sensor or something?

Lost


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## warranty225cpe (Dec 3, 2008)

GolfPuttPutt said:


> Just read a post recently, if anyone is paying attention to this thread:
> 
> 
> 
> ...


You want it after the cats.


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## GolfPuttPutt (Sep 27, 2013)

have you tested what kind of vacuum you'd be pulling post cats on a stock 1.8t exhaust with the mid muffler still intact? I will prob have to test this myself, i'm just trying to see if someone else has done it before me.

Also, I have heard of people drawing 12-14" pre cats (unfortunately not an option, but it it drops to 1" at idle with positive pressure under boost, post cat, this mod is not worth doing on a stock exhaust 1.8t)


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## warranty225cpe (Dec 3, 2008)

I had a bung welded in my exhaust for this. I screwed in the valve, then got on the gas. I couldnt produce enough vac downstream of the secondary o2 to open the valve.


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## GolfPuttPutt (Sep 27, 2013)

did you scrap the idea? what are you using now?


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## zeusenergy (Feb 25, 2008)

1) Use original down pipe from valve cover location to PCV tee fitting under manifold and attach to valve cover with short 90 degree bent hose.
2) Take third port that used to go to PCV valve on manifold (3/4-1" diameter I forget) and attach hose repair barb to it with clamp.
3) Run large diameter 1" or so hose from tee fitting under manifold to the ground.

Draft tube FTW.


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## GolfPuttPutt (Sep 27, 2013)

draft tube will have an odor, draft tube will invite atmospheric moisture into engine easier, draft tube vents crankcase via blowby which has no performance benefits and promotes ring unsealing, it can also contribute to premature seal failure


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## warranty225cpe (Dec 3, 2008)

GolfPuttPutt said:


> did you scrap the idea? what are you using now?


Yeah, Im just using the stealth can from 42 routed back to the TIP.


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## zeusenergy (Feb 25, 2008)

GolfPuttPutt said:


> draft tube will have an odor, draft tube will invite atmospheric moisture into engine easier, draft tube vents crankcase via blowby which has no performance benefits and promotes ring unsealing, it can also contribute to premature seal failure


Used to have a filter on the PCV, and it was stinky under the hood- it was obvious. With the tube, no adverse smell any more. maybe if the car is running and you really sniff around you might catch it.
As for moisture- have you ever looked at what your catch can accumulates? Not just oil- water vapor condenses in it too- purely from blow-by gasses which are atmospheric in origin to begin with. Think about the volume of air going into the engine from the air filter- Is the ambient humidity going to be removed from the air when it gets ingested? Even when the motor is not running, ambient air humidity can still reach the PCV lines. Slightly buffered.
Lastly, have you ever cut the PCV "hockey puck" in half to see what kind of diameter of flow it can pass? It barely cracks open at all under full load, and passes a very small volume of flow. What I have done actually reduces the pressure inside the case over the stock configuration. Yes, a positive draw on the crankcase would be better than what I have! But using the TIP connection as a source of vacuum for purging case gases does NOT work unless you are in boost. You would need both that and the normal PCV valve to make the system work to any significant degree, and that means all the work you did to clean up the bay and remove or delete all the vacuum lines and hoses was for nothing. the best thing is a vacuum pump with a catch can vented to atmosphere. Second best is the draft tube, last would be stock. I would not use a catch can without an active pump.


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## GolfPuttPutt (Sep 27, 2013)

bumpity bump bump!

I have begun my quest to see if this **** will actually work. 
I bought a moroso check valve for testing but will be going with a napa check valve, very similar but more reliable. 

I have welded in the bung for the slash cut pipe directly after the catalytic converter. I will take pics soon and upload them of this location

This is on a 1.8T engine mk4

I am using stainless braided AN line with -10 AN fittings for the line from the slash cut pipe to the catch can. 

The hose and fittings and check valve are all assembled and ready to go: I will post a pic of this soon also

I am using -12 AN fittings for the line from the crankcase to valve cover to catch can. this is assembled and ready. I will post a pic of this soon also.

I still need to mess with my catch can and fabricate the baffle and paint it.




I hooked up the hose (and the check valve) and the slash cut pipe to the bung in the exhaust and attached a vacuum gauge to it and turned the car on........

ta-da! 5" of mercury! 

shut it off.

turned it on again.....ta-da another 5"

unscrewed the check valve to see what happens

tested: swinging needle between 1-5" of mercury and 1-3 PSI. Naturally, without the check valve, it's receiving the exhaust pulses and not the low pressure after pulses. Hence why the check valve is there. NICE! check valve works!

re screwed the check valve, tested again

damn....0-1" of mercury. Da-fuq happened?

now time to figure out what went wrong.


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## GolfPuttPutt (Sep 27, 2013)

also, in this picture: 









I have oriented the slash pipe the opposite way, the hole facing away from the exhaust stream.


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## GolfPuttPutt (Sep 27, 2013)

> Used to have a filter on the PCV, and it was stinky under the hood- it was obvious. With the tube, no adverse smell any more. maybe if the car is running and you really sniff around you might catch it.
> As for moisture- have you ever looked at what your catch can accumulates? Not just oil- water vapor condenses in it too- purely from blow-by gasses which are atmospheric in origin to begin with. Think about the volume of air going into the engine from the air filter- Is the ambient humidity going to be removed from the air when it gets ingested? Even when the motor is not running, ambient air humidity can still reach the PCV lines. Slightly buffered.
> Lastly, have you ever cut the PCV "hockey puck" in half to see what kind of diameter of flow it can pass? It barely cracks open at all under full load, and passes a very small volume of flow. What I have done actually reduces the pressure inside the case over the stock configuration. Yes, a positive draw on the crankcase would be better than what I have! But using the TIP connection as a source of vacuum for purging case gases does NOT work unless you are in boost. You would need both that and the normal PCV valve to make the system work to any significant degree, and that means all the work you did to clean up the bay and remove or delete all the vacuum lines and hoses was for nothing. the best thing is a vacuum pump with a catch can vented to atmosphere. Second best is the draft tube, last would be stock. I would not use a catch can without an active pump.


I agree with you on some things. Stock is probably the worst option. Vacuum pump is the best option. Tunable and effective. Also complex and has a lot of moving parts. But yes, the best. I think, maybe (what I'm trying to test) the slash cut exhaust pipe method could also pull a decent amount of vacuum. At least, more than stock and less than vacuum pump. It's also inexpensive, clean and if a successful system is established, can be reproduced for people wanting the same results. We shall see. 

I just don't think draft tube is the best for today's technology standards. But if this attempt fails, then yes, you are probably right on the order. Vacuum pump, draft tube, stock. If this succeeds, I would say Vacuum pump, exhaust scavenge, draft tube, stock.


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## GolfPuttPutt (Sep 27, 2013)

for anyone paying attention to this.

Purchased a Napa check valve today. Don't go with Moroso, go with Napa. The force that it takes to open each check mechanism is drastically different. Napa opens much easier.


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## AmIdYfReAk (Nov 8, 2006)

Just a question, why would you install it all the way behind the cat? Surely it would pull vac in front, and the cat would burn the stuff off as per most OE installs.


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## GolfPuttPutt (Sep 27, 2013)

yes, that is correct. I am not too concerned about my cats and the most 'optimal place' for least restriction would be prior to the turbo, right where it collects into the housing. Unfortunately, I need my O2 sensors which will have faulty readings due to air introduced into the exhaust system that isn't coming out of the cylinders.

putting the pipe directly after the cats, I can utilize it as a venturi-esque necking down segment of the exhaust. If I welded a trumpet onto the end of my cat, it would further increase exhaust flow out of the cat and increase vacuum in theory. This would require me to upgrade to a 2.5 or 3" catback exhaust. I'll be doing that soon. First I'd like to see if this works.


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## GolfPuttPutt (Sep 27, 2013)




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## GolfPuttPutt (Sep 27, 2013)

Apologies for the dirty bay. Trying to clean that bad boy up.










Engine bay, how the catch can will b e set up. The line from the top of the cc will go to the slash cut pipe. 

Going to run a few tests to see if the system works better with the valve closer to the exhaust pipe or further away or if it doesn't matter.










where the slash cut pipe enters the exhaust. Right after the cat on the stainless OEM downpipe.










The slash cut pipe and the moroso check valve. The napa valve def opens easier. I've been messing around with it. cut it open to replace the diaphragm with a silicon one instead the standard rubber one. Gotta seal up the valve again. These valves are very simple inside. It's basically a rubber disk attached to a metal plate with holes in it. The rubber disc seals on a raised surface on the plate. I can see the potential for it to clog very easily if one was to run a system like this without a catch can.


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## Yareka (Mar 5, 2002)

Nice progress. 
Were you able to figure out why you were able to pull 5" of vacuum and then only 1"? 
Was it the check valve and were you able to replicate the 5"?


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## GolfPuttPutt (Sep 27, 2013)

not yet, I'm in the process of sourcing another check valve in order to replicate it. 

At first, I thought, maybe by some small chance, the computer makes the wastegate opens on a cold startup and the bypass of the exhaust turbine is what allowed me to get 5" but I checked and the wastegate does not move at all upon startup. So I'm going to reassemble my line with a new sealed valve (where the two halves are crimped together) and slash cut pipe and give it another go.


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## Yareka (Mar 5, 2002)

You must have gotten 5" when the SAI was on during a cold crank? During that first 20 seconds there is a lot more airflow through the exhaust to heat up the cat. If so thats great since you'll want more vacuum at higher revs anyways, not so much needed at idle.


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## GolfPuttPutt (Sep 27, 2013)

SAI delete


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## GolfPuttPutt (Sep 27, 2013)

Found out vibrant also makes a billet check valve which looks nice and also looks sturdy. 










I'm probobly going to be going with this guy if I actually get it working. I'll see if I can integrate it into the catch can setup. I also like the AN fittings.


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## GolfPuttPutt (Sep 27, 2013)

first test with renditions:

teflon tape at connector between NPT-AN adapter to check valve to ensure seal.

teflon tape on vibrant e-vac slash cut pipe to AN 45 degree fitting for same reason

ensure all fittings are tight.










no luck.

second renditions:

turn slash cut pipe opposite way it was facing in the bung (exact positioning of e-vac image)

turn slash cut 90 degrees (facing sideways, try both ways....orient e-vac slash cut pipe all possible ways.)

retighten fittings.

seal rim of check valve with epoxy to prevent leakage:










results:










no go again.

On the end that attaches to the gauge from the check valve I am using a 5/8" rubber heater hose with jubilee clips. When this hose is pinched and released (upon release, not pinching) the vacuum jumps up to about 4-5" of mercury then settles back to .5". Not sure why this occurs. There may be a leak somewhere else I'm not realizing. OR, perhaps AN fittings are not rated for vacuum and will be able to achieve vacuum but not HOLD vacuum. This is a possibility, I'm in the process of contacting Earl's fittings about this matter.

If anyone has any info on AN fittings, I would very much appreciate the help as I do not have much experience with them. I know most are pressure rated for 1500 PSI but that's positive pressure and vacuum can be a little different. 

Next step is going to be removing the line and hooking the e-vac slash cut pipe up directly to the gauge and the check valve without AN line and fittings. Just heater hose rubber and jubilee clamps to see if this is possible with a simpler system.

I'm going to give Vibrant a ring soon to see what they recommend on placement for the bung on turbocharged applications. They say they guarantee 3" on race motors which is a pretty powerful pull after all the blow by pressure.


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## GolfPuttPutt (Sep 27, 2013)

This **** has got to be possible somehow, both me and my father saw the gauge read 5" when I first started this adventure (on two startups!)!!

http://cdn.*************.net/instances/250x250/37897351.jpg


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## spartiati (May 19, 2008)

Does the vacuum reading change at all with increased rpms?


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## Yareka (Mar 5, 2002)

spartiati said:


> Does the vacuum reading change at all with increased rpms?


And more importantly driving around at different loads/rpms and boost. I understand you are chasing that 5 that you briefly saw but seeing any vacuum at idle is good, increasing with load would be perfect.

And again, great job on working with this. I tried the moroso fitting/check valve a few years ago and never had any luck, at 5k rpms it would create positive pressure no matter which way I tried to angle it. I'm currently working on putting my SAI pump back in motion to draw crankcase pressure and then exit back into the exhaust like you have. I already have the boost activated harness ready to go, just need a better place to mount the catch can/SAI pump together. And I plan on doing the same vacuum measurements you have done and also a few dyno runs to see if it really does create power.


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## GolfPuttPutt (Sep 27, 2013)

Yareka: I thought about this, using the SAI pump connected to a catch can. It might work! careful it doesn't catch fire though for whatever reason. Also, you may need some tricky wiring to increase pump rpms as engine rpms increase in order to pull a harder vacuum.

If you can get an electric pump to work reliably, that is no doubt the best decision if you don't mind the smell or find a place to put it where it doesn't smell or freeze.



Believe it or not, the vacuum jumps very very slightly when I shift or close throttle suddenly. It tended to jump no higher than 2". I couldn't for the life of me get it to increase as rpms increased or as boost increased as the theory should suggest it would.


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## spartiati (May 19, 2008)

I was planning on doing this over the winter break so I just want to say thank you for posting about this.

Do you think its possible that the cat is interfering with flow enough to inhibit the amount of vacuum you are able to make regardless of rpms? Also I know the big block guys run these as close as possible to the headers (some even in the headers). 

I'm going to get around to doing this on my 3" catless exhaust hopefully by January.


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## All_Euro (Jul 20, 2008)

Awesome thread - keep up the good work :beer:


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## AmIdYfReAk (Nov 8, 2006)

spartiati said:


> I was planning on doing this over the winter break so I just want to say thank you for posting about this.
> 
> Do you think its possible that the cat is interfering with flow enough to inhibit the amount of vacuum you are able to make regardless of rpms? Also I know the big block guys run these as close as possible to the headers (some even in the headers).
> 
> I'm going to get around to doing this on my 3" catless exhaust hopefully by January.


Not even that, Alot of the Late 80's up to 2000's V8 have the Venturi built within the stock header and pull air into the exhaust as a secondary air rather than PCV. 

For example, check out GM's LT1.


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## GolfPuttPutt (Sep 27, 2013)

> Do you think its possible that the cat is interfering with flow enough to inhibit the amount of vacuum you are able to make regardless of rpms? Also I know the big block guys run these as close as possible to the headers (some even in the headers).


Yea that's a possibility and a big one. I bought another bung and i'm gonna weld it in right after the turbo to see if vacuum gets better and if it messes up my O2 sensors.


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## GolfPuttPutt (Sep 27, 2013)

but that also wouldn't explain why i achieved 5" of mercury post cats....

I also have -6 AN hose and fittings coming to me so I can test a skinnier line and see if line volume has an effect on vacuum.

Lots of tests to perform.


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## AmIdYfReAk (Nov 8, 2006)

install it AFTER the Primary 0/2, it wont mess with your fuel trims that way and the only thing that i can think off off hand is you may pop a code for the rear 0/2 not being happy.


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## spartiati (May 19, 2008)

Agreed. Go after primary o2.

Also a smaller diameter hose should increase velocity and likely increase vacuum as well.


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## spartiati (May 19, 2008)

What's the part number for the Napa check valve? No Napa close to me.


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## Brake Weight (Jul 27, 2006)

Liking these theories.

Make a 1-2" section of exhaust pipe that is a 1/2" smaller ID than the rest of the exhaust system or possibly neck down 1/2" then open up. Maybe 2.5" to 2" up to 3". Come in on a 45 or 90 degree angle with your tube, but have it bent and pointed in the direction of flow and just long enough to clear the small section of pipe. 

These are on every oil rig on the planet. They work like how I stated above but with liquid. But, the less viscous the liquid the better the vacuum. Usually something like a 6-8" line with a 2-3" bean back to 6-8". This creates a fair amount of back pressure so I'd guess that less deviation would be minimum. 









Flow in this picture is left to right.


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## GolfPuttPutt (Sep 27, 2013)

I know exactly the design youre speaking of. It could very much work very well. I would prob have to upgrade my catback to 3" (oem is 2 and 1/8th). Ive heard these kind of harsh necking down piping designs can change the resonance of exhausts, making them quieter which im ok with. Yea its prob going to create some backpressure but the design youre speaking of would be most ideal.

Ill draw up an image of what i think youre speaking of on tues when i get home.


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## GolfPuttPutt (Sep 27, 2013)

> What's the part number for the Napa check valve? No Napa close to me.


Napa part # 2-29000










Like this design but without the flapper valve right?


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## Brake Weight (Jul 27, 2006)

GolfPuttPutt said:


> Like this design but without the flapper valve right?



That'll do it! But back pressure would be an issue now. Figure one problem out and it leads to another. If you can figure the flow area between the restriction and the vent tube to determine pipe size needed to minimize back pressure.


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## GolfPuttPutt (Sep 27, 2013)

Found a file from some sort of diagnostic someone ran through a computer while testing their crankcase evacuation system.

not sure if its naturally aspirated or turbo charged...










10" Hg of vacuum


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## spartiati (May 19, 2008)

There are afew things that motor has to help it achieve more vacuum:
1) no turbo to disrupt exhaust flow if it is NA.
2) even though it's only one bank I'm sure it has an increased displacement over our 1.8t
3) 1.75" primaries will greatly increase exhaust gas velocity over the slashcut.
4) it says in the chart it is measured at 2700 rpms

When you move the slashcut pre cat I'm sure that'll help increase the vacuum in the system. Also I'd be curious to see if you can measure vacuum by revving it and at the same time driving it. I would assume Load would have some influence on vacuum.


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## GolfPuttPutt (Sep 27, 2013)

nvm I think that's a helicopter engine....


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## Brake Weight (Jul 27, 2006)

All the helicopters I've ridden in we're turbines.


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## Yareka (Mar 5, 2002)

Instead of starting a whole new thread ill leave this here for those in search of crankcase vacuum

http://forums.vwvortex.com/showthread.php?6875603-Electric-Crankcase-Evacuation


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## kg6dxn (May 4, 2012)

I've been running a system like this with good results. I used the Moroso check valve. I did have to swap one out after a few mile when it stopped sealing. I used a 0.75" PCV adapter from 034. It is plumbed via hard line to a home made catch can. From the can back to the check valve. My check valve is 12" from the turbo, just behind the O2 sensor. I staggered the O2 and check valve to work with the spiraling exhaust from the turbo.

I have not put a vacuum gauge on it but the catch can fills up with plenty of ****ty oil water. I had a butterfly valve on the bottom of the catch can but found it leaking so no it's just a plug.

3000 miles so far and working good.

PS. I have a 4" exhaust, no CATs, no EGR, no SAI, no rear O2, No smog... 325whp...


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## Brake Weight (Jul 27, 2006)

Bump.


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## radlynx (Jan 4, 2007)

i dont think its a good idea to vent the crankcase to the exhaust either before the cat or after. you need to remove the muffler or anything that is blocking the exhaust flow.

Sent from my SM-G930T using Tapatalk


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## Brake Weight (Jul 27, 2006)

Even with a 2.5-3” blow through muffler?


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## radlynx (Jan 4, 2007)

yes since the muffler is somehow blocked with holes. if you remove the muffler and just use a straight pipe, that might be possible. 



Brake Weight said:


> Even with a 2.5-3” blow through muffler?


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## Brake Weight (Jul 27, 2006)

radlynx said:


> yes since the muffler is somehow blocked with holes. if you remove the muffler and just use a straight pipe, that might be possible.


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## radlynx (Jan 4, 2007)

I think you will need a smaller exhaust pipe to have more exhaust flow. that might work.


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## Pisko (Jan 14, 2006)

just an idea, could one use the rear 02 bung, post cat, for scavange point? this would make it real esay to plumb up the pcv hose for most people.
On my A4 with cat+rear 02 delete, the bung is just down from the top of the valve cover, and runnning a line from the block up with a T would make this real easy to plumb up (and get rid of the pesky smell from my pvc dumping to the ground)


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## All_Euro (Jul 20, 2008)

Pisko said:


> just an idea, could one use the rear 02 bung, post cat, for scavange point? this would make it real esay to plumb up the pcv hose for most people.
> On my A4 with cat+rear 02 delete, the bung is just down from the top of the valve cover, and runnning a line from the block up with a T would make this real easy to plumb up (and get rid of the pesky smell from my pvc dumping to the ground)



Don’t have any results to post but this is exactly what I plan on doing with my A4...


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