Check this catch can setup

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BHFR-GTR
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the crankcase vent to the exhaust is by far the best way, we run these on our 750 hp 400ci small block pulling truck, or header evac. it makes the most sense, and it was the only way to stop the motor from blowing oil out the valve covers and setting the headers on fire. a lot of the big hp pulling guys say they have seen a good 40-50 hp with a proper header evac setup on the dyno versus the popular venting to atmosphere


zil40
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Darius wrote:Since you have no idea about my setup, the status of my engine, or the specifics of where my catch can outlet is, I will refrain from responding to your newb comments about "engine failure" causing a situation that "isn't very safe" by "coating the road in front of (my) rear tires".
you already said it in your posts above. "newb"? you judge my knowledge off of my friends username, and how many posts he's made? wow, forum tuner. i'm not the one venting oil onto the road or track. to o.p. sorry for the distraction. i didn't want anyone to think that venting to road surface is a good idea.

Darius
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Forum tuner? That's flippant. And I don't base my opinion of your knowledge on your post count (or your friend's post count, whatever). I base it on your strong overreaction of paranoia to my vague comments on the quantity of oil coming from my PCV system.

It is frustrating that I cannot show what I'm talking about, but if you ever saw the area around a vented catch can in an engine bay, you'd know that everything near it is coated in oil. I'm not talking dripping, track-soaking quantities. It is a film like cooking spray. Hence, rust-proof.

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Shocker
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BHFR-GTR wrote:the crankcase vent to the exhaust is by far the best way, we run these on our 750 hp 400ci small block pulling truck, or header evac. it makes the most sense, and it was the only way to stop the motor from blowing oil out the valve covers and setting the headers on fire. a lot of the big hp pulling guys say they have seen a good 40-50 hp with a proper header evac setup on the dyno versus the popular venting to atmosphere
Mind going into detail about this? I've seen it setup on a supra in a recent vid I viewed. However it seems that it only vents when unloaded, at that point in vents a TON of white smoke out the exhaust...

Heres the vid and pictures of his setup. I take it those are one way valves on the exhaust? Is this what you run as well?

http://videos.streetfire.net/v...c7a5c






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Coolwhip
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correct, one way check valves just like your PCV.

For obvious reasons you don't want them in front of your O2 sensors but having them angled to where the stream of the exhaust gas pulls the vapor from your engine/crankcase.

Running a nicely setup catch can which knocks the oil out the vapor before the vapor is extracted through the exhuast helps as well.

BTW, the RB forum must have like 64 of these catch can discussions by now, haha.

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Neejay
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I have no doubt about the exhaust setup, but it's not practical for me right now.

Coolwhip: What do you think about venting to atmosphere with a tube running down under the chassis, and would you guys block or leave the oem pcv valve setup?

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nelson8708
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Just a few pics of some setups. Just T together the valve cover before going to the catch can. Plumbing into the exhaust is good but, not necessary for most street applications unless you have a real tired engine or have 400+whp.

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Neejay
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For this one, should I just T the valve cover fittings, then use another T to match up with the PCV valve hose that goes into the catch can? This one seems pretty good because boost won't pressurize the catch can, but it's still functioning properly. Right?

Darius
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Yep and like I said before, the drawbacks to this are that it is not for blow-thru MAF setups and you will still get oil into the intake, catch can or not. Take your pick and see how it works for you and go from there. We're only looking at $50 max to change between different setups.

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Cjmartz2k
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I'm pretty interested in this exhaust routing thing. I'm sitting around mid 500hp at the wheels AND I have a tired motor with a lot of blow by (actually I think I have a cracked head). I'm still struggling to see how the exhaust pulls gases out of the crankcase. Can you elaborate? I'm mostly just looking to remove the smell emanating from under my car (I vent right onto the road just like most here on Okinawa, I don't care, kiss my ***). How could it help hp wise also?

I might just re-route the hose into the same box/area as the intake. The "drippin's" could still fall down below the car, but the stank fumes could float up from one area into another into the intake. It's really only smelly at idle when the car isn't moving.

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nelson8708
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I read a really good thread (I found it....look down one post) on the different pcv setups and running the system to the exhaust worked good. He used a map sensor Tee'd into the line to see if he got a positive pressure reading and he did. It was a very small pressure but, when cruising around town it would switch from vac to positive pressure and back. It was a very small amount of positive pressure and not a big deal. However in WOT conditions the exhaust setup pulled the most vacuum (2"). Running the system to the intake post mafs and pre-turbo with a slash cut pipe always had a slight vacuum even when cruising but, at WOT it created 1" of vacuum. Not as much as the exhaust but, still a negative pressure. To quote a friend off a local forum "on honda-tech recently, tony1 setup a map sensor to his block while making a pass to see how much pressure there was in his block at 40psi (over 850whp easily), and with two large lines off the valve cover, and two large lines off the block, he saw 0psi in the block. "...Anything more than this setup is over kill.

I put these together a while back. They function and they are cheap (<10$ each).

^add a little spray paint and i'm good to go

p.s.My cell phone picked up some weird colors......my carpet is not multicolored as it appears


Modified by nelson8708 at 9:21 PM 1/6/2009

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nelson8708
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Quote »-----------------------------------------------------------------------------------------Intake Manifold Vacuum Assisted Ventilation----------------------------------------------------------------------------------------

In Turbocharged vehicles the Intake manifold sees both vacuum and boost pressure unlike in naturally aspirated cars. The PCV valve acts as a check valve blocking any pressure in the rare occasion their is backfire in the Intake Manifold. I have heard that some individuals placing a check valve in-line and allowing the Intake manifold to assist in ventilating the crankcase. The check valve insures that boost pressure doesn't enter into the crankcase through this line.

Ideally one would want to induce a gradual amount of vacuum up to 15 in/hg under full load. Connecting the evacuation line to the intake manifold would do the exact opposite of this. On a boosted vehicle the Intake Manifold will read 25in/hg at idle and 20-15in/Hg in low load conditions and quickly disappear when any moderate to high load conditions appear.

In a stock vehicle this is acceptable because the PCV valve meters the vacuum as shown:

Idle, Low load--- high vacuum pressures fully retract the pintle causing only a small vacuum draw on the crankcase.

Mild load conditions--- vacuum present in the intake manifold is not as strong so the pintle sits in the middle of the pcv valve allowing more vacuum to evacuate the crankcase.

High load + WOT conditions--- their is almost no vacuum present and the pintle is almost completely extended allowing the most amount of gasses to be drawn into the intake manifold.

Engine backfire--- the pintle fully extends and seals to eliminate any gasses from flowing from the intake manifold to the crankcase.

Not only are you pulling excessive vacuum at low load conditions you are contaminating the Intake charge with oil and unburnt fuel blow-by.

I cannot recommend this setup to anyone.

-----------------------------------------------------------------------------------------Intake slashcut evacuation-----------------------------------------------------------------------------------------

Using a slashcut tube to create vacuum is an old trick which works on the Bernoulli effect as air rushes past the tube at high velocities. Make sure you place the slash-cut opening in the opposite direction of the airflow.

One method for evacuating the crankcase is to allow the Intake(pre-turbo) to draw out these gasses. In my tests their was a linear load dependent vacuum drawn using this method. None to insignificant amount of vacuum drawn at idle and low load conditions, moderate load created 0.25 psi(0.5") of vacuum, and high load/WOT created a maximum vacuum of 0.5 psi (1") vacuum. One does not need to use a check valve with this approach as their is never any reason for pressure to force its way into the crankcase.

Their is a positive and negative aspect to this approach. The great thing about this method is that it is the only method which allows one to completely eliminate any blow-by gasses from contaminating the environment. The downside is that it contaminates the Intake charge with a used air charge.

Judging from the amount of contaminants I collected in my open breather catchcan every 2-3 weeks it would be absolutely insane to use this method without a sealed(no open breather element) and baffled catchcan in-line between the crankcase /valve cover and the intake. Keep in mind that most of the contaminants will be sucked into the intake as opposed to only some contaminants trapped in an open breather catchcan while the rest pollutes the environment.

Bottom Line

Cost: 20-150 dollars(dependent use of catchcan and welding)Performance: Good(as long as the compressor housing/Intercooler are cleanedperiodically and a catchcan is used)Reliability: Good.Environment: Excellent(provided that you use no other open breather elements)

-----------------------------------------------------------------------------------------Exhaust slashcut evacuation-----------------------------------------------------------------------------------------

This is based upon the same Bernoulli effect mentioned before but uses exhaust gasses to draw out crankcase gasses instead.

Their are 2 ways of doing this:

1) Weld a slashcut tube in your waste-gate dump-tube2) Weld a slashcut tube in your exhaust

In the first test I connected my Dewyer Magnehelic Pressure Gauge to the slashcut in my wastgate to measure the vacuum draw. As expected I only saw maximum vacuum drawn when the wastgate was open after reaching my maximum boost pressure set on my boost controller. The amount of vacuum went up from 0.25psi(0.5") to 0.4(0.8") vacuum. The numbers shown here were very similar to those shown with the Intake slashcut with the exception of being present when the wastgate started to open.

I chose to connect my valve cover breather and top port (oem- not modified plugs) on my block to the waste-gate slashcut tube. Check valves aren't really needed here but you can use one if it make you feel better.

For my second test I welding in a slashcut tube in my downpipe(12" from turbo). At first I had problems melting my high temp tubing with the heat from the downpipe and exhaust so I soldered together some copper pipe to solve this problem. I placed a check valve in-line on the top 6 inches of hose and wrapped it in reflective heat wrap as you can see.

At Idle the Dewyer Magnehelic Pressure Gauge showed 0.1-0.2psi of vacuum. Driving around town was more unpredictable. The gauge would oscillate between positive pressure(when i tested without the check valve) to 0.5 psi (1") to 1.1 psi ((2.2"). It rarely displayed positive pressure but I could find no simple pattern either rpm or load dependent. Typically it would bounce around 0.6psi to 1psi.

Here is a picture of the hose connected to the valve cover port without being tested. You definitely want to run a one way check valve in-line here.

I purchased the check valve for 1 dollar at a local junkyard. You can find the check valve in-line on the brake booster line on any honda.

Another source for a check valves and slashcut tubes(In case you don't feel like cutting your own is Moroso:

Bottom Line

Cost: 20-80 dollars (dependent upon if you have it welded or not)Performance: Great.Reliability: Great.Environment: Poor. [/quote]The only thing i dont agree on is that he says when using the intake method that you would have to clean the compressor and the intercooler because it would get dirty. I ran my valve cover straight to my turbo intake with no catch can for probably 8K miles and when i decided to change my setup my turbo compressor/fan was still clean. I guess i didnt have much blow by but, if you have a good catch can i dont think that would be a problem.
Cjmartz2k wrote:I'm pretty interested in this exhaust routing thing. I'm sitting around mid 500hp at the wheels AND I have a tired motor with a lot of blow by (actually I think I have a cracked head). I'm still struggling to see how the exhaust pulls gases out of the crankcase. Can you elaborate? I'm mostly just looking to remove the smell emanating from under my car (I vent right onto the road just like most here on Okinawa, I don't care, kiss my ***). How could it help hp wise also?

I might just re-route the hose into the same box/area as the intake. The "drippin's" could still fall down below the car, but the stank fumes could float up from one area into another into the intake. It's really only smelly at idle when the car isn't moving.
For high HP applications i would not use the intake method because you dont want the blow by gases to get back into your intake. It can lower the octane of your fuel and cause problems. For street cars its no big deal imho.

Darius
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Cjmartz2k - air rushing past an opening causes eddy currents at the opening that pull at the fluid (gas or liquid) in the port. This is a vacuum condition. The higher the velocity across the inlet, the greater the vacuum. A slash-cut or angled opening might be more efficient, but I have no idea. Nor do I claim to know how the power is affected by the crank case being under significant vacuum. In either case, this vacuum is being used to help "pull" crank case gases out.

I agree with the comment from tony1 on hondaforums or whereever that the crank case will not see pressure if the valve covers are vented to atmosphere. There simply is not enough restriction to create a significant positive pressure in the block. It is like trying to pressurize a baloon with a huge hole in it. The air just rushes out the hole.

On a side note, I took my PCV system apart tonight to swap out my crappy rubber hoses with SS braided line and fittings

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Neejay
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I think I'm just going to go with this:



I'll look into the exhaust method once I start making higher whp.

EDIT: nelson8708 thanks a lot for the good info.

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Coolwhip
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you and those T fittings, lol.

Hey Matt, tell me you finally man'd up and used the AN fittings to the cover, lol :P

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Neejay
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Coolwhip wrote:you and those T fittings, lol.

Hey Matt, tell me you finally man'd up and used the AN fittings to the cover, lol :P
lol It's either that or I run them down to the bottom of the chassis, open to atmospheric. lol

Darius
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HAHAHAHA I am all that is maaaaan!

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Coolwhip
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why not save yourself the T's and just run everything direct, it'll be a cleaner install

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nelson8708
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Neejay wrote:I think I'm just going to go with this:
Dont forget to slash cut the tube going into the intake. I was just going to weld mine to the out side @ a 45 degree angle until i learned the slash cut creates more vacuum. Here is a pic of the new intake i made for my ka-t with the slash cut tube.


Darius
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Slash cutting makes sense, but production cars do not have slash cut openings so either way will work. The vacuum is more affected by the velocity of the air passing by the opening. Run a smaller intake tube for more vacuum at the sacrifice of increased piping losses

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Neejay
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Darius wrote:Slash cutting makes sense, but production cars do not have slash cut openings so either way will work. The vacuum is more affected by the velocity of the air passing by the opening. Run a smaller intake tube for more vacuum at the sacrifice of increased piping losses
Yeah, it's a stock swap, and I don't have access to a welder. This configuration will have to do for now. (mine with Coolwhip's configuration)

Thanks though!

gawdzilla
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i would think the engine sucking in that air would be more than sufficient to create a good vacuum. have you ever put your hand over an open intake at idle? it's like a vacuum cleaner

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Coolwhip
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this is true.

block off the PCV valve and run it to the intake.

I did this on my first RB25. PCV block on both valve cover and intake manifold. Ran both lines to catch can, then to intake pipe. Worked

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Neejay
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Coolwhip wrote:this is true.

block off the PCV valve and run it to the intake.

I did this on my first RB25. PCV block on both valve cover and intake manifold. Ran both lines to catch can, then to intake pipe. Worked
I guess you have a point.

Is there any reason to keep the PCV valve if both valve covers will be vacuumed at all times anyway?

Darius
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No.

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krayton
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Coolwhip wrote:this is true.

block off the PCV valve and run it to the intake.

I did this on my first RB25. PCV block on both valve cover and intake manifold. Ran both lines to catch can, then to intake pipe. Worked
i was told to keep the pcv for just idling.

but i plan on ordering (ish forgot where) the exhaust vacuum ports. they weld into your exhaust with a AN fitting. then you can just run your catch can there. they also have the slash cut to create a vacuum from the pushing exhaust air

edit: im also running 2 catch cans. a greddy with lines right off the valve covers. then a DIY setup found on the internet for the pcv side. its a cool little water separator for compressors.

heres a link: http://www.s2ki.com/forums/ind...52&hl=

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Coolwhip
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krayton wrote:edit: im also running 2 catch cans. a greddy with lines right off the valve covers. then a DIY setup found on the internet for the pcv side. its a cool little water separator for compressors.

heres a link: http://www.s2ki.com/forums/ind...52&hl=
yes that water seperator mod is really nifty, actually installed on on a TT 350z.

However, due to the size, we've seen it fill up constantly, and no the engine did not have blown rings or such. Atleast we know it was catching alot of the oil from the vapor before it returned into the engine.

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Neejay
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I can't find a suitable plug for the PCV port, so I'm just going to route it stock for now. I've replaced the pcv valve with a brand new one.

I'll do the valve covers -> catch can + SS pot scrub -> intake for now.

Darius
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You can drill and tap the existing PCV valve hole with a 1/2" NPT plug. I know you have an RB20, but it may be the same diameter. If nothing else, leave the PCV valve on there and buy a rubber cap to cover the barbed end of the PCV valve.

OOPS, you have an RB25. My bad.
Modified by Darius at 10:40 AM 1/13/2009

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Neejay
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Darius wrote:You can drill and tap the existing PCV valve hole with a 1/2" NPT plug. I know you have an RB20, but it may be the same diameter. If nothing else, leave the PCV valve on there and buy a rubber cap to cover the barbed end of the PCV valve.
I have a RB25. Oh, great. I'll just cap it then. Thanks man.


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