pcv removal idea...

[dnhieu]

you should take some pictures of that....

 

[kanderson111]

His system will work, but why suck all that crap into the turbo and push it through the ic pipes and intercooler. The line on the intake is not necessary, the vented catch can vents during idle and during boost. In the winter you can see the steam come out the top of the vented catch can during idle.

 

[No_Skillz]

also this guys post ^^^^ is completly right about the air naturally comming out. i put my finger over the top (where the filter would go on the catch can) and it had a bunch of pressure behind it. this was when i boost leak tested it and while the car was at idle....

This happens because your rings aren't sealing.

EDIT: My bad on the guy I quoted. I just disagreed with you and then agreed with you half way down. I thought you meant it wouldn't suck anything out.

Don't worry, we're saying the same thing. I guess I should have said circulation during idle/off boost instead of ventilation to be more clear.

Furthermore on the setup: If you choose to ignore the fact that you will have less circulation in your crankcase at idle/off boost (not that big of a deal I guess) and go with this setup, you need to find some way to get rid of the nasty stuff coming from your crankcase.

You can use a filter on top of your catchcan, but you will need an aftermarket MAF since your intake will be pulling in unmetered air. You will also eventually get a nice oily, dusty, greasy, nasty coating throughout your engine bay.

Another option is to stuff the catchcan, or this stuff is going to coat your intake and IC. However, I don't know with what since I don't have any experience with this. Maybe someone else can offer a suggest.

The third option I can think of is to not have it connected to the intake. You don't need an aftermarket MAF with this, however you will need a breather filter... which will, like I said, coat your engine bay with crap.

It's really not that bad of an idea to keep the PCV and use the stock setup, just with a catchcan between the VC breather and the intake. Even if a faulty PCV lets a little air pass during boost, your VC breather is there to save the day.

 

[99gst_racer]

First off, I'd like to say "Great thread, guys". There is alot of good information and some good points being made here.

Tell me what you guys think of a set-up like this:

The gold squares designate straight fittings (No PCV valve).
The petcock valve is for easy draining.

 

[project_tsi]

Hey all, here's how I have mine setup. I drilled out the pcv hole with a 11/32" bit and tapped it with and 1/8" NPT tap. I also did this again by the ex. cam. I then used 2 1/8" NPT to -6an adapters and screwed on a 90* -6an pushlock fitting in the PCV spot, and I used a straight fitting by the cam. There is another stock breather in the middle of the VC that I just hooked a hose too b/c its already hollow. The trick is to drill your extra holes above the VC baffling so no extra oil is lost. I'll be honest, I'm not even running a catch can right now, I just have hoses dumping close to the ground, but the amount of oil it drops out is very minimal. I check oil levels multiple times daily, and I've never once had to put oil in. I will eventually run a catch can but I'm to cheap to buy one right now.

 

[No_Skillz]

Hey all, here's how I have mine setup. I drilled out the pcv hole with a 11/32" bit and tapped it with and 1/8" NPT tap. I also did this again by the ex. cam. I then used 2 1/8" NPT to -6an adapters and screwed on a 90* -6an pushlock fitting in the PCV spot, and I used a straight fitting by the cam. There is another stock breather in the middle of the VC that I just hooked a hose too b/c its already hollow. The trick is to drill your extra holes above the VC baffling so no extra oil is lost. I'll be honest, I'm not even running a catch can right now, I just have hoses dumping close to the ground, but the amount of oil it drops out is very minimal. I check oil levels multiple times daily, and I've never once had to put oil in. I will eventually run a catch can but I'm to cheap to buy one right now.

That's interesting... where do all the lines go? Just dumped to the ground? If so do you plan to run a catchcan soon and what type? What was the point of the extra fitting by the exhaust cams?

 

[project_tsi]

That's interesting... where do all the lines go? Just dumped to the ground? If so do you plan to run a catchcan soon and what type? What was the point of the extra fitting by the exhaust cams?

Yes, for now they dump to the ground, they dump about 2 inches below the crossmember. There is absolutley nothing dirty in the engine bay, no oil coatings, etc. I'm not sure what type of catch can I will run. If I buy one, I'll have to add another fitting b/c most only come with 2 inlets. I may end up making one out of PVC piping. and paint it black and hide it. Cheap and easy. The extra fitting is just for extra ventalation.

 

[jepherz]

Well, I kinda skimmed through the whole thread, but no, that setup will not 'draw' the gases out as it is meant to stock. Blow by will hopefully be caught in the catch can.

Why not do this? If you are expecting your catcan to work and catch all the oil blowby, why not just stick the catchcan inline with the line coming out of the crankcase vent? That way, the system will operate as normal, drawing the gases out at idle, but your oily residue problems will be solved?

 

[MILITISINVICTUS]

For anyone looking for a bottom line to this issue, here's the cheap, easy, effective solution:

Gut the PCV valve by drilling it out. Re-install. Plug the hole in the intake manifold that the PCV had fed into. Connect the end of the PCV valve to hose, put a properly fitting fuel filter (clear plastic) in line on that hose, and continue the hose to the intake. Take your valve cover breather line, stick another clear fuel filter inline on that, and feed it into the intake as well. Use a T-connection to combine your breather hoses if you don't have two pre-turbo intake ports available. I did.

Outcome:
Now you have nice negative pressure from your turbo making it easier for positive pressure to escape the crankcase. The filters keep the IC pipes clean. Maybe you even get a bit of that reduced resistance for the underside of the pistons that some folks try to achieve.

Afterword:
Unmetered air is not an issue here. The light (but better than stock) vacuum achieved by your two hoses is sufficient to serve the crankcase depressurization purpose but quite insufficient to cause a problem with seals anywhere (path of least resistance is that nice K&N a foot away).


Pictures and Fuel Filter Part Number suggestions available upon request.

 

[2blue4uRS]

Is there a way to pull the crankcase pressure without rerouting it back through the intake. My setup right now doesn't have a nipple on the intake pipe so I can't feed the line. I've looked at the dejon ones and I unsure if the crank vents actually work. Has anyone used these with positive feedback?

 

[sbiggi]

Is there a way to pull the crankcase pressure without rerouting it back through the intake.

Yes, get a steel brake line, slash cut it,.
Weld the slash cut into the exhaust after the cat with the cut facing back.
put a oneway valve similar to the pcv valve inline.

Under full load it will some pretty good vacumm.

 

[99gst_racer]

Gut the PCV valve by drilling it out. Re-install.

Or you could just buy a cheap $2.00 1/8 NT fitting, instead of taking the time to modify the PCV valve.

Outcome:
Now you have nice negative pressure from your turbo making it easier for positive pressure to escape the crankcase. The filters keep the IC pipes clean. Maybe you even get a bit of that reduced resistance for the underside of the pistons that some folks try to achieve.

The big question for me is:

How important is it to have negative pressure pulling on the crankcase pressure?

Obviously it will help, but can the crankcase release pressure adequately without a negative pressure source?

Yes, get a steel brake line, slash cut it,.
Weld the slash cut into the exhaust after the cat with the cut facing back.
put a oneway valve similar to the pcv valve inline.

Under full load it will some pretty good vacumm.

Yup. Old V8ers, hotrodders and drag racers have been using this type of Evac. system for a long time.

 

[99gst_racer]

I don't think there's going to be a big problem. You'll just have a nasty coating in your engine bay after a while with that setup.

It's not as bad as you may think. I've been running it like that for about 14 months, and the coating only extends to a 12" radius from the breather top.

I'm more concerned with having or not having a negative pressure source. What are the affects of having one as apposed to not having one?

 

[MILITISINVICTUS]

Or you could just buy a cheap $2.00 1/8 NT fitting, instead of taking the time to modify the PCV valve.

Well, we could get technical and add in the costs of mileage to the store, plus your time consumed in the process, plus the pain and suffering of being away from your tools, and come up with more than two bucks. I charge double OT for wandering through aisles, and standing in lines near whining kids..

Anyway, you're talking to someone with a boost gauge mounted in a pringles can, so the "did it because I could" factor is operant here.


The big question for me is:

How important is it to have negative pressure pulling on the crankcase pressure?

I don't know. I figure it falls between the latest news on Britney, and world peace. Roughly.

Obviously it will help, but can the crankcase release pressure adequately without a negative pressure source?

That depends upon the definition of "adequately".. if you have some slight ring blow-by, maybe it's a nice-to-have. Will never be a must-have, but as you say, it will obviously help a bit.

 

[dnhieu]

I dont understand how myset up isnt efficent like stock. i could be drawing a little less air under vacumme granted the intake isnt going to draw -15-18 vacumme but i got more ports for air to come out to make up for that. plus all air is accounted for so when i go get dsm link i wont be missing any amout of air if i dont have any boost/vacumme leaks.

someone mentioned it is point less to connnect to the intake, but he also agreed with me by saying that the port on the side of the intake will draw vacumme. well with the vacumme line connected to the intake im drawing vacumme like the pcv valve would be doing under vacumme. under boost conditions ill be letting out all the air in the valve cover. to me it seems fully functional plus i wont have oil in my intercooler piping and eliminated another boost leak spot.

 

[exile]

I was at a car show in Carlisle, PA last weekend and I checked out all of the 2g's throughly there to see if they knew what they were doing.

I seen a gentleman with a setup like you're all talking about, incorporated into the Greddy catch can he had for his valve cover breather hose.

 

[RayH]

Without any vacuum being applied and an available source of clean air, I'd be more concerned about the blowby contaminating the oil then the intake:

What is the PCV valve and what does it do?

 

[MyBeatGSX]

I dont understand how myset up isnt efficent like stock. i could be drawing a little less air under vacumme granted the intake isnt going to draw -15-18 vacumme but i got more ports for air to come out to make up for that. plus all air is accounted for so when i go get dsm link i wont be missing any amout of air if i dont have any boost/vacumme leaks.

someone mentioned it is point less to connnect to the intake, but he also agreed with me by saying that the port on the side of the intake will draw vacumme. well with the vacumme line connected to the intake im drawing vacumme like the pcv valve would be doing under vacumme. under boost conditions ill be letting out all the air in the valve cover. to me it seems fully functional plus i wont have oil in my intercooler piping and eliminated another boost leak spot.

The problem with your setup is that there is no point for air to ENTER the crankcase. You're drawing the air out and have nothing to replace it with, so you'll get rediculous vacuum and start pulling air past your rings and other seals. I doubt that would actually happen, but that's the basic idea. Its not really vented unless there's a place for fresh air to get in.

The diagram 99gst posted up the last page is the setup I'm using. It works excellent, its what RRE personally recommended to me, and it leaves no oily residue anywhere in the engine bay, that's what the catch can is for. This is the setup I've seen every high powered Supra, RX-7, 300Zx, etc running. I'm assuming they know what they're doing.

 

[dnhieu]

i thought that under any conditions (boost/vacumme) you wanted the air drawn out of the crank case...

im confused...

 

[dnhieu]

The problem with your setup is that there is no point for air to ENTER the crankcase. You're drawing the air out and have nothing to replace it with, so you'll get rediculous vacuum and start pulling air past your rings and other seals. I doubt that would actually happen, but that's the basic idea. Its not really vented unless there's a place for fresh air to get in.

okay i completly get what your saying man but this guys statement is telling me that you need some crank pressure, and your telling me the less crank pressure the better!


so what is it?

also what are the downsides to running no pcv valve? obviously its only going to affect my car in vacumme. when i had it set up like everyone (venting it in the air) my car idled like crap and stalled all the time! since i swtched back it idles alot better but i switched the pcv valve with a used one that doesnt leak quite as bad. before with the old pcv it would would idle really bad and stall everyonce in awhile...

 

[MyBeatGSX]

You aren't likely to EVER have too much vacuum in the crankcase, case in point, Angelle Seeling's (now Savoie) P/S bike had at one point three electric vacuum pumps, 'till NHRA rules prohibited that many, so her team just used larger ones & thats on a 1500cc engine for only 7 seconds!

Yea exactly. That's an engine only run at WOT for 7 seconds. Not an engine that could sit and idle in traffic for 20 minutes with extremely little blow by to add any air back in.

Think of it this way. Hook a vacuum pump up to an empty soda can. What happens after all the air comes out? The can colapses, what happens after that? Leave it hooked up long enough and you'll blow a hole in the side of it to let air in. Obviously that's an exaggeration, but you can't keep sucking air out of something without having somewhere that something to replace it can get in.

If your sucking air out of the crankcase, you need something to replace it with. That's why people have breather filters/hoses. Don't confuse the stupid high vacuum used for ring seal on stupid high RPM race cars, with the emissions only PCV valve in our cars. The purpose of PCV is to circulate fresh air through the crankcase and suck out all the blowby gases to have them be burned and catalyzed (sp?), same thing I said the first time. The "breather" hose is a fresh air IN hose. It is NOT a vent hose, when you're running retarded boost and your rings suck, it will become a vent hose, but that's not its primary purpose. Its there for the reason I already stated. This is why just replacing it with a breather filter creates an unmetered air leak.

PCV does not help ring seal, as you even pointed out yourself, it only works for that when you don't need it. So unless you have a purpose built race car and no better way to make power, don't bother trying to make vacuum in the crankcase at WOT, its not going to happen.

If you're having problems with how your car runs with no PCV, you have bigger or unrelated problems. Removing the PCV should have no effect on idle quality, if anything it should be better because the mixture will be cleaner. Did you remember to plug the nipple in the manifold that the PCV line connected to? doh!

 

[dnhieu]

yes i did plug the whole and i boost leak tested it after wards and no leaks from the hole i pluged

anyways is the the way with the breather filter on top going to draw CLEAN air back in when its always blowing back out? i mean there is oil on the filter for a reason because its BLOWING AIR OUT!

 

[Sivad87]

this thread so turned into bench racing PCV valves

next up, EGR, exhaust pipe size, and catalitic converters

 

[1stGenRocks]

Think of it this way. Hook a vacuum pump up to an empty soda can. What happens after all the air comes out? The can colapses, what happens after that? Leave it hooked up long enough and you'll blow a hole in the side of it to let air in. Obviously that's an exaggeration, but you can't keep sucking air out of something without having somewhere that something to replace it can get in.

your missing the point. Your never going to get enough vac to cause a problem but you will get all the blowby gases out. And as a added benefit you never have to worry about the pcv valve leakign under boost again.

Your soda can example isn't quite right. You forgot about the blowby from the rings. Even in a good engine there will always be some blowby. As long as you get the blowby drawn out you dont need fresh air. The closer to vacuum the crankcase is the less friction on the rotating assembly and the better the rings will seal.

Theorieticaly you need to let air in to get air out but the goal is to get as close to vacuum as possible.

Even on a proper functioning stock setup the intake hose becomes a vent under boost. While your boosting the pcv valve is shut and your getting the most bloyby so the pressure goes out the intake hose and oil coats everything.

 

[dnhieu]

your missing the point. Your never going to get enough vac to cause a problem but you will get all the blowby gases out. And as a added benefit you never have to worry about the pcv valve leakign under boost again.

Your soda can example isn't quite right. You forgot about the blowby from the rings. Even in a good engine there will always be some blowby. As long as you get the blowby drawn out you dont need fresh air. The closer to vacuum the crankcase is the less friction on the rotating assembly and the better the rings will seal.

Theorieticaly you need to let air in to get air out but the goal is to get as close to vacuum as possible.

Even on a proper functioning stock setup the intake hose becomes a vent under boost. While your boosting the pcv valve is shut and your getting the most bloyby so the pressure goes out the intake hose and oil coats everything.

this has been the answer i have been waiting for! i know im not going to draw enough vacumme to suck up all the air in the crank case but if i can get it to idle normal, drive normal, pull more air out under boost then before, eliminate a boost leak spot, and not hurt anything in the process i will be happy. i mean that was the whole purpose of this thread to begin with! maybe i should convert everything to 10AN lines. the bigger the lines the more air i draw correct?