Synjn

iTrader: (1)

Well actually about 5 days ago I drilled out the pcv and ran my current setup as shown, minus the removal of the crossover, and drove around for 10min. That's when my car looked like a James Bond smoke screen out the back.

Today, I removed the crossover tube and the same thing happened. Not as bad though. Although today I didn't actually drive the car around. Didnt want to do that to my car again. Today only had the car running 30 sec with the drill out pcv and pulled back the plenum hose to find oil making its way into the manifold.

So either way, using the drilled out pcv was dumping oil into my manifold. Now why is the question?

Im getting less vacuum in the catch can with the drilled out pcv. 7 in/hg as opposed to 15 in/hg, but i'm getting more airflow. More volume. Also, I have two breathers on the driver side letting air in contributing to the increased airflow.

Furthermore, correct me if i'm wrong, but we dont want a ton of vacuum under low load conditions anyway. The pcv acts as a regulator to prevent too much air passing through.

Who's using a drilled out pcv? I want to see their setup.

I completely agree...So why is everyone saying that a vacuum source will unlock hp? Unless you're using a mechanical vacuum (which is super strong), you're not getting any better piston ring seal than you would with a regular open breather setup. 0 psi.
Maybe at idle you'd make more hp, but whats the point in that?

Synjn

iTrader: (1)

You mean putting the breather directly on the drilled out pcv? For the past 4 days i've been driving around quite a bit, boosting, with that exact setup. Only I removed the center crossover and put breathers on them also. Four total. Effectively doubling my crankcase evac potential.

Smells a bit. I noticed immediately after shutdown & taking off my oil cap, vapor accumulating under there. Makes sense, I got not flow pulling that crap out.

Back to square 1

My thinking: Nissan didn't design this engine for boosted application. So first things first, increasing the CC evac potential first and foremost. Under boost we want the crankcase as close to 0psi as possible. Some people are drilling new holes in the valvecovers. I wanted to avoid this so i'm using the vents already there.

I see people welding huge barbs on the valve cover, using huge tubing running to all kinds of catch cans, then closed loop back to the plenum. They say, "i'm getting very little oil in my catch so it must be working." Well the reason is because the length in the tubing and catch cans is causing airflow restriction. Just like the oem pcv does? Just putting themselves back to 15 in/hg. Like I said the oem pcv will do the same thing.

Try this: take two pieces of say 3/8 tubing. one 6" long and one 24" long. Try to breathe through both of them. The difference is quite dramatic.

You dont need nor want large volumes of air being pulled from the valve covers at idle. You'll run into lubrcation problems at the top end. If we could pull solely from the bottom, pull as much as you want it won't effect anything upstairs.

Matter of fact, when I was using my drilled out pcv, with my short length tubing as I've shown. The pressure dropped from 15in/hg to 7in/hg yes...but I also was hearing this strange winding sound coming from the pass side valvetrain. The same EXACT sound that I toiled over in my old 350z and found it was due to low oil levels. Sounded like a plastic spindle spinning loosely around a shaft - if that makes sense. Found out I had less than 2 qts in my engine. Adding oil got rid of the sound. Sold the car immediately.

conclusion: drilled out pcv = drop in vacuum @ the catch can = increased airflow = starving my valvetrain of oil on passenger side.

I think there is a little bit of genius built in that oem pcv.

Show me someone using a drilled out pcv or even a welded 1/2" barb, on short tubing, going straight to the plenum.

streetzlegend

iTrader: (2)

I dont see an issue with vapors flying around in the VC after engine is shut off. The goal is to eliminate pressure buildup, and will all ports open, that shouldnt be a problem. I did however drill an additional 1/2" hole on one of the VC to further eliminate pressure buildup, works perfectly.

midz350

iTrader: (4)

Wouldn't using both of the pre-turbo pipes would pull more vacuum?

Synjn

iTrader: (1)

Both? I only have one supercharger hooked up right now. lol
You running twins i assume.

The answer is no. Not even close. That BS is pointless, unless you work for greenpeace save the planet.

That port, so i've read,will only pull 1 in/hg (.5psi) And thats at wot. At idle it pulls nothing. And we know our crankcase boosts closer to 5psi. So it isnt doing sh!^.

It's for emmisions. From what the data tells me.

Synjn

iTrader: (1)

Well according to the experts those vapors are a mixture of fuel, water, C02, and sludge. Over time can contaminate your oil.

I am curious. Which VC did you drill? And what did you attach to that port? AND what do you mean "works perfectly?" Whats the evidence of that? What prompted you to think it was broken?

Synjn

iTrader: (1)

This is wrong. That tube going from your catch can to your air filter is a huge vacuum leak. That is where your unmetered air is coming from.

I dont know the length of your tubing but that hole at your air filter, air is not going in, it's traveling outward right into your plenum. Intake plenum is much stronger vacuum.

I understand what you were thinking though. If the plenum and intake were of equal vacuum at all time, your setup would be ok. Although I dont like the long tubing, which is probably minimizing the ill effect of the design flaw.

Plug that hole.

binder

iTrader: (8)

how is he pulling in unmetered air?

if that hose goes to the intake between the maf sensor and filter then it's metered air. Now if he puts it between the maf and the throttle body it would be unmetered air.

forced_04

iTrader: (1)

WTFFFFFFFFFFF


this thread confuses me a lot, everyone seems to be dis-proving everyone else set-ups and I cant tell who's right and wrong!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!


Hal is always a good reference (hint hint wink wink nudge nudge)



Question... How would I go about actually logging the pressures and being able to test and tune persay a catch can set-up?

Synjn

iTrader: (1)

So we only have 2 vacuum sources:

1: plenum (strong) 15 in/hg
2: pre-boost port (very very weak) 1 in/hg

At idle:
The arrow in the picture is pointing the wrong direction. The plenum is the dominate vacuum source, realistically the only source because "pre-boost vacuum port" produces no vacuum at idle as we have discussed; Here the plenum is pulling from the catch can and the "pre-boost vacuum port"

The air being pulled by the plenum from both of these sources is technically unmetered, but chances are his car was tuned or definately came from factory with the intake plenum recirculation intact. By adding the hose from the catch can to the "pre-boost vacuum port" is allowing fresh air to come from the "pre-boost vacuum port" directly into the plenum. Which is unmetered and wrong.

Yes air is traveling up through the TB, but the cutout designed to create a vacuum there is being overpowered by the plenum. So the "pre-boost vacuum port" is what i like to call it, doesnt have enough power to pull through the catch can, plenum, and valve cover as illustrated.



I hope that makes sense.

Also if his check valve is located at the top right coming out of the valve cover, during boost conditions air will be moving out the plenum right past the catch and out the "pre-boost vacuum port". Assuming he's FI'd

See what i mean?

Synjn

iTrader: (1)

I'm doing it right now... I'm using my Dad's old school sh!^ Speakin of which I could use his input. He's got degrees in both mechanical and electrical engineering.



http://www.diyefi.org/forum/viewtopic.php?f=24&t=357 <------Read this there is more to the pcv than meets the eye.

Engine off/backfire --- Low load/Idle --- Medium Load/cruising --- High load/WOT
0 /positive pressure---Highest Vacuum--- Moderate Vacuum ---- Slight Vacuum
PCV Valve closed ---- PCV open slightly-- Valve opens more --- Open all the way

The first line shows load, second line pressures seen in the Intake manifold, and third line is how the PCV valve responds.

streetzlegend

iTrader: (2)

In theory, perhaps yes, those vapors will contaminate the oil, however realistically I dont know if it applies (unless you have very long oil change intervals). None of my oil analysis have shown any sign of contamination, but they have only been about 2k miles intervals, maybe with 4k+ it will be a difference. Side note: I had this same vented setup on my VQ30 for 3 years, with much longer oil change intervals and the engine also had about 160k miles, turbo charged all that time, zero sludge, so clean you can eat off the cams.

I have a fwd vq35, drilled the VC with the oil cap. I posted a pic in this thread I believe(My post tend to get ignored often, maybe its my post count ). I just put a mini filter on it (very very little oil comes out), but I will be making a small vented Can soon so that I can run a hose from there to the can.

I was having a good amount of oil leaking out of the inner timing cover, and then it hit me, there must have been too much pressure building up in there. I also hooked up a boost gauge I had lying around to one of the outlets (one that connects both VC together) and had some pressure build up, vs. having my new 1/2" hole, which had zero pressure. Dont remember exactly how much pressure it was building up, but more than zero is not good.

After doing this, it went from having oil all over the timing area including alternator, to having zero oil leaks.


Edit:
could have sworn I posted the pic, but here it is:

Synjn

iTrader: (1)

1: Are you boosted?
2: Same setup as who?
3: What are you connecting to that giant barb?
4: Where is the line going from the oil cap going?
5: Are you running manifold recirculation? Any lines going back to going back to any kind of vacuum source?
6: How much pressure were you logging aprox, with what plumming setup. Some comparisons?

Tell me more.

If you drilled out the oil cap on the driver side, why didnt you put the barb on the pass side to even things out?

rcdash

iTrader: (18)

You will gain an uber reliable port for cc ventilation. You do not want to hook it directly to the manifold as synjn warns against. You'll just pull oil right out. Use a catch can and check valve and 3/8" tubing and it will create enough pull to evacuate gases during low load/idle but enough resistance to keep the oil accumulation to a minimum. It helps if you have a breather on the opposite port to prevent vacuum from getting too high in the cc. The plenum vacuum would much rather pull air with light fuel and water vapor rather than the oil. That's the whole point of positive crankcase ventilation.

NONE OF THE CRAP IN THIS THREAD IS TO GAIN HORSEPOWER. It is to minimize crankcase pressure (to prevent oil seals from leaking, dip stick popping out, etc) and if done right, minimize the smell associated with an open breather (by using the breather to allow fresh air in, predominantly). If you don't care about the smell and you don't care about blow by gases contaminating the oil over time, just put an open breather on both ports and you'll be all set.

This is my setup and it has worked well to prevent oil in the IC piping and smoke out the exhaust. I have no smell at idle (I do have a HEPA filter with activated charcoal in my car though). I have my center nipples connecting valve covers connected. I have a sponge inside the catch can. The t-fitting coming out of the catch can has 5/8" hose nipple to connect to the turbo side intake and a 3/8" nipple to connect to the intake manifold and a 1/2" nipple going to the catch can. My drilled out PCV has a 3/8" to 1/2" right angle fitting. So the catch can has 1/2" heater hose going in and out.



If I were to get rid of the turbo side intake draw, I might keep the T fitting and check valve open to air just to make sure it never exceeds 0 psi on the passenger side. With the sponge in the catch can, I don't think I'd need a breather.

streetzlegend

iTrader: (2)

1. Single turbo HX40 @ 15-17psi (Built short block)
2. I didnt mention I had the same setup as anyone. I was mentioning how my previous engine was set up. I have a 97 Maxima.
3. The big barb you see in the pic currently has a little filter on it.
4. The line going into the oil cap is the turbo's oil return (rear mount turbo setup)
5. There are zero lines going back into the intake manifold. the crank case is completely vented, all ports are open.
6. As mentioned I dont remember how much pressure the crank case was building up, when I tested it both valve covers were vented as I have it now, without the big barb there was some pressure building up, once I put the barb it eliminated it. Again, i did not write anything down, I was just doing it at a moments thing.
In my opinion there is no need to even anything out, both heads and crankcase are all connected, so it wont make a difference if I have all vents in one side vs. having even openings on both. In addition, my intake manifold blocks the rear valve cover completely.

Synjn

iTrader: (1)

Rcdash is correct. NONE OF THE CRAP IN THIS THREAD IS TO GAIN HORSEPOWER.



These guys are doing it,

http://nutterracingengines.com/racin...uum_facts.html

But they are managing to create serious vacuum at wot using secondary pumps and motors. Thus counter acting windage loss when it's at its greatest.
Since we dont have such a radical setup, the best we can do is generously open up the valve covers to release the crankcase pressure and shoot for 0 psi in the crankcase as RCdash said earlier. Which... actually... would help reduce windage loss to a certain degree if you are currently using the stock 350z CC venting, which is agreeably way too restrictive. But nothing you would notice performance wise.

Thanks for the diagram Dash! I subscribe to your setup as well. Proly the only one on this thread, other than mine of course. which has yet to be logged and tested.

More info to come.


This stuff can get complicated...

jumbosrule

There are a bunch of ways to run catch cans and most of them work just fine - especially at NA. If you are boosted it is more important to install certain ways.

A lot of people learning about catch cans. Here's a really good catch can manufacturer and site - check out the FAQs to learn about the purpose of the catch can:

http://www.saikoumichi.com/faqs_page.html

These cans are awesome because the mfg will customize the fittings and style to your exact application for no extra charge. I did a lot of research on catch cans before I bought mine.

You didn't have to drill out the PCV either but opening it up insures less restriction at the Valve cover exits. If you drilled out one, I would go ahead and drill out the other.

Just an FYI - You also have a hose that runs between the two valve covers under the plenum. You can see it if you look just past the crank case under the center of the plenum. This hose connects the two valve covers to make sure they are at the same pressure on both sides. Along the same lines as drilling out the PCV and breather hole, you could drill out the fittings and attach a larger hose to make sure pressure equalizes quickly and is not restricted when flowing between the two.

Don't really agree with this. A breather provides zero suction where as a hose connected to your intake BEFORE the turbo would provide constant suction.

There are applications where breathers make more sense, depending on how your catch can works. How does your can catch the blow-by products? Does it use a screen, mesh, a baffle or gravity?

A length of tubing just adds a small volume of area to the crankcase. It is not greater effort for pressure to escape because you have a suction/vacuum line attached. If you are using a breather instead of a suction line and you have restrictive flow into the hose, then pressure flow might not be ideal which is why you would want to drill out the hose fitting to be as large as possible.

+1.

If NA, hook it anywhere in the charge pipe before the Throttle Body.

If boosted, you don't want to pressurize the suction line - that would reverse flow into the crankcase and since you have drilled out your PCV which acts like a check valve, that would be bad.

Some people think they can route the catch can back into the oil pan. Definitely don't do this. As posted before, there is more than just oil in that blow-by. Here is a photo of what my catch can emptied out after four months. Nasty.

binder

iTrader: (8)

I just have breathers on them right now and that's all i want to ever do. So I would be ok with drilling out the pcv valve if i have just a breather, correct? the whole worry about driling it out is only for those applying a vac source to it in which they just need to add their own check valve.

I personally am sick of all the stuff in this engine bay as it is so i'm trying to keep it light.

and yes, i have a small catch can and it has nasty stuff like that in it (catch can right at my breather for my valve cover). I think moisture is getting in there from being open with a breather because when i had it as a closed system back to the plenum it never had brown or white (from oil and water mixing)

streetzlegend

iTrader: (2)

There are so many ways of hooking up cc ventilation system, no matter how you do it, the main goal = get pressure out of the case. Heres another idea (another curve ball into the thread). Exhaust Crankcase Evacuation! lol

jumbosrule

Yeah, you should be ok. If the filters on your breathers become quickly soaked with oil, you'll see it and smell it. It means the blow by gasses are not collecting in the can and will clog up the breather filter and make a mess. Not a big deal if you keep an eye on it, but you could go through a lot of breathers. Using a better catch can could fix that - or stuffing the one you have with baffle material (a metal pot scrubber works) to give the blow by gasses a surface area to collect on.

I don't think moisture enters the system through the breather - not enough to see anyway. That would mean that (wet) air is flowing backwards into your can towards valve covers. Much more likely is that you are catching coolant. A little is normal. A lot of coolant could mean a bad head gasket or even worse a crack in the heads.

Blow by gasses are oil, coolant, unburned air&fuel mixture and even a little bit of exhaust gas, which contains burned fuel (carbon). If your can can't separate the air from the contaminants, they will collect on or pass through your breather.

Any form of crankcase ventilation that is not sucked back into the plenum and burned is not emissions legal and won't pass inspection. Breathers are never emissions legal except on older exempt cars.