JDS Performance

Awesome....

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ForeignMuscle

Lol, whatever works. I'm sure when I first started welding mine weren't much better. Looks like mig maybe?

Matej

Does the PCV valve actually do anything special, or is it basically just another valve cover vent?
I do not see how it could do anything different from a regular valve cover port, other than close under pressure.

Which leads me to my question.
Instead of adding a port to the top of the valve cover, why not just replace the PCV valve with a straight-through fitting and run a vacuum line from it through a catch can into the intake?
Possibly cut off the PCV 'strainer' on the bottom of the baffle, so it does not suck in extra oil. Maybe plug it and drill holes in the baffle instead.

Of course, the T-fitting would be replaced with a single-end fitting routed to the crankcase vent, same as when adding a port to the top.
The opening in the valve cover for the PCV valve is larger than necessary to satisfy any vacuum hose diameter desired.

jr_ss

Yeah, it's pretty much a one way check valve. It keeps your crank case from seeing positive pressure under open throttle conditions and helps add negative pressure at idle.

Easiest option is to route it through a catch can back to the turbo inlet pipe.

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Kingtal0n

When the engine goes into boost the pressure will be allowed into the valve cover from the intake manifold. Oil will go everywhere, blow-by will be significant, the engine will not run like that for long.

There is a reason that valve is one-way.

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Matej

It would be routed to the intake before the turbo. Basically just used as the main valve cover vacuum by replacing it with a larger fitting.


I like how on the VE the vent is hidden in the back.
Since this motor will be NA, would it be alright to route the vent through a catch can directly to the intake manifold, and just plug the PCV?

Kingtal0n

Are you talking about running a vacuum line from the intake manifold directly to the inlet for the turbocharger? That completely bypasses the crankcase, which would be pointless. The whole point of the system is to give a "positive" ventilation to the crankcase. During vacuum, it comes from the intake manifold. During boost, it comes from the inlet of the turbo. You know this already, what I am trying to figure out is how you are trying to change it around. The vacuum source is already very weak during boost, the closer to the crankcase, the shorter the line, the better. Catch can setups are a great idea in theory but to work they need to be 100% sealed up, with short plumbing of the appropriate size, and who decides what is appropriate?

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jr_ss

I don't see how that would cause an issue. An NA motor is under constant vacuum as it is.

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metako42

I still have the factory breather hose routing with factory oil/air seperator (low mount GT2871). I need to keep it looking as factory as possible here (Australia) to avoid getting a defect notice if pulled over. Car sees only street use at this stage.

Would it be an improvement on the factory routing if I:
-connected the hose from the PCV valve to a catch can then intake pipe (should I delete the PCV valve and run a straight-thru fitting here?)
-blocked off the inlet to the intake manifold
-left the std hose going from cankcase to std oil seperator to rear T connector on cam cover
-blocked off front connector on T

So instead of welding a bung on the top/rear of the cover I use the PCV valve outlet for this purpose, and leave the crankcase hose going through the factory seperator to the T. Is the intake pipe a better source of vacuum than the intake manifold at idle and off boost?

metako42

I've been thinking about this a bit more and since no-one has reponded yet I think I have the answer to my own question.

1. some people here have already blocked off their PCV valve from the intake mani and have found no ill effects. This means that the vacuum from the intake pipe feeding the turbo alone when off boost is probably adequate

2. off boost, the PCV valve exit position already provides adequate scavenging of the crankcase in the factory system

3. off boost, the vacuum from the intake pipe has the exact same vacuum as the intake manifold as its generated by the same source ie the pistons. It will be only a little less due to the fact that the turbo and IC pipes and intercooler will present some restriction. A boost/vacuum guage could be connected to one of the vacuum hose fittings going into the intake pipe to compare its vacuum to the IM vacuum

4. on boost, will the PCV valve exit postion provide adequate scavenging of the crankcase? Still not sure about this one. Its in a simllar position to the slider2828 mod only on the other side of the cover and on the side not on top

5. as a further way of using the existing factory gear, for those wanting to keep it stock looking, the hose from the crankcase could be routed straight to the T in the cover, bypassing the factory oil seperator, and the seperator could be used as a catch can between the PCV valve and the intake pipe

Attached Images

modified factory system jpg.jpg (28.1 KB, 62 views)

cotbu

It's clear you don't understand the system, unless you just mistyped some thoughts or something.
The system is very simple, and you could improve on its design, but that diagram is fail!
The only mod I would suggest for an OEM setup on the PCV side is a catch can.
Also, N/A vehicles aren't under constant vacuum.

Why do you want to eliminate the PCV system?

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jr_ss

How do you think NA vehicles fill the cylinders? Granted there is atmospheric pressure playing a roll, but the piston pulls/sucks air into the engine, aka vacuum.

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cotbu

Did you not type this statement?
Well if you did? I typed this!

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metako42

mmm...I think you're answering Jr_ss and not me but id like to eliminate the pcv because I haven't found one yet that doesn't leak boost, needs a check valve and also needs an extra catch can and associated hosing. Also to avoid welding that extra bung in the top of the cam cover.

Cotbu, are you saying my diagram is a fail?

jr_ss

I typed that statement sir. Not the gentleman that drew the diagram.

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Matej

That is basically what I was suggesting.
Of course, in your diagram the other side of the T would need to be capped off (I am guessing that is what the X means), and the PCV valve should be replaced with a larger diameter straight-through fitting. I would also suggest cutting the PCV 'strainer' on the valve cover baffle shorter so it does not suck in unnecessary oil, or possibly blocking it off and drilling holes in the baffle instead.

I do not see why it would not work, unless the PCV valve has something magical inside that I am not aware of, making it different from a regular vacuum port sucking fumes and pressure out of the head.

Not sure about using the factory oil separator as a catch can before the intake, but I do not know much about it.

cotbu

This is a reply to the post above it!
this is called a statement, it came in mid thought so I typed it. It's for everyone, but the poster jr_ss replied.
This is a question for you metako42
Now let's talk about the pcv system and it's ability to prevent backfires and such.

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Matej

Please do elaborate on the SR PCV system, as I really do not see its point with another vacuum present on the valve cover, but I am probably missing something.

I am guessing it may have something to do with how it is routed directly to the intake runners?
However, most aftermarket manifolds do not even utilize it and people just end up connecting it to a vacuum port on the manifold.

cotbu

All it needs is a manifold vacuum source. It's a simple design, you guys just need to know what it does and why it's there. Google it or something, the first part of this thread makes the system better. Do it or not! completely eliminating the system or killing make no sense to me.

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ForeignMuscle

My pcv has never leaked boost.. Neither have the ones owned by all the posters in this thread.

The system in this thread works flawless. If you have an issue welding an extra bung on your valve cover then it must not be that important to you. Why try inventing something new when there is already a proven method for scavenging gasses from the crankcase?

Just leave it factory or use the Blu808 mod. You are really wasting your time and overthinking this whole setup..

Matej

From reading about it, it seems that generally the crankcase vent tube is considered a part of the PCV system. The main part actually. The PCV valve's only job is to provide vacuum for it and keep pressure out, and on some motors it helps filter contaminants.
However, on the SR we already provide vacuum for the crankcase breather by connecting the valve cover to the intake, and we filter contaminants by using a catch can, which is basically what a PCV system is. So what we consider the PCV on our motors (the PCV valve) is pretty much useless, as far as I can understand. Plus on boosted motors it only functions in idle, and even if it helps filter anything, it would still be sucked out through the vacuum to the catch can (a stock SR does not even use a catch can between the valve cover and intake), so I still do not see the point of it.

metako42

Slider 2828 has already recommended the pcv be attached to the intake pipe via a catch can (see my quote above). So it's not such a big leap to use the pcv outlet as the main source of crankcase ventilation for those that don't want to or can't weld a bung on the top of the cam cover.

Unless I'm mistaken, the S14 cam cover uses a side outlet for the connection to the intake pipe and this is considered to be a good system, only it's on the other side of the cover to the PCV.

Just give us rational reasons that this would not work, not emotional ones. For example I've realised my suggestion to use the factory oil seperator as a catch can for the PCV would not work because there is no way to drain it of oil if you use the bottom inlet for the PCV inlet and the top outlet for the hose to the intake pipe. So stike that out for a start.

Foreignmuscle: if you've tested your PCVs with a boost leak tester and never had one leak then either you are very lucky or I am very unlucky. Countless people will tell you that many of these valves leak even from new. I'm talking about the S13 OEM metal type.

metako42

The first routing below is with the oil seperator in line with the crankcase breather and the second is without-if you have room for the seperator I can't see a reason not to use it, as it would make the job of the catch can on the intake hose easier.

Attached Images

	S13 oil hose routing-final option 4b.jpg (33.8 KB, 56 views)
	S13 oil hose routing-final option 5.jpg (33.0 KB, 55 views)

metako42

Been learning a bit more about PCV valves and it looks like it's not a good idea to delete the PCV valve or route it to the intake pipe.

Crankcase ventilation system - Wikipedia, the free encyclopedia

As the PCV valve closes DOWN when there is high vacuum (at idle in the std system/position) because there is minimum blowby at idle, if it was routed to the intake pipe then as boost and blowby increased the valve would close down more and more - not what you want.

If the PCV valve was deleted and a straight-thru fitting was used instead to connect to the intake pipe then you might get too much scavenging at idle and other off-boost situations. It might work but would take alot of work to figure out how much scavenging you needed and were getting-not something I could be bothered with at this stage and I wouldn't want to risk damaging my engine not doing this.

So I'll be going back to the std routing below with a catch can on the PCV to intake manifold hose (with check valve added) and another catch can on the T to intake manifod hose (maybe with check valve added there too so that when it's off-boost and the PCV valve is open and sucking air from the T that it only sucks from the crankcase hose and not the catch can on the intake pipe hose).

The slider2828/blue808 mod seems like an excellent mod if you can do it so I'm not taking anything away from them for a moment but since I only use my car on the street I probably don't need it that much either.

(Mmm...maybe I could weld a bung on the REAR of the cam cover instead of the top and hide it that way...)

Attached Images

S13 oil hose routing-final with 2 catch cans 2.jpg (40.1 KB, 48 views)

ForeignMuscle

I'm not sure if this problem has been addressed previously or not, but this setup can cause a slight problem if you use a top mount setup. Mazworx, DOC Race, Hybrid Dynamics, and Peak Boost are all nearly identical. The hose end that connects to the side bung on the valve cover will hit the turbine housing. (-10 90* hose end in my case, but a -8 will not fit either) There is a pretty easy fix to this problem and it actually comes out to the same price.

Instead of welding a male AN bung to the side of the valve cover, weld a female 1/2"NPT bung (JOES Racing Products makes one that is very low profile) and use a 90* male 1/2"NPT to male -10AN fitting. Then you will use a straight -10 hose end which will be pointed directly towards the rear of the engine, straight towards the oil sump return.

I'll post some pictures when I am finished with the welding.

jr_ss

A 90* won't fit, however a 120* or 150* will clear because of the tighter radius. It also gets your hose closer to the VC and farther away from the heat source.

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ForeignMuscle

Jr, no matter the angle, the distance from the bung to the farthest point on the hose end is nearly the same. It really only changes the direction your hose takes. Your valve cover is not the same as us with the det. Your fitting is around the compressor area where ours is around the turbine side. Your setup looks good though. Thanks for looking out.

jr_ss

Hmmm, must be S13 DET? I had the same setup on my S14 DET without issues...

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ForeignMuscle

Ahh, you are correct. I forgot the s14/15 was different.

Hey I've been meaning to ask you if it's possible to use a vvl head with a factory ecu if you use the cam angle sensor... You can pm me so I don't clutter this thread.

silviaNC

Any member here selling/making the s13.4 valve covers?