I am in the process of getting a spare plenum powdercoated and was wandering if deleting the pcv valves was as simple as plugging the holes on the plenum, removing the associated pipework and venting the crankcase/camcovers to atmospere using new hoses and a breather filter or two...... or am I missing something and its not that easy?.

You still need to vent crankcase pressure mate, so that's when you go for a catch tank. Not a trivial thing to get right either. I plan on doing it to mine eventually though, on the new engine, so feel free to pave the way and let me know how 'easy' it was ;)

I was looking at this and figured you plug the holes in the plenum each side. I have seen pictures of the metal pipes that comes out of the valve covers and turn 90 degrees to face the front of the car, in the pictures these had been turned 180 degrees so they faced back toward the bulkhead, which would make it alot easier to plumb into the catch tank.

 

Then chose a side for a catch tank. Plum both the breathers into the catch tank, one pipe obviously being longer than the other depending which side you can fit the catch tank.

 

Maybe someone that has done it can give more info

been looking at this right up on another forum for a scooby that might be of use

 

http://www.scoobynet.com/technical-topics-archive-427/765245-newage-oil-catch-tank-can-install.html

been looking at this right up on another forum for a scooby that might be of use

 

http://www.scoobynet.com/technical-topics-archive-427/765245-newage-oil-catch-tank-can-install.html

 

That system recirculates the air back into the intake system as a sealed system. Wouldn't it be better to have a vented system with a catch tank that has a breather on to vent to atmosphere?

 

The gases it's venting are hot combustion blow-by gases so i'd have thought not putting them back into the intake would be better?

 

Something I just thought of...... Q. If the car runs a MAF as standard, then having a crank case vent that allows air into the intake but after the MAF would mean that there is unmetered air being put into the system, wouldn't the engine run better without it?

That system recirculates the air back into the intake system as a sealed system. Wouldn't it be better to have a vented system with a catch tank that has a breather on to vent to atmosphere?

 

The gases it's venting are hot combustion blow-by gases so i'd have thought not putting them back into the intake would be better?

 

Something I just thought of...... Q. If the car runs a MAF as standard, then having a crank case vent that allows air into the intake but after the MAF would mean that there is unmetered air being put into the system, wouldn't the engine run better without it?

 

Technically yes and technically no, lol.

Technically yes and technically no, lol.

 

Please elaborate geek:tt2:

Well technically the air from the crank case came from somewhere, and in some cases from the intake, what isn't so good, is that it's no longer uncontaminated. The air filter does a lot to filter out damaging particles from the air going into the system, the down side to both EGR and PCV valves, is that the air inside them is no longer uncontaminated.

 

You've now got Nitrogen Oxide (Amongst other things) in the EGR and you've got oil vapours in the PCV, you also get oil spat into the intake from the PCV, which is both a good and a bad thing. As the engine gets older, a bit of oil in the cylinders is not that bad of a thing, as it can help to seal the pistons and prevent blow by, but oil in the intake makes it dirty and less efficient, plus of course oil in the cylinders is a bad thing if you get too much in there, it can reduce the spark from the plugs, it also contaminates what's in the A/F/R inside the cylinder etc.

 

The EGR actually helps towards lowering the cylinder operating temperatures too, as Nitrogen Oxide burns cooler than Oxygen does, so this can help prolong the life of your engine, in theory at least. There are ups and downs to both systems, which is why they're fitted as standard. The general consensus seems to be that deleting the EGR is a good thing, and I'd agree, whilst some of the benefits of the system are lost, you'll get better fuel economy and a cleaner burning system, even if the cylinder temps go up and the emissions with it. Deleting the PCVs is a little more complicated and with less benefits to doing so if not done right, can shag your engine right up, as I do believe a couple of people on here have experienced first hand before now?

There's a thread in advanced tuning under 'crankcase pressure' by silverbullit. he's done it and a few others on there. ill be doing this later in the year. most turbo cars running higher boost use oil catch tanks. the standard setup isn't up to handing the extra blow by and as said, the intake charge isn't clean and running higher boost you'll run a higher risk of det.

not an expert, just the way it was explained to my by an expert while on a rolling road.

Hope this helps.

cheers

Danny

Edited January 7, 201214 yr by keano
predicitve text on my phone

Cheers HP, I understand all of that except what you're saying about nitrogen oxide from the EGR being good for cooling the cylinder temps. I thought you were looking at a temp close to 1000 degrees for combustion gases when giving it some beans, which wouldn't be good to recirculate back in or am I misunderstanding?

 

Cheers for that Keano, here's the link for anyone that reads this thread. Read it, it's informative

http://www.300zx.co.uk/forums/showthread.php?t=123979

 

Look at post #59. You see where he has blanked off on the right of the diagram, I can't remember 100% but im sure that there are the same pipes coming out the rocker cover on the other side of the engine as well? Are these blanked off or plumbed in with a T piece to the pipe running past that side? See what I mean, in my head it makes sense to mirror both sides or as it's all connected internally is what's in the diagram ample?

 

Hypothetical question: Instead of running a catch tank and having the smells that come from it or having pipes dripping on the road/track or firing out the back. Would it be possible to plumb it into the exhaust? I know it would be hassle as you would have to drill and weld a connection in but would it be an option or would exhaust pressure blow back up the pipe? Might not be a good idea for a road car if it's subjected to an MOT emission test?

I vented mine to atmosphere no catch tank involved. Running at 14PSI of boost and no sign of pre-detting whatsoever. The thread Silverbullet started is what I went on and altered his ideas to suit my needs.

My PCV valves were blocked so the car ran alot better after I by-passed them, I really dont like the idea of my engine getting recycled gases instead of nice clean air :p

I vented mine to atmosphere no catch tank involved.

 

Thats what I was thinking.........on my 3.0 v6 Calibra I blocked the breather connection on the inlet manifold and ran the crankcase breather to atmosphere with a breather filter on the end and had no problems at all, in fact it seemed better cos hot dirty air wasnt going back through the inlet system.

 

Surely as long as the crankcase is vented adequatly there shouldnt be a problem?.

There shouldn't be a problem, but the higher the boost and the more blow by you have etc. the more oil is going to get pushed out of your vent. I personally wouldn't vent it to atmosphere, I'd vent it to a catch tank, albeit one with a vent.

There shouldn't be a problem, but the higher the boost and the more blow by you have etc. the more oil is going to get pushed out of your vent. I personally wouldn't vent it to atmosphere, I'd vent it to a catch tank, albeit one with a vent.

 

Dont catchtanks ultimately vent to atmosphere anyway?, and if boost pressure is getting into the crankcase to raise crankcase pressure you've got problems anyway.

 

I had a sticking pcv valve when I first got the zed and the crankcase was pressurising on boost.if the crankcase/camcovers had been vented to atmosphere as opposed to through the pcv valves/inlet system the problem would not have arisen surely..........

Why get rid of them??

Dont catchtanks ultimately vent to atmosphere anyway?, and if boost pressure is getting into the crankcase to raise crankcase pressure you've got problems anyway.

 

I had a sticking pcv valve when I first got the zed and the crankcase was pressurising on boost.if the crankcase/camcovers had been vented to atmosphere as opposed to through the pcv valves/inlet system the problem would not have arisen surely..........

 

If you use a recirculating catch tank like the one in that Scooby thread that Zedwizz posted then the oil contamination is being removed from the blow by gas into the catch tank, but you are still putting hot gas back into the system. We want any air going into the engine as cold as possible. If you use a catch tank with a vent like Silverbullet used, the oil is seperated in the tank then the hot air vents to the atmosphere.

 

All cars have gasses blowby the piston rings to some degree without exception, it doesn't mean you have problems unless your rings are shot and so much is getting past that your oil pressure goes really high, and you find your dipstick being pushed out out of its tube. Piston rings have gaps so a tiny amount of combustion gas will leak past into the crankcase every time a cylinder fires. If you run high boost the amount of blowby will be greater. If you just put a filter on the end of the hose on a car thats running high boost it will soon become saturated with oil. The catch tank seperates the oil from the blow by gases and then vents it or recirculates it depending on the system you opt for. Or you could just drop the pipe down the side of the engine or under the car out the back to stop fumes.

If you delete the PCV valves,remember the oil will need more frequent changes due to contamination. What is often forgotten is that clean air is pulled into the crancase as well as expelling the combustion gases.

I personally,would keep the valves and re-route the vent pipes from the top of the cam covers.The main issue is oil not draining back on full chat coupled with hard cornering allows oil into the pcv hoses/valves and ultimately, the intake.