s2konroids

So I've had this catch can set-up for a while it does work accumulating mainly water but it does have oil in it (90water/10 oil %), on the airfield day at north wealds it was commented that occasionally my car would burn oil after idling and setting off, other times it would be fine. I did see some others cars expel a bit whilst waiting behind them.

My car has done mega mileage so i wouldn't be surprised if some is escaping past the rings, or i was thinking is my catch can adding to the problem?

Here is my current setup...



Pretty self explanatory but main bits are circled in yellow circles, i acquired a hollow elbow from a scrap yard to replace the stock PCV (one way valve) as it can no longer as easily flow through. My thinking is during vacuum the PCV valve opens at a particular pressures and thus vapour/oil gets sucked back into the intake manifold, but it surely must get pushed out too and actually escape now - it appears so due to the collection in the CC.

I've capped off the intake manifold too (due to the above point) and capped off the pipe into that goes from the intake tract to the front breather port - again as the you are accelerating hard it will suck out the oil/vapour from front port.

You may ask why go to all this trouble, firstly to stop shitting up the insides of the throttle body, map sensor and intake manifold etc and to reduce chances of knock by removing oil content from ingested air which is theory would allow you to run more ignition timing thus slightly more power. Boosted S's seem to suffer from blowby. Lastly there are brillo pads inside to add a a kind of baffling. On the stock setup its setup to be emissions friendly as the vapour etc is draw back into the engine to be burnt up but has the problems mentioned above.

My question is do you think my current setup is not extracting all of the vapour/oil and sometimes it accumulates in the cam case?

Oh and i know this isn't technically emissions friendly .

Cheers

GavB

Just in my opinion, although what you have done is a good installation, it doesn't seem logical to me.

The main reason for the PCV and line to the intake is too draw vapour from the crank case by pulling in fresh air through the front breather - essentally ventilation. A secondary function of the front breather is to make sure the crank is always open and cannot overpressure.

I think you are correct that the main loss of oil will also be through the PCV when it gets trapped up there and then sucked out with the air. The water you are seeing is just condensation, and would not exist as condensate if it wasn't for the catch can anyway.

So what about the oil. Stopping the oil was your main driver for this, and thats why I don't think what you have done is logical.
Doing away with the PCV system was the main decision here, and you have chosen to do that accepting whatever downsides are there are to that. But having done that you've not realised the gain - without the route to the manifold, you should have just blanked off the port on the engine altogther. That would mean no oil could escape at all. There is no need to leave it with a path to atmosphere IMO, thats what the other breather port is for.

The catch can is designed to "knock out" the liquid in a liquid/vapour mix, so that the vapour can continue to its intended destination, as you have deleted the destination the catch can is pointless for the PCV port.

If I were to install a catch can it would be between the PCV and the intake when maintaining the PCV line to the manifold.

As for the Breather pipe I would not bother with the catch can on there - my hose and point of connection to the inlet are completely clean.

In short. Cap of the PCV alltogether and remove the catch can. route the breather pipe as usual or install a local mini filter. Give it a try!

ps, sorry for being condesending...

s2konroids

Thanks Gav , I've spoken to my mate regarding this setup and we tested it the other day - a few changes are needed, it is working though.

When boosted like we both are the main issue is to make sure it's not over pressured you can test this by measuring it from the dip stick hole or using a balloon. I don't know if you have a stronger one way valve but it's a must as it will not allow boost in the crank case, as it will possibly bypass the stock pcv valve as it was never designed to handle boost, however I recall later pcv's being stronger. It would go inline back to the intake manifold from the pcv. I don't need one as the link has been removed.

The front port does breathe in and out which is why it's the biggest out of the two ports, obviously it breathes out and the suction of the intake sucks up vapour etc ready to be burnt in the engine, stock configuration is not good for power/maintaining cleanliness of the TB/map sensor etc. The rear port breathes out and is sufficient to push the vapor out without the aid of a pcv and intake manifold suction. It's worth noting though I have an earlier engine than you with many more miles .

My setup is how he has rigged up every other car when boosted running a catch can. The problem is though my pipes are a little too small diameter wise, also the filter is too small so it needs to be bigger to let out pressure and breathe efficiently but also my brillo pads inside are too compact - one of the ports inside was gummed up. These contributing factors make it less efficient. The stock system is purely setup to be emissions friendly.

IIWU id definitely look at the boost in crank case issue installing a strong one way valve.

It's bugged me for a while this setup.

GavB

Thanks will definitely have a look at my pcv, see what back pressure it can hold.

Does your friend offer any explaination as to why the pcv valve location can't be blanked and has to go to the catch can. Just because he's always done it doesn't mean he got it right first time!

Without the manifold vacuum there is nothing promoting a flow in one direction, so I don't think you can differatiate any more any say one breathes in and out and one only out. They are now just holes and will both do the same, mainly venting blow by pressure. The front hole is adequately sized for this, so still don't see the need for two vents.

s2konroids

Sure the pcv can be capped off but where is the blowby going to go?

PCV's don't function under boost, again it flows out of the rear port.

GavB

Won't it just blow out the front breather hole, same as with a n/a engine on WOT? It's all the same circuit.

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Without the manifold connection why would it flow out of the rear port more than the breather port, especially as its a smaller diameter?

Btw am happy to be disproved, as I am only surmising.

s2konroids

I'm enjoying the craic, IMO when boosted the S is more susceptible to blowby.

It blows out of both ports by design - try putting your finger on both ports it will blow out of both. In stock configuration is will blow more out of the front one and due to being connected to the intake, its debatable how much more it blows, they are a separate circuit probably configured to stop oil splash - however one would need to open the engine up to see exactly what happens.

Yes, when blocked off it would flow through the front but this isn't sufficient hence retaining both ports.

N/A as you say uses vacuum to pull out any unwanted crankcase pressure but since we are supercharged, that doesn't work quite the same as N/A.

Hence why you route both on the cam case to the same catch can that will remove the oil from the air and vent the extra pressure (via the installed breather) - you do not want a sealed system.

Bear in mind this is more important for us being supercharged.

Its easy to test these things both adding and removing the CC and monitoring the pressure being expelled from the dipstick hole.

With all the above said, I'm hoping why you see its more logically to hook it up this way.



If you want to coat the inside of IC, TB, IM, slightly cake up the MAP sensor, reduce the ability to run as much timing advance as possible without knock and 'possibly' introduce boost into the crank case (if the mk2 PCV is weak like AP1) then leave the stock configuration as it is to save some penguins .