FredR

Tuomo,

I will try to answer your querie best i can:
1. The check valve is one of the pro vent valves- I carried out an empirical test to see how much resistance it put up to flow before I installed it and it seemed negligible- I specifically mounted it in the horizontal plane to minimise the resistance to flow [you cannot mount these things vertically flow downwards or they do not work as a check valve unless there is a hurricane blowing].
2.Whereas I am confident it will prevent a back flow into the inlet tract I really do not know if it permits fresh air flow- I am working on the presumption that if the stock system permits this to happen it will still do so under some conditions such as engine braking- that or the pro vent will allow reverse flow to suck some fresh air in.
3. Originally I ran a 1 inch hose from the pro vent outlet to the underside of the car exiting in the area by the side of the undertray in the hope this might help educt a slight vacuum from the air stream rushing by. when I inspected this hose there was no sign of any oily residue in the pipe so at the moment I have simply allowed the gas to come out of the exit port directly and I am looking for signs of oily residue- non to date. when i have tested the current set up to what it does [or does not do] I intend to mount a fitting into my alloy under tray- a copper elbow maybe- to see if that will work as an eductor. i have temporarily fitted one of those simple filters on the outlet in case of air being sucked back in
4. My motor is stock and it is the 200 series design. I want to detemrine why this motor has high oil consumption when there are no obvious mechanical signs of why. of course it could be ring wear but frankly I do not want to disturb the bottom end of the motor unless and until it is absolutely necessary.
5. As to the direction of flow through the tee I have no clue at the moment. I suspect it may well be a mixture of both.
6 I collect the oily oulet in a tape sealed catch bottle to test for oil separation in the pro vent. with the filler neck vent only it caught virtually no oil. This suggests that the baffle is very effective at separating the oil but it also made me wonder if the baffle was too restrictive for venting. Thus I am now venting the cam covers as well so that hopefully the crank case will be in equilibrium with the cam covers. i have also read the theories about localised pressure in the crankcase so this makes me wonder whether the rear section of the cam covers should also be vented in this arrangement.

Bottom line - if i can hit on something that improves the situation it will give a clue as to what to work on. With the GTS system fitted i found that during Sharktuning that i was having to pull the timing at top end. However, having read ken's exploits on mapping the S4, he initally reported things I found at 5k rpm upwards. Now I have worked the breathe system i intend to revisit the ST2 to see if there are any noticeable differences to the tuning possibilities.

All I can say at the moment is that the old assometer tells me the motor is running better than ever. I have also tried some STP in the oil. after filling my cam belt tensioner with the stuff most of the bottle as left over and after reading it had good zinc content I thought why not give it a go in the motor given it is rather hot here during summer time.

Thus I am trying to have a go at implementing what I have read here or variations thereof. Nothing lost unless of course I somehow wreck the motor. I would like to bolt on some more power but have on intention of doing so unless I can attenuate the oil consumption- be it by luck or judgement.

I have ordered a borescope to take a look down my cylinders to see if there are in clues there. It is a bit like a detective story really- not quite sure whether I am a Sherlock Holmes or an inspector Clouseau- probably the latter!

Regards

Fred

andy-gts

Is there a summation of the system you built for the crankcase ventilation or should I just read the whole thread?

thanks for the write up

ptuomov

Andy --

Was this question addressed to me?

In case it was, I have a Keep-It-Simple-Stupid system on the car now. That system works and the car doesn't puke oil on the dyno when held under load. However, I don't believe it is the optimal system.

I don't yet know what the optimal system is. We are in the process of installing many pressure sensors on the car and have ordered many more sensors that we'll install when they arrive. After we get the data, we'll try to come up with an informed opinion about what is happening inside the engine per load and per rpm. We'll then design the "final" system based on that informed opinion.

Best, Tuomo

ptuomov

Did it look like this:



Yes, I can't think of a function for that chamber. Maybe it's there just to make the plastic part stiffer and less likely to leak.

It was a separate system that appeared to require the minimum amount of head scratching to get integrated. We'll see if that appearance translates to reality. I think someone might be able to buy a regular flow sensor and save some dollars with some effort.

Alan

Yes thats it - brings back memories now - since I filed all that away with a power file - easy to do but very messy...

On a GTS there are no ports in that end section - so both baffled ends are completely pointless.

Alan

ptuomov

Last call for ideas on how to do a boosted engine crankcase ventilation system the best way. All ideas are welcome, we'll have to lock down the next iteration to test soon. The floor is yours, ladies and gentlemen.

Alan

I stand by all evacuation out of the crank vent via a good crank baffle separator like Greg's or even better - a high flow version built into a new tall stack replacing the whole oil filler neck. I can imagine how to do nice tall baffled drain back separator here. Then create a new oil filler direct into the pan like the older models had.

Evacuate from the crank separator via a vacuum pump so you always have evacuation flow - then clean that through a high volume separator (maybe a big Provent or Colin's separator) then recirculate the oil drains to the heads and vent the cleaned flow back into the atmospheric intake to the supercharger/turbocharger.

I'd allow some atmospheric air flow into the heads (one way vacuum limiting valves) under some conditions (low blowby flow cases) for clean air flushing.

I've been running like this for over 18 months now - everything works well. I don't have forced induction but if I did I wouldn't have to change anything in how this is plumbed.

I think it's even more ideal for forced induction because it takes all reliance on intake vacuum out of the equation and yet keeps a fully closed system that actually does positive crankcase ventilation all the time (where positive means 'assured' not pressure).

Alan

ptuomov

This is an interesting arrangement. Some questions about it:

What's the force that pushes the oil into the valve covers? What's the pressure inside the ProVent and what's the pressure inside the valve cover to which the oil is supposed to drain? Is the pressure differential enough?

The ProVent has two valves, one safety valve which we can ignore, and the second more relevant valve in the outlet port that controls the crankcase pressure. Is that going to leave enough pressure inside the ProVent to push the oil up enough?

Suppose there's enough pressure differential between the ProVent and the valve cover such that the oil flows up to the valve covers. If oil drain hose flows dry, what now prevents the crankcase gas from the pump outlet from flowing up the dry oil drain line back into the valve covers, reducing or eliminating the crankcase vacuum? Is it just the restriction caused by the small inside diameter of the oil drain line that keeps any vacuum in the crankcase? Or is it that the pressure limiting valve in the ProVent outlet going to keep the pressure inside the ProVent just right relative to the valve covers such that oil flows up but not too much gas will flow up in addition to the oil?

Why drain the oil to heads in the first place? Isn't oil ideally drained in systems like this into the sump and preferably under the oil line in the sump?

Not saying what you have doesn't work. It seems to work based on your experience. I am just trying to understand why and how it works.

Alan

Well my set-up isn't exactly like I described - but Colin's pretty much is like that. I described that version because mine is over complex if starting from scratch.

The provent valves are as you suggested 2 versions - the one in the cap is a simple over pressure atmospheric relief. If restriction through the provent (for whatever reason) is creating excessive positive crank pressure it will open. The other is designed to limit crankcase vacuum in a closed system. It is an output valve and is dependent on vacuum at the provent output (e.g. typically from the intake) to limit flow. In an open system it has no effect. In my system with pumped flow on the input to the Provent it has no effect since there is no vacuum on the output, so it acts like an open system though it is not. The provent output feeds to the atmospheric input (e.g. just post-filter to the forced induction pump), or in my case pre-filter to the airbox.

Now in my actual system I have two series separators (or even 3) which is in need of simplification I think.

The first separator fed by the vacuum pump is a small high velocity centrifugal with 2 flow reversals - 1 true oil drain port and a secondary relief port. These 2 ports are connected back one to each head (front ports). The main oil drain connects via a mini-separator (#3) (clear body) mainly to monitor recirculation flows - it is not functionally required. Each of these ports has a restrictor - since they are what limits the recirculation flow and therefore indirectly the nominal crank vacuum level. Flow from both these recirculation ports is mostly gas/vapor with only occasional liquid oil separated out.

The output of this primary separator feeds to the provent input. The Provent oil drain does indeed still drain to the sump via a check valve (and to below oil level). Like I said its too complicated to suggest as a baseline system - but it works as I described in the simpler system. Most of the vacuum pump flow is recirculation flow (to the heads) - basically the Provent now only sees net blowby flow. The recirculation path through the first separator strips most of the oil that is in the evacuated vapor flow so it goes back to the heads without loading the Provent filter.

All flow is now down the head oil drain ports driven by the crank vacuum, oil pump and recirculation flows. The only thing driving the heads to a higher static pressure than the crank are head oil flow, vacuum pumped re-circulation flow (nets out) and valve guide leakage blow by. This down flow is sometimes augmented by fresh air flushing from the VLV's at the rear head ports - but only when vacuum level is high enough to drive that (which typically means blowby is relatively low at mid+ RPMs)

The only way I see the re-circulation ports at the head reversing direction is if the vacuum pump fails and blocks main crank vent flow. There would be no reason you couldn't add low crack pressure check valves in the recirculation lines but I see no need.

Now because I am paranoid - I do have a check valve around the vacuum pump - if it should fail - positive crank pressure can bypass the pump and flow through the usual separator path - (it's about a 2 psi crack).

The crank typically runs between 4" Hg and 8" Hg max most of the time. I have measured vacuum at the front head 'breather' ports and at the crank (at the the filler neck) and there isn't an appreciable difference under normal driving conditions. Not sure what the conversion factor is for "HG vs "Oil, but it is a significant factor - "H2O is about 13.6x "Hg so even if the oil factor was half that - plenty of lift. The body of the first separator may be pressurized slightly due to the restriction of the plumbing/ body and Provent filter - it which case the total delta is higher. I haven't measured it - I have no easy means.

Alan

andy-gts

Hey Alan,

can you post a photo of how this is plumbed...?

Alan

Well its a bit hard to photograph - if you have played with this kind of thing you realize space evaporates fast. I'll post a few for ideas more later - you have to imagine some of the connections that are buried deep!

Alan

andy-gts

is there a transucer you can drop in the dip stick hole to check crank case pressure and plot it against rpm later?

ptuomov

The problem with designing these kinds of systems is that they get real complex real fast when one considers all operating modes. Before soon, one looks back at the plan or the engine bay and has to say...

Alan

Yes indeed ...

Guide:
----------------------------
1 12AN 'T' from the Oil Filler Neck bottom (Greg Brown baffle under the filler neck)
2 The safety check valve (2 psi crack) path around the vacuum pump in case the pump ever fails (belt etc)
- To the right of 2 the black thing is the new oil filler port - direct to the oil pan in the OB location.
3 Feed to the vacuum pump intake (located in place of the air pump) - config BTW passes emissions just fine 2x now
4 Feed from the vacuum pump to the 1st AOS main input
5 1st AOS 1st (high velocity centrifugal) - installed inside air pump filter housing under the lid
6 Feed from the output of the 1st AOS to the input of the 2nd AOS (Provent 200)
7 Provent 200
8 Output from the Provent 200 (Seems to be as clean as a whistle - no oil residue on the tube insides)
9 Connection into the CAI ahead of the filter at the air pump port location (elbow installed instead - bigger)
10 The output of the safety check valve - not normally flowing anything
11 Same as 10 above (this line does a U bend at the fan shroud so the plumbing can fit & flex) feeds secondary input path to 1st AOS
12 Oil drain output of the 1st AOS
13 Mini 3rd AOS - for evaluation purposes only - to monitor the oil recirculation flow (not functionally needed)
14 Oil/vapor recirculation feed to the passenger side head front breather via a restricted orifice (drilled bung installed in the hose)
15 Vapor(/Oil) recirculation feed to the driver side head front breather via a restricted orifice (drilled bung installed in the hose)
16 Cap over the breather connection on the OFN
17 This intake connection is sealed (no flow) bunged in the hose
18 Vacuum Limiting (one way) Valve (~8 "Hg crack) installed inside the airbox bottom passenger end - feeds filtered air into rear passenger head breather port
19 Vacuum Limiting (one way) Valve (~8 "Hg crack) installed inside the airbox bottom driver end - feeds filtered air into rear driver head breather port
20 New Oil Filler cap - direct to sump/pan

So I have all 4 cam 'breather' ports installed (all elbows without restrictors) - however all 4 flow inward to the cam covers only.

The 1st AOS doesn't clean well enough on its own and the 2nd AOS (Provent) doesn't flow enough on its own to handle the maximum recirculation flow (or at least it sees so much oil stand alone that the element gets overly restrictive over a quite short time). So in this configuration the first separator is in a re-circulation loop and strips quite a bit of oil but doesn't result in a fully clean output, then the net out-flow portion of this goes through the Provent-200 to clean up the remainder via further centrifugal and coalescing element cleaning.

Alan

Alan

You can quite easily attach a vacuum gauge to the head breather ports or the OFN ports - as to data logging it automatically - you need the same sensor and a PC acquisition method. Do-able.

More interesting still is logging the actual blow-by volume at the same time with some kind of flow meter (Tuomo has one)

The dipstick tube is harder to attach to reliably. The other issue there for normal running is making sure the dipstick (and tube to pan) actually seals well.

Alan