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I think the main thing about your system that I would change is to have the manifold vacuum to pull air from the rear valve over ports and have the MAF elbow pull air (ultimately) from the front of the engine. This is because during the car acceleration and no manifold vacuum the oil sloshes to rear of the engine and during car deceleration and high manifold vacuum the oil sloshes to the front of the engine.
My current setup as shown above after 2-hours of blasting around on the back roads, I had maybe a dime-sized splotch of oil in the bottom of the ProVent.
Prior that, I was going to to plumb a line with a one-way valve into the oil pan, but with those results, I am not going to bother for now. So for the time being I'll keep it simple as is, continue to evaluate, and keep your suggestions in mind if need be.
I do have the I-J scraper on this engine, and maybe the reason why so little oil found its way into the bottom of the ProVent.
I did have to mod the ProVent by sealing-shut the valve on the side. Prior to doing-so, at idle I heard an intermittent tap-tap-tap-tap sound, and it was that valve opening/closing and letting un-metered air in because of the vacuum created in the crankcase. That is when I got the idea to get/use metered air from the MAF elbow to properly complete the circuit. Plus, it provides good circulation with the air moving/flowing back to front.
Bonjour,
And thank you for your feedback. Sorry for responding so late... I did not get any alert in my mailbox...
It is so hard to understand how it works... So all advises are appreciated...
Your set up have some similitude... and looks both quite simple...
I will think about them and let you know what I will try!
thank you so much.
Raphael
Bonjour,
I had my mind focused on my gearbox and TT rebuild so I let the intake system idea on the side these last month... But now, I'm back on that!!!!
I spent a lot of time reviewing the 2 set up proposed. Thank you again. And I have some questions for you. I put your set up in the following picture with some modifications (in green). I don't know if they are good idea or not:
Swaybar,
1- As you iterate on your set up, did you tried with what I'm proposing? In case of important blow by I would be more confident with a second straight way for the pressure to go to the intake/TB...
2 - I do not understand how you conclude that no oil could go to 4. Sorry if my level in English is not good enough. On my car, I found oil in the hose that goes from the passenger rear cam cover port... don't know if it come from the cam cover or from the hose that goes to the one way valve on the stock set up...
Your set up looks to me a nice simplification and improvement of the stock set up.
Ptuomov,
1 - Same question as for Swaybar. Even if you keep the 2mm restrictor as on the stock system, I would be more confident if more pressure from the crankcase could go to the TB/intake,
2 - Should be obvious but as I have no experience on this kind of system, is the incorporation of a provent, as I proposed on your set up, a good idea?
Your set up is the exact opposite of the stock set up and in the same time it work with the same "spirit", except the blow by back up pressure release line.
Both of you removed the Y fitting in the intake elbow and I think also that this staff is not reliable. Last time I removed my intake I had to change it because it was distorted and each time I had issue to remove leak in that area. I think I have a small leak in the intake because I have a high RPM at idle, and I'm pretty sure it is in this area... I'm preparing my plan for the day I will, one more time, remove the intake... And your feedback are great help for me.
Raphaël
Bonjour,
After receiving a provent, I'm realizing that there is a valve in it and there is no more risk to have an over pressure in the crankcase, as long as the hose that goes from the provent to the filling neck is well installed. So the additional hose I proposed on both previous installations is nor necessary...
Have all a great weekend,
Raphaël
Bonjour,
I had a leak on my intake so I removed it and I take advantage of this to change my breather set up
Ptuomov, I finally choose your set up with a Provent. I was worry about the 1" hose but finally it fit from the TB boot to the Provent. From the filler neck to the Provent I used the GTS port I created and I created an additional one underneath the cap in order to as much air as possible. Here is the scheme :
I intent to use an additional small catch can for the pick up from the rear cam covers elbows hose but I have to find a way to install it. I will do that latter, if required...
So far the car is running good. She looks to enjoy the set up at high RPM (over 5000 RPM the car have more HP). So far, but I did not drive that much, not a drop of oil in the Provent...
Looking forward to try this on track!
Merci,
Raphaël
Bonjour,
I did not drive a lot yet but so far I did some runs at high RPM :
- not a drop of oil in the Provent,
- but I found oil in the small hose after the restrictor...
I'm surprised of that... residual oil or the TB is sucking oil from the hose in the back between the rear cam covers?
I will try to find out this week end.
Raphaël
Bonjour,
As I would like to have a better idea of oil in the small hose C/D after the restrictor I finally installed the additional catch can. Here is my set up :
After a 250km (about 150 miles) trip of normal drive with some great accelerations, I get about 10mm (about 0,4") of oil in the cup of the catch can :
And I have almost nothing in the Provent. I have a model with a metallic mesh. I found trace of oil in the Provent, below the oring the filter. Maybe I have to use a Provent with a cotton filter instead of this metallic one?
I'm surprised about this result. I imagined that I would have found more oil inside the provent and almost nothing in the catch can...
Maybe air charged of oil is moving between the 2 rear elbows under acceleration and then because of that some oil is laying in the hose. So at idle or when I lift the foot, the restrictor is sucking oil laying in the hose?
Or maybe the restrictor is sucking anytime?
It is not that much oil and I don't know if the model of catch can I used is efficient or not. I just bought something cheap to have an idea. If someone know something light and small working better, I will greatly appreciate to get the information.
Anyway, on track it could only be worst... I have a track day planned early July, I will see then how much oil could be sucked from there.
Bonjour,
As I would like to have a better idea of oil in the small hose C/D after the restrictor I finally installed the additional catch can. Here is my set up :
After a 250km (about 150 miles) trip of normal drive with some great accelerations, I get about 10mm (about 0,4") of oil in the cup of the catch can :
And I have almost nothing in the Provent. I have a model with a metallic mesh. I found trace of oil in the Provent, below the oring the filter. Maybe I have to use a Provent with a cotton filter instead of this metallic one?
I'm surprised about this result. I imagined that I would have found more oil inside the provent and almost nothing in the catch can...
Maybe air charged of oil is moving between the 2 rear elbows under acceleration and then because of that some oil is laying in the hose. So at idle or when I lift the foot, the restrictor is sucking oil laying in the hose?
Or maybe the restrictor is sucking anytime?
It is not that much oil and I don't know if the model of catch can I used is efficient or not. I just bought something cheap to have an idea. If someone know something light and small working better, I will greatly appreciate to get the information.
Anyway, on track it could only be worst... I have a track day planned early July, I will see then how much oil could be sucked from there.
Have all a great day,
Raphaël
The plumbing discussion, in this thread, got so absurd that I quit reading this, months ago.
This current plumbing diagram makes absolutely zero sense.
You've completely eliminated the functionality of my valve cover oil separators with this current method of plumbing.
Hooking valve cover to valve cover does not allow any separation of the oil, nor does it allow the valve covers to vent, which is needed for the oil to return from the heads to the crankcase.
Your current plumbing diagram is a disaster.
At sustained high rpms, the heads will fill with oil, which can not drain to the crankcase, because of the vacuum on the rear crossover hose (from the intake system, via the catch can.)
This oil will rise in the heads and be sucked into the catch can.. The catch can will be overwhelmed and oil will be sucked into the intake.
Semi-retired, as of Feb 1, 2023.
The days of free technical advice are over.
Free consultations will no longer be available.
Will still be in the shop, isolated and exclusively working on project cars, developmental work and products, engines and transmissions.
Have fun with your 928's people!
Raphael, the first thing I noticed about your setup is that you are pulling in un-metered air from your air filter into the driver's valve cover, which eventually ends up in the combustion chambers, so your mixture will be leaner than what your MAF reported to the computer.
I shook my head at this, months ago....but just decided that it wasn't worth my time to ask this question:
But now that this thread is back up, I'd sure like for you to explain how air from the vent to the driver's valve cover can be drawn into the combustion chamber, as unmeteredair....affecting the mixture....
Specifically, where is the connection from the vent in the driver's valve cover to the metered air, past the MAF?
Thank you Greg for your feedback.
On what I observed what you explain make sense... oil is moving through the the rear hose and is sucked into the intake. That’s clear. The catch can is already over melted as I found oil between it and the intake...
what I understand is that this option will end up with always more oil sucked from here...
Raphaël
Some points:
The goal should not to have an oil free Provent. It is the air/oil separator. If it is oil free, it isn't doing anything.
For extended high rpm use (track use), the primary goal is to help the oil return from the heads to the crankcase, in order to keep the engine from running out of oil at the pick-up.
Oil in the intake is a secondary concern.
For oil to more freely return to the crankcase from the heads, any form of vacuum in the heads is a bad thing....unless the heads are completely dry sumped.
For oil to flow freely return to the crankcase from the heads, pressure in the crankcase is a bad thing.
Once the oil return to the crankcase is improved, separating oil from air and keeping oil out of the intake is the next priority.
The biggest volume to utilize for air/oil separation (far bigger than the Provent) is in the cylinder heads. My valve cover oil separators are made to help with this and work extremely well....if allowed to function.
Hooking the breathers in the heads together is generally counter productive, unless you are moving air from a high pressure area to a low pressure area. Without air flow, oil separation does not take place.
If one feels the need to try and improve what I've already done, proven, and sell, start with a clean drawing. Mark the various vents, elbows, oil returns, other access points with what they currently have....pressure, vacuum, stagnate air, oil flow, oil not flowing, etc. From there, figure out how to improve the system...get the oil to return to the crankcase better and keep as much oil out of the intake as possible.
There's limited ways to accomplish the above, with the pieces we are given, on a stock engine. And without dry sumping the heads (the best solution) or adding a vacuum pump to the crankcase, you will end up with something that looks like what I do...
Bonjour,
I have a track day soon so I need to go to a secure configuration. It will be great if I could avoid another intake removal. As I plugged the port with the valve on the filler neck, I will connect the intake like on the GTS but with the Provent and the catch can as they are already installed. That way I will be able to check what is sucked from the crankcase.
I hope it will be not worse than my initial set up...
Bonjour,
Not easy to route correctly a hose from the throttle body big rubber elbow to the filler neck... but it is done!
After a 100km ride and some high RPM accelerations, I found oil in the catch can but not in the provent. Maybe I have to sustain high RPM and high load to get oil in here.
But thinking about the S4 stock set up and what I did here, I think now it is not correct... I really do not understand the GTS set up..
With this hose that goes from the big rubber elbow to the filler neck, the air will go here and not that much through the passenger cam cover..
I think I have to put here a check valve to force the air to breath the passenger cam cover... and only go to the TB when blow by is significant.
And same thing in the other way... the S4 set up looks smarter with a load to open the check valve... so the air goes here only when pressure is too high...to help the big oil separator (passenger cam cover)...
Does someone has a source for a similar check valve than the one on the S4 filler neck?
Raphaël
Bonjour,
I found a valve and it is on the car. Now the catch can is catching about the same amount of oil than with the previous set up. But this time vacuum is in the filler neck. And atmospheric pressure on the rear cam cover elbows.
Raphaël
06-24-2020, 04:34 PM
