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I was wondering about this the other day.
I had purchased a nice catch can set up for installation on the Volvo to help with the turbo blow by, but never got around to it before we sold the wagon off into the abyss.
Certainly, I have ample oil left in the intake from the stock breather system on the S3. Even with extra baffle in the filler neck, etc.
I remember the Sharkvent system (not sure if that kit is still in production or not).
This would not have the capability to drain back into the sump like the DR version, but I'm in there enough to empty a can on a regular basis.
I was wondering about this the other day.
I had purchased a nice catch can set up for installation on the Volvo to help with the turbo blow by, but never got around to it before we sold the wagon off into the abyss.
Certainly, I have ample oil left in the intake from the stock breather system on the S3. Even with extra baffle in the filler neck, etc.
I remember the Sharkvent system (not sure if that kit is still in production or not).
This would not have the capability to drain back into the sump like the DR version, but I'm in there enough to empty a can on a regular basis.
What say the collective?
Oil in the S3 intake system is a big problem. Those side plenums always have many cc's of oil that pours out if them, when they are removed.
And like the S4 variant, oil in the intake system lowers the effective octane rating of the fuel and is responsible for a large amount of the carbon deposits on the pistons.
I just got done engineering and fabricating a complete ventilation system for the S3 variant, to keep oil out of the intake system.
The S3 proved to be an interesting challenge, because of the lack of room for additional pieces.
The prototype parts are on an large displacement engine, for testing.
Thanks guys for the feedback.
This is encouraging to know I'm not completely crazy yet.
I Bet the GB system will be bulletproof, like all his other designs.
I will try and fabricate something in the meantime.
In regards to the actual plumbing, somebody feel free to critique the rough sketch below and give me some feedback on the modifications please.
I can't remember which line off the filler neck has the check valve in it, lol.
And like the S4 variant, oil in the intake system lowers the effective octane rating of the fuel and is responsible for a large amount of the carbon deposits on the pistons.
I have been saying this for years. Not to mention lost horsepower from the lowered octane.
I wonder what the power increase would be for a GTS, where all you do is drill out the oil drain holes in the pistons and shark tune. There really isn't a way to tell how much the octane is lowered but I'm betting it is a lot.
...
In regards to the actual plumbing, somebody feel free to critique the rough sketch below and give me some feedback on the modifications please.
I can't remember which line off the filler neck has the check valve in it, lol.
I don't have much input on exactly how to plumb the vapor capture on an S3 - however I do suggest you close the loop - if you have good air/oil separation (you may need more than a catch can) then you should ingest the cleaned air back into the intake. It may have no appreciable oil - but is is not really clean enough to go to atmosphere IMO.
In my GTS oil separation system the whole thing is closed back into the CAI - it is about the easiest part of the system to implement.
Just buy a Mann Hummel Provent and do the plumbing yourself.
Alan
Way too much oil for the Mann filter to deal with, in these engines. Additionally, the engine compartments are so cramped on the S3 variant that there is not any place to mount the Provent filter.
Once the Provent filter gets saturated with oil, it no longer will flow enough air and the crankcase pressure goes up, again.
Ran into this problem with some GTS engines that had rings that were too gunked up, which forced too much oil to the Provent, overwhelming it. I found that multiple filter changes were sometimes required on these GTS engines to "get" the rings to seal/reseal.
Found out that it is sometimes tough to cure a bad design and years of poorly sealed rings, instantly.
For the S3 application, I had to engineer a different approach.
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!
Thanks guys for the feedback.
This is encouraging to know I'm not completely crazy yet.
I Bet the GB system will be bulletproof, like all his other designs.
I will try and fabricate something in the meantime.
In regards to the actual plumbing, somebody feel free to critique the rough sketch below and give me some feedback on the modifications please.
I can't remember which line off the filler neck has the check valve in it, lol.
Give the planet a break...please don't do it this way.
Venting any crankcase to atmosphere has been illegal since 1957.....for a very good reason.....very bad stuff for the environment.
Way too much oil for the Mann filter to deal with, in these engines. Additionally, the engine compartments are so cramped on the S3 variant that there is not any place to mount the Provent filter.
Once the Provent filter gets saturated with oil, it no longer will flow enough air and the crankcase pressure goes up, again.
Ran into this problem with some GTS engines that had rings that were too gunked up, which forced too much oil to the Provent, overwhelming it. I found that multiple filter changes were sometimes required on these GTS engines to "get" the rings to seal/reseal.
Found out that it is sometimes tough to cure a bad design and years of poorly sealed rings, instantly.
For the S3 application, I had to engineer a different approach.
The Provents do come in various sizes... While size & space in the engine compartments are certainly an issue there is still lots of space in the front fenders. I do use a Provent 200 on my GTS - it has a vacuum pump and another centrifugal separator in front of it stripping out most of the oil. But certainly doesn't get overwhelmed in that configuration.
How does an S3 compare to a GTS for oil ingestion - worse?
Anyway you are right - its not so easy to fix what Porsche never really did get (even close to) right on the PCV system.
The Provents do come in various sizes... While size & space in the engine compartments are certainly an issue there is still lots of space in the front fenders. I do use a Provent 200 on my GTS - it has a vacuum pump and another centrifugal separator in front of it stripping out most of the oil. But certainly doesn't get overwhelmed in that configuration.
How does an S3 compare to a GTS for oil ingestion - worse?
Anyway you are right - its not so easy to fix what Porsche never really did get (even close to) right on the PCV system.
Alan
S3 engines do not use the copious amounts of oil a 100,000 mile GTS uses....they have oil return holes in the pistons, unlike the GTS engines.
They also hAve two plenums with horizontal air flow and internal velocity stacks that act like oil separators. The plenums get filled with oil, but not as much oil reaches the cylinders, because of this design.
S3 engines do not use the copious amounts of oil a 100,000 mile GTS uses....they have oil return holes in the pistons, unlike the GTS engines.
They also hAve two plenums with horizontal air flow and internal velocity stacks that act like oil separators. The plenums get filled with oil, but not as much oil reaches the cylinders, because of this design.
Greg thanks - given that the plenums act as separators - would it be possible to simply add underside drain ports from the plenums to collect the oil in a (lower) catch can that could be manually drained from time to time?
Probably would mean welding on a drain port flush with the interior bottom of the plenums each side - maybe at the lower front end so you can drain as you brake?
Ok gentleman, before I jump in on this, let me ask a question to the forum. I don't really have an engineering degree to tarnish here, so let me put this out there for discussion:
How much vacuum do I need to effectively pull oil vapor thru a catch can?
The stock system, I assume, puts the oil vapor into the throttle body in order to combust it but also to pull it thru the breather system under vacuum right?
If I eliminate the communication from block to the throttle body, and run lines from cam cover into one line and run that thru an in-line catch can -- with the destination of that line into the oil filler neck base... Does that accomplish what I effectively want, in a closed system, without overwhelming the can right away?
In the stock system, the filler neck gets oil vapor from the front half of the block and also from what ever gets past the baffles right?
It essentially has two vacuum points (one at base of neck and one on neck). I don't know how much breathing is needed there either, but I could leave the smaller line in tact, that hits the filler cap area.
08-19-2017, 07:20 PM
Is there any advantage to a catch can?
