crank case ventilation

[Fixer]

I know you guys and gals all understand how important crankcase ventilation is, how it increases performance and so on.

Anyway i noticed while tinkering that the breather vent on my '83s oil fill lid was restricted way down to about 3/8",

the O.D. of the breather vent on the lid is a nominal 1". I bet many of you have already done this but thought i'd post anyway. Sorry i did not take a Before dremeling picture. The After pic is shown though. 3/8" to over 7/8" is considerable.

Anywho, it is very simple to dremel this thin restricter out of the beather tube.

Had my Daughter rev the motor before and after and it's a big ventilation gain.

I thought this may have been done to control excess oil from entering the intake and deleted the vent hose and capped the intake port.

I then ordered a filter/separator from Summit. Very nice product $23 plus shipment.

Venting to your intake is not great as the oil deposits can build up and lead to bad things like detonation and maybe pre ignition..

Seems this style oil filler is up to MY '86

[Danglerb]

Hope it works for you, but not something I would try.

[Alan in AZ]

So you are now fully emissions illegal!

I don't think this is a good idea at all. If you were ingesting oil before you will now be filling that little filter up until its laden (BTW its a filter in that configuration* regardless what they call it) - then splattering it all over the engine.

If you weren't ingesting oil before why bother polluting the environment for no reason...?

If you have a real ingestion issue you need a much more elaborate solution than that (Guess how I know about this stuff - 7 years and lots of money - many good ideas - most of them didn't really work though... finally happy with results). YMMV & early cars had far fewer serious ingestion issues.

*if this were mounted vertically as intended it could be considered to be a very basic separator... However it still might blow oil out depending on how much you were ingesting before since it has a very small area and no secondary catchment.

Alan

[Opelotus]

I do not like the way the stock system functions on the 16V cars and definitely think it is worthwhile engineering a better way to separate oil from crankcase vapors.

I had tried a setup similar to yours in the past and although it may have changed crankcase pressure, the car stunk to high heaven! I ended up putting it back to stock in short order; anytime I ran the heater in the cabin I came home smelling like oil and such.

Have you considered the Mann/Hummel ProVent? I hear it works pretty well and it can be configured to return separated oil to the pan.

EDIT: I should mention that the early cars ('78 or '79) had an oil cap sans the restrictor. It also has a longer "base" that extends farther into the oil separator screen. I have a picture comparing the two, will see if I can dig it out.

[Fixer]

Alan,

They have surrounded my garage! Please call the EPA off!!!

No ingestion problems now or ever, my motor is in fine condition and i'd like it to stay that way. The breather hose was dry (on the inside) when removed.
Brian who tracks the now broken 'Casper' vents the same way he tells me and has only noticed a 1/16" of oil in his K&N filter/separator after hard racing for the day. Road use i should be fine. And please note that i do not have a exhaust catalyst either. I drive this car very little. Still 65k miles, had 63K when i brought her home. If you are concerned about global air quality, China and India are much bigger offenders than my little 928.

My car is an Antique here in (cough, cough) Pennsylvania and exempt from emissions testing.

OPeletus,

Thanks for the useful info, my hood is vented and it works rather well.

I have not smelled anything as of yet and used the heater this am.

Breather has no oil in it on day 3.

[Pete R]

That way will just fill the filter element and drip all over the motor. The fill cap should be routed to a catch can. I have done this to all my turbo cars as the blow by is much more that a NA car. It if very effective and whole can set up can be bought for under $100

[Crumpler]

I say ...If a gain is noted, then thou shall continue thine good work.



Then go remove the restrictor on your shower head.

[Alan in AZ]

Sorry its silly - if you have no ingestion problems - save the environment.

You won't get any more power...without vacuum - that's really just an illusion.

The separator also isn't one unless its basically vertical - this almost certainly will drip on your engine, regardless how old it is or how little you drive it.

This is just not a smart move folks - just makes everything worse (and yes it will indeed stink).

Alan

[Pete R]

Oil vapor can cause loss of power and detonation. Chances are that's not happening with a NA car but it can happen. The most enviro friendly alternative I imagine would be a catch can that wouldn't burn the oil vapor at all. The oil also deteriorates the seals on the intake track.
Blemished Polished Aluminum Breather Tank Oil Catch Can Tube with 1 2" Ports | eBay

[Alan in AZ]

Originally Posted by Pete R

Oil vapor can cause loss of power and detonation. Chances are that's not happening with a NA car but it can happen.

If it WAS happening - it would be pretty obvious - you'd feel it (esp on high G corners) and hear the detonation. This is not conjecture - my car did this extensively and it was basically impossible to miss if you pay any attention to what's going on.

If you don't suffer power loss, detonation or excessive oil consumption (>1 Qt/1K miles) - leave everything alone.

I agree excess ingestion can be potentially damaging - but I'd highly doubt it happens on a correctly functioning 1983 car @65K - you'd normally need to have major bore or ring wear to provoke it on those cars - and you'd know it. At 65K if the engine is still good - why mess with it? - just drive it! (more)

Originally Posted by Opelotus

I do not like the way the stock system functions on the 16V cars and definitely think it is worthwhile engineering a better way to separate oil from crankcase vapors.

I agree that Porsche never really figured out a good crank ventilation scheme, but on early cars it really wasn't much of an issue anyway. In terms of engineering a better way - this CLEARLY isn't it.

Much later cars can have quite serious problems with this - because of relatively poorer breathers & separation, larger flow rates, higher RPM, longer stroke, worse crank/rod big ends. On those cars even quite elborate solutions including Provents and other improved baffling, hose rerouting, crank vent baffles, etc etc still really aren't fully effective. Just feel lucky that you don't really have a problem that needs any solving...

Alan

[Crumpler]

...and Matt, buy some hand cream while you are at it.

[Fixer]

Day 4,
took the RS to work and ran errands.
Did about 25 miles today. pretty warm day, had fun.
A long highway drive, lots of high revs.
Not any oil whatsoever in the separator.
Not a speck that i can detect. Very surprised
you guys almost had me convinced.
Did not notice any "stink" as i said
my hood is vented.

This video is titled Test crank ventilation for off road use
and was shot moments after pulling into the garage today.

Alan, i plan to take this car to New Jersey Motor Sports,
Just having fun experimenting.

This motor was really cared for by the original owner until 2012.
In my service receipts, he always changed the oil before 2000 miles,
once after only 700 while having a bulb replaced by his Mechanic.
He really kept up with this.

Hey Dave!! I know, my chances of a hand modeling career are slim..

YouTube

[Alan in AZ]

Glad you are happy - do what you will - its your car

However I really don't see the point if there was no issue to start with. Anyway you can always take it off quietly later in the summer when the smell and the oil mess start to bother you.

To everybody else - just don't do this.

Alan

[Fixer]

OK Alan,
Have a great weekend Buddy.

senza olio!!
Crank case vent test only,j for off road use - YouTube

[Danglerb]

Matt, just for S&G put a plastic sandwich bag over the filter and seal it closed with a rubber band or a zip tie, then do the test again to see which way the air flow is.

[Fixer]

Mike,

The air flow exits the breather as it should and with normal force.

once i get my no start situation figured out, i will do the bag test for you anyway.

[Fixer]

here you go Mike.
https://www.youtube.com/watch?v=IWFyj-Al18o

[MPDano]

Nice! Love the vids for proof. Now put some wheel center caps on

[Fixer]

Originally Posted by MPDano

Nice! Love the vids for proof. Now put some wheel center caps on

Thanks Leo,

You know i've read too many 911 RSR 2.8 articles to do that!

[Danglerb]

Originally Posted by The Fixer

here you go Mike.
https://www.youtube.com/watch?v=IWFyj-Al18o

Thanks, more of a steady stream than I would have guessed.