PCV system - interesting read

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Looks interesting!!

You gonna give it a go??

I thought about using a vacupan system (using the exhaust to draw the vac).
It would work but needs to be after the muffler, which means long plumbing!!

Woth the effort to test imo!
 
I'm thinking of grabbing another VC and trying this out Barry. Can't hurt after all.
I might have to tap a boost gauge into the VC first to see what is happening in there I think.
 
I'm maintaining the PCV to the intake manifold, but using a -10 fitting to route the rocker cover outlet to an oil/air seperator that will be filtered to atmosphere when on track duties. Otherwise the can will route to the intake pipe as per stock for road use.
 
I don't understand why keeping the crankcase in vacuum helps make the engine run cleaner?

I understand that it's not good to have it pressurised because you could blow seals out etc

But wouldn't the pressure differential either side of the piston rings become even greater by keeping the crankcase in vacuum? Encouraging increased blow-by....fuel in oil/dirty oil etc?

This is confusing. I thought that venting crankcase pressure to atmosphere (catch can) would be the best thing to promote a clean engine (not so environmentally friendly though).

I can understand that maybe the factory PCV outlets are a little too small to scavenge all of the blow-by, so why wouldn't it be better to run similar enlarged lines to atmosphere (catch can)?
 
ENGINR said:
I'm maintaining the PCV to the intake manifold, but using a -10 fitting to route the rocker cover outlet to an oil/air seperator that will be filtered to atmosphere when on track duties. Otherwise the can will route to the intake pipe as per stock for road use.
Click to expand...

Hey mate, when you say oil/air seperator, thats just a catch can hey?
Or am I missing something? lol
Maybe you guys have some fancy technologies I'm unaware of!
I wanted to use a peltier condensor for this job but I wasn't bothered to stick a DC-DC converter in as the only peltier condensors I had ran on 24VDC.
I figured if it really worked people would already be doing it. lol :p
 
Yeah catch can/seperator pretty much means the same thing. Some have baffles and some dont. The basic princible is that once the air exits the rocker cover and enters the 'can/seperator' the heavy oil, fuel and water vapour particles drop to the bottom of the can, and the air (minus a lot of those particles) either exits the top of the can to atmosphere via a filter, or is taken back into the intake system. This means that the amount of oil/fuel/water molecules re-entering the intake system is minimal, or in the case of venting to atmosphere, zero.
 
An oil air separator will have baffles, where as a catch can generally doesn't. Doing something as simple as throwing some steel wool in to a catch can will help the oil/water vapors condense, and hence separate the oil from the air.
 
Steel wool corrodes, and the stainless type breaks down into small particles. Be carefull what you put in there.
 
Missile said:
An oil air separator will have baffles, where as a catch can generally doesn't. Doing something as simple as throwing some steel wool in to a catch can will help the oil/water vapors condense, and hence separate the oil from the air.
Click to expand...

I tried that. It didn't make any difference on my car. Just 'by eye' the amount of vapor going through the inlet and outlet ports looked much the same.
Besides there was never any deposit, at all inside the can, even after months of operation.
That was with both the PCV valve and side connection routed through it as well.
I just chucked a small cotton filter on it and vented it to atmosphere instead.
I always wondered what the point of catch cans without baffles were. Still do actually.
 
EVO-00X said:
Steel wool corrodes, and the stainless type breaks down into small particles. Be carefull what you put in there.
Click to expand...

Really? Eek! :unsure:
I used the stainless one thinking that it'd be rather inert.
Does it just get brittle with all the heat cycling and just break up into little bits or something?

Rob what if you got a normal unbaffled catch can, routed the inlet hose to the bottom of the can and half filled it with oil or water?
Passing through the liquid, even if it is hot, I'd assume that most of the vapour would condense?
But then would that pose as a restriction between the crankcase and atmo/inlet? Not allowing it to vent clearly when needed, rather it has to push its way through the liquid?
The only other downside to this if the liquid bubbles up too much and goes to the outlet port, could result in hydrolock.
 
okay this looks interesting.... might try it.. wont take long to take off anyways....
 
JayRome said:
okay this looks interesting.... might try it.. wont take long to take off anyways....
Click to expand...

I must be missing something. :huh:
Jay do you know why this system is a good idea?
i.e What makes you wanna try it out?
 
Since the turbo is sucking so much air from crankcase enough to create 7in of vac, wouldnt all the oil particles drop the octane level which could cause the engine to detonate if timing remains the same?
I think this setup would work just as good if all the lines went to catch can first and then back to intake pipe and the air would contain less oil vapour particles.
 
GSR said:
Since the turbo is sucking so much air from crankcase enough to create 7in of vac, wouldnt all the oil particles drop the octane level which could cause the engine to detonate if timing remains the same?
I think this setup would work just as good if all the lines went to catch can first and then back to intake pipe and the air would contain less oil vapour particles.
Click to expand...

Phew! I thought I was going crazy ahaha :p
 
Actually you could say the same thing about when he gets 4psi of pressure in there under boost. You would think that would push a heap of oil out? The 4psi reading was taken in the valve cover after all.
Don't forget that he has left all the original baffles in place to help combat oil loss into the inlet tract.

I have a small plastic fuel filter in my line from the vc to the intake pipe and I get very little oil build up in there, even with a 270000+ km engine running over 30psi everytime I take it out.
I'd be guessing that the vacuum that is created in the pan actually helps to seal the rings minimizing blow-by.

I can't see why you couldn't run it to a catch can first to try to remove as much oil have as possible first though.
Regardless, I'm going to try this anyway. Can't hurt!
 
Cool, let us know how it goes Tim :)
Hopefully it works out for you.
It is an interesting topic.
 

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