Crankcase pressure

[Andy from the block]

After my turbo began smoking about 3 months after it had been
professionally rebuilt, I took it back to the rebuilder who advised me
4age turbo setups are renown for smokey turbos and part of the
problem is with relieving enough crankcase pressure.
He advised me to reduce the oil inlet diameter to 2mm which I did.
And also to get another rocker cover with a crankcase vent (which
should be in the mail headin to my house).
Ive read some articles on the internet of the benefits of having
vacuum in the crankcase in terms of helping promote engine efficiency
due to better piston sealing, many drag cars run electrical pumps to suck
crankcase pressure in the states, ive been told by my turbo rebuilder
that there should be a small increase in power in relieving crankcase
pressure, not to mention help with my oil leaks

I just wanted to discuss what you guys think are some options in terms
of relieving crankcase pressure and which ones are good/bad and why.
Some setups im aware of are:
1)outlets going to intake manifold (stock setup usually)
2)outlets going to breather
3)outlets going to oil catch can
4)outlets going to sealed catch can with vacuum being drawn from turbo inlet
5)outlets going to electric vacuum pump
6)outlets going to belt driven vacuum pump
7)outlets going to check valve on exhaust manifold (just after collector)
to use exhaust vacuum to suck pressure out

At the moment Im just running setup number 3, but Im very interested with the
last setup cuz many people have had good results in N/A and supercharged
cars in the states..could this setup be used on a 4agte?
Any thoughts or experiences appreciated

[wde_bdy]

How is the crankcase pressure supposed to have an effect on your turbo? Only thing that impacts it should be the oil pressure you are running.

Callum

[vvega]

How is the crankcase pressure supposed to have an effect on your turbo? Only thing that impacts it should be the oil pressure you are running.

Callum

creates more pressure on the seals
and then they leak
just have a think abotu how they operate
they are not suposed to have have any pressure in the drain cavity or they will seap

v

[wde_bdy]

Very good point vvega, my common sense is on strike and I forgot about the oil drain.

[Bazda]

the collector is where all ur pipes merge to the flange so how can u put it after the collector??

[Andy from the block]

Ive read about system number 3 (outlets going to sealed catch can
with vacuum being drawn from turbo inlet) being good but having the
disadvantage of drawing contaminated air into the turbo inlet.
So I thought of a solution...(done before?)
(copy and paste address if it doesnt work)
Plumb a hose from catch can to turbo inlet with a small filter on the end
of the hose so the air into the turbo stays (reasonably) fresh.
What do you guys think?
PS: Diagram not to scale

[CozmoNz]

For that "small filter" you can use a carbie fuel filter. it should collect most if not all of the oil.

hey worse comes to worse, run 3-4 in a row

[vvega]

NOT TO SCALE
NOT TO SCALE
NOT TO SCALE

v

[Mr Revhead]

when i emptied my catch can on my 20v, it was full of water.
so my suggestion is:

make all hoses ut of the cover exit into a catch can that has a filter on top. no
lines into air intake.
the pressure in the crankcase will vent through the can and filter, any oil/water will be caught in the can.
only down side is a slight oil smell.

if you want a line into the intake, then maybe baffling the can so anything entering it hit the baffle, thatll seperate any (most) vapour/oil from the air and collect it in the can.

[Bazda]

when i emptied my catch can on my 20v, it was full of water.
so my suggestion is:

make all hoses ut of the cover exit into a catch can that has a filter on top. no
lines into air intake.
the pressure in the crankcase will vent through the can and filter, any oil/water will be caught in the can.
only down side is a slight oil smell.

if you want a line into the intake, then maybe baffling the can so anything entering it hit the baffle, thatll seperate any (most) vapour/oil from the air and collect it in the can.

spot on

[TWSTD]

I had the same issue with my 7afte in the carib. IMO it is essential to keep the PCV valve line plumbed in as the intake manifold vacuume actively relieves crankcase pressure. I run mine into a sealed catch can (filled with steel wool) then the cleaned air back into the intake manifold. That alone stopped 90% of the issues i had with smokey T25 in that car.

[matt dunn]

One of the main advantages of running a catch can is tgo stop the oil vapours entering the engine at all.
The oil vapours greatly reduce the octane rating of your air fuel mix and cause detonation which the computer compensates for and you lose power.

So why fit a can and then run it back into the system anyway????

Matt

[sergei]

Electrical vacuum pump? Will work great, but where to get it and what price?

[TWSTD]

So why fit a can and then run it back into the system anyway????
Matt

The catch can is essentially a condenser. It is filled with steel wool assisting the oil to condense into a liquid and pool in the bottom of the can. The cleaned air then passes back into the intake. I can assure you there is no oily residue on the inside of the line going back to the intake manifold as there used to be without the catch can in place.

On a side note, in some less fortunate places in the world it is against emissions laws to have an atmospheric venting catch can or breather line at all - they are required to be set up this way.

[evil_si]

just get your rocker covers modified, a put a breather port in both, rather than just the 1, use at least 1/2" ports and hose,
and make sure the catch can has a breather on it, or it wont do anything, will pressurise the system, a lot of the cheap ones dont have provision for a breather filter,

[vvega]

sorry twisted but while steel wool will take out the heavy particulates it will not remove all the mist and its the fine mist that polutes the charge
you need a proper air oil seperator for that

and no you willnot see a resdue in your pipes like but im quite sure that if you unplug it put a white tissue over the end and drive the car you will see discloration

it is however a good compramise and will ensure you dont get that horible oily smell that external catch cans come with



just my thoughts

v

[TWSTD]

.. a lot of the cheap ones dont have provision for a breather filter

A lot of the expensive japanese ones dont either, for the reasons i explained above, This kind of catch can is not supposed to have a breather on it as it contravenes emmissions regulations. These sealed types are designed to be put inline as a condenser. A catch can with atmospheric breather filter is of course not supposed to be an inline device. I actually run 1 of each kind in the caldina - that way you retain the benefit of the PCV system as well as preventing any oily vapour entering your intake system.

[TWSTD]

sorry twisted but while steel wool will take out the heavy particulates it will not remove all the mist and its the fine mist that polutes the charge

I actually ran an interresting experiment for a while before installing this catch can:

1) Install a clear fuel filter inline leaving the PCV valve in place.

2) Then run the car for a couple weeks - you will notice very quickly the build up of oil. Mine needed replacing within about 3-4 weeks.
3) Then install sealed catch can stuffed with steel wool or other similar material to aid condensation.
4) now (using a new filter) run one of those fuel filters again on the outgoing line from the catch can.

Result: COMPLETELY free of oil after 4 weeks of driving.

[vvega]

the vapour is made from 2 parts one been heavy mass the other been fumes

the heavy mass is from the oil getting churned
the fumes are from the hot rings and bore been cooled buy oil

you cannot easily remove the fumes and it is these that also cause the detanation issue

i must say i do like your experiment it proves you have no heaavy mass moving though the system

but just thinking about it the oily smell is also what your tring to remove as this is the fumes

do you think your steel wool removes the fumes ??

v

[Andy from the block]

just get your rocker covers modified, a put a breather port in both, rather than just the 1, use at least 1/2" ports and hose,
and make sure the catch can has a breather on it, or it wont do anything, will pressurise the system, a lot of the cheap ones dont have provision for a breather filter,

I just received my rocker cover I bought of trademe, its one
with twin cam 16 valve written in red. I compared it to my ze rocker
cover and the outlet is much smaller. Also, looking at the underside
of the covers I saw the ze one is much simpler in terms of plates/baffling
than the other cover. The differnce in design isnt gonna be a problem
would it?
Oh and how hard is it to modify the rocker covers to have additional
outlets?