WBX breather tower and oil coolers on an updated engine

[silverbullet]

Question? How necessary is the breather tower if you run an oil cooler and modern semi or full synthetic oil in a wbx?

As I see it, the tower does two jobs. Firstly it acts as a condensation recovery device, allowing oil vapours to condense and drain back into the sump, minimizing the amount drawn into the engine (oil effectively reduces the octane value of the inlet charge)
Secondly it contains a (E D I T) valve device, which appears to prevent vapour and blow-by gases from being drawn into the inlet at high vacuum i.e. when the throttle is closed at idle or on the overrun.

The need for the first point I can see as necessary back in the Castrol GTX days, but that was 40 years ago and oil technology has come a long way, with oils that are far better at resisting evaporation at higher operating temperatures.

Add an oil cooler into the equation (other than the stock interwarmer) to get stable oil temperatures and the tower starts to look like a hangover from another age.

Our old friend the Subaru EJ22 has no such thing, just a chamber in the crankcase behind the flywheel that ventilates the engine - along with two rocker box vents - and all three combine at a compact PCV that then connects direct to the inlet plenum. I think this is the earlier EA pushrod engine:



PCV valve to the right of the blue throttle pot:



The chamber is the long cover on the right hand side of the pic on an EJ:



I ask all this because I think I will have to delete the tower on an engine I am playing with on the bench; I am running out of space for all the fun stuff...

[silverbullet]

Before I left work I quickly sawed the top of a damaged tower:



I wonder how many are like this and no longer have a diaphragm in the top? Most, I bet.

[itchyfeet]

As you say pcv diaphram is probably gone on most so it's no more than an open crankcase vent.

Bin it and use a pcv off something similar like you suggest is probably a good thing.

you could trial it on your van easy enough first.

[silverbullet]

I reckon a straight copy of the subaru system complete with rocker box vents should do it.

[itchyfeet]

No other vent in wbx that I can think of, getting air flow right anywhere with multiple vents can be hard.

I wonder if you can just copy that or if it would be better to just go for a simple single crank vent.

If you want to get clever I'd say you would want to get an anemometer rigged to to check flow directions.

[silverbullet]

I think the lack of rocker box vents its a historical thing, in the same vein as VW keeping the 69mm crank for as long as they did and thinking that it still made for adequate performance.
Positive crankcase ventilation shouldnt be too hard to get right and might even bring side benefits.

[Aidan]

weird thing is that wbx still pass emmissions when they are all going to be effectively unvalved now, wbx tolerant of effective low octane value and HC levels not too elevated ?

doesn't the chambered area in the block on the scooby do what the tower does on the wbx - we changed to the alloy cover as plastic one fitted had wept on the quadcam, hopefully that will stay oil tight
tsr installations I have seen just bung up all these pipes on the scooby and fit little filters on the outlets on the cylinder heads, the right side one always weeps oil because it's a flow system as Ian's illustration shows

[silverbullet]

Maybe its more because of modern oils stability rather than the engine itself?
The EJ chamber is only an enclosed volume that allows case internal pressure to balance out. Its not baffled as such and has a pretty small port to prevent oil asiration (about the size of a fingerprint)
As for TSR... my one (now in Sallys Westy) actually has all of it intact because it has the early inlet pipe that suits T3 installation.