Theories on crankcase vapour and pre-detonation...

Ben · Post by **Ben** » Sun Apr 19, 2009 4:00 pm

Heat shield is same as fitted to the turbs tex too

SCOOBIDOO · Post by **SCOOBIDOO** » Sun Apr 19, 2009 5:39 pm

Sounds to me that no one like,s to hear the truth,i say it how i see it.
Constructive or not , get over it,or grow a thicker skin,i have to everytime i see rubbish quoted on this forum. And they are always right ....as we can see.

nncoolg · Post by **nncoolg** » Sun Jan 25, 2015 7:21 am

Okay, so here goes me opening up an old thread and potentially a big can of whoop-ass it seems;

Gannon if you're still around, how did your oil seperator work out? These are quite popular now on subies especially from Crawford performance but I am wondering if you had any moisture collect inside the can and therefore drain back to the sump which is something that no one will want to happen?

Serious question here too guys, they seem like a great idea but the condensation thing terrifies me. Afterall there's always mucky water in the bottom of a catch can and ain't no engine got time fo' dat!

Post by **TOONGA** » Sun Jan 25, 2015 11:10 am

In theory the PCV removes excess vapour from the engine, that is if it is working properly.

It will not take the oil droplets out of the vapour.

I have a catch can connected to my breather lines before the PCV on my carbied EJ22.

It is filled with stainless steel dish scrubbers to catch excess oil vapour and has never had water in the bottom of it.

There is a small pool of old oil in the bottom of it, but that can stay where it is

TOONGA

nncoolg · Post by **nncoolg** » Sun Jan 25, 2015 3:02 pm

I suppose it depends on where the can is situated and if it is the same temp as the engine and for as long as the engine...

Post by **TOONGA** » Sun Jan 25, 2015 4:49 pm

True the futher from the engine and PCV the more chance of condensation when the engine cools.

This is my set up

TOONGA

Gannon · Post by **Gannon** » Thu Jan 29, 2015 8:41 am

I missed this thread the other day.
I suspect that once at operating temperature, the water should be a vapour and make its way into the intake. My catch can was on top of the engine so was always plenty warm.

nncoolg · Post by **nncoolg** » Thu Jan 29, 2015 9:21 am

Yes Gannon, you are probably correct but you wouldn't want condensation forming during cool down and returning creamy gunk to the sump.

I have also found something interesting, Mann , the makers of the progeny AOS, recommend using a one way valve on the drain if draining back above oil level so that gasses don't travel up to the bottom of the can.

nncoolg · Post by **nncoolg** » Fri Jan 30, 2015 2:44 am

This is an idea I had a while ago and have been trying to work out the kinks in my head:

http://www.subaruxt.com/forum/viewtopic ... rd#p148646

It seems the idea (or adaption of someone else's) seems solid so long as it mounted on the engine and has a check valve so it stops the flow out of the crankcase breather but allows oil drain back.

I wonder is that why Subarus all pool oil up in the compressor housing, because the oil drain is above the sump level and crankcase vent gas fights against the drain, aiding oil past the turbo seal plate?

...interesting stuff!

Gannon · Post by **Gannon** » Fri Jan 30, 2015 8:29 am

Thats exactly how mine was constructed, but I see your point about the one way valve to stop air rising through the rear block vent. Looking at it now I should have set it up more like factory so that fresh air comes in one side of the engine and the mixed air goes through the separator, but with one way valves to stop backflow when on boost.

I doubt the turbo seal is an issue, because the air pressure inside the compressor housing should always be higher than crankcase, unless something is blocked

Gannon · Post by **Gannon** » Fri Jan 30, 2015 8:39 am

I just re-read the whole thread....
Hahahah that brings back memories..... an injector in a POD filter. Hahahah

nncoolg · Post by **nncoolg** » Fri Jan 30, 2015 6:21 pm

Yeah I'm not sure about the whole turbo thing aye, turbos don't see much boost time when driving normally, well the way I drive anyway.
I reckon most of the time the crankcase pressure would overcome the post-cartridge oil pressure.
Some thought I will take...

nncoolg · Post by **nncoolg** » Fri Jan 30, 2015 7:04 pm

And...injector in a pod filter? Huh?

Gannon · Post by **Gannon** » Fri Jan 30, 2015 7:23 pm

Scoobidoo was bragging at some stage years ago that he had got to the limit of the EA82 ECU and injectors and rigged a fuel injector into the centre of his pod filter and had it come on at 10psi via pressure switch.
I had a dig at him about it, hence his hostility at my catch can in this thread

nncoolg · Post by **nncoolg** » Fri Jan 30, 2015 9:04 pm

Ah huh. Wouldnt be much fuel vapor left once it traveled all the way from the pod, through the turbo, the manifold into the engine!