Oil - Air seperators; what sort of gains?

[Cool Hand Luke]

What sort of gains would i be look at getting by fitting an oil air seperator? I know the basic principles on how they work, but have never really read anything (zoom did an issue with it but i cant find it!) that shows what performance gains are gotten from it.

[Busky2k]

I wouldnt think there would be a direct performance gain. The main reason you use it is so you dont get oil shitting up your intake/intercooler. Also the oil can contribute detonation on cars with alot of blowby, but i wouldnt go advancing the timing or anything like that after I installed a OAS.

[Brody]

As above,

Technical answer = less shit flying round.

[CMS Drifter]

Correction to all.

An oil/air separator simply allows your engine crankcase to "breathe" and separate oil from air before returning it to the intake.

With the parts moving inside the engine (pistons up and down) there can be a marginal amount of air displacement.

This air has to come and go from somewhere.... in standard form, there is a provision made, but can feed oily air back in to the intake.

By fitting an oil/air separator, it allows the oil to be removed from the air before returning back to the intake.

It also reduces crankcase compression that is caused by the displacement of air and blowby caused by worn pistons/rings

[JimX]

The oil/air separator doesn't allow the crankcase to "breathe", it's the holes in the cam covers which do that. Whether you have them feed straight back into the intake or plenum or through a catch can or separator or even just a breather filter is irrelevant, in all cases it still "breathes".

Busky2k's description sums up the oil/air separator's function perfectly, there is no need for a "correction".

[CMS Drifter]

An oil/air separator connects to your cam covers....

In the case of a SKYLINE it is fed back to the intake, there is only a small amount which is plumbed into the plenum via pcv valve.

Correction... addition what ever, bite me.

[J.B.E]

Originally posted by Busky2k

I wouldnt think there would be a direct performance gain. The main reason you use it is so you dont get oil shitting up your intake/intercooler. Also the oil can contribute detonation on cars with alot of blowby, but i wouldnt go advancing the timing or anything like that after I installed a OAS.

Busky2k is sorta right, the reason for installing a oil air seperator especially on race or high boost application cars is cause the oil that ends up being recycled back into the engine goes down and gets burnt with the gas, with it mixing with your gas it lowers the octain rating which causes detonation. so by installing 1 of these you will lessen the chance of detonation and run safer higher boost levels especially if you do hav blow by problems. So the only performance gains i could see would be very minimal.

[VLRB20DET]

How do you install either a catch can or oil/air seperator on a RB20DET, do you have to block off the pcv valve or not?

[rbs13]

instead of having the cam cover hose going to the plenum make it go to the oil catch can and on the other cam cover the one going to the intake just make that go to the oil catch can as well.. theres that way or.. leave the one in the plenum and make the intake hose go to the catch can instead.. if ya know what i mean??

[VLRB20DET]

so i just block off the the pcv valve then? or leave it connecteed and run 2 hoses form the rocker covers, what works best a catch can or a oil/air seperator?

[J.B.E]

I personaly dont see the point in havinin a oil air seperator if your only goint to run 1 of your hoses from your valve covers to the catch can, but yes VLRB20DET you just disconnect them from the plenum and the intake ducting and run them to your catch can, dont forget to plug the hole up that you've disconnected. Because on most R32 series valves covers the the connections are pointing in two different directions you could take them out and use the connections from a RB20DE which are just right angled connection and dont have the connector piece going between them you can point them in any direction you want, eg: to you catch can where ever you decide to put it.

Hope that helped

Soon as i get sum pictures from my camera to the comp i'll show you how i have mine.