Oil Blow Back into my Turbo..........

i knew it was a one way valve. and the whole idea of the system is to suck oily vapours out of the crank case.

i can't see how its going to suck vapours out if theres no vacuum applied to the system (which is what the diagrams show in that link that was posted for a turbo setup). essentially its letting the crank case breathe but its not pushing/pulling the vapours into the catch can. the only momentum is from the movement of the crank.

There needs to be some sort of vacuum in the crankcase for the system to work and if the pipe from the manifold is not used then theres no way that the case is going to be vented properly.

I'll have to pull my PCV valve out and have a look at the little guy. I might put an air compressor on the end and pump it up to 10 psi and see if it will hold pressure.

If the check valve for the brake boost can hold pressure then theres no reason why the pcv valve van't hold the same pressure. if the pcv valve doesn't hold pressure then i'll just use a check valve from the brake booster setup in its place and just put a breather on the top of the valve cover. at least that way there will be vacuum in the system at some stage.

Luke - Breather is bad cos it can allow water vapour/moisture into your engine.

The PCV setup for turbos is on the link i posted.
It has a the catch can version, breather version and standard straight to throttle version.

i used the catch can version and it works fine. I get no blow-by

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Originally Posted by Limbo

Luke - Breather is bad cos it can allow water vapour/moisture into your engine.

The PCV setup for turbos is on the link i posted.
It has a the catch can version, breather version and standard straight to throttle version.

i used the catch can version and it works fine. I get no blow-by

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that and its illegal for emissions purposes. Just keep it hooked up to your intake arm , NA or boost guys :)

IMO, its got the same probability of getting water when compared to getting air from your car air filter, which is usually placed closer to the front of the engine bay where debris, water and other bad things can reach.

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Originally Posted by bennjamin

that and its illegal for emissions purposes. Just keep it hooked up to your intake arm , NA or boost guys :)

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on boost however, connect it before the turbo i reckon. :thumbsup:

Dont' want a pressurised AND sealed crankase at the same time.

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Originally Posted by JasonGilholme

on boost however, connect it before the turbo i reckon. :thumbsup:

Dont' want a pressurised AND sealed crankase at the same time.

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I agree with connecting it before the turbo. Having a breather means you get crankcase vapour in your engine bay. Personally, I'd rather breath the exhaust gas from a car with no cat, rather than breath crankcase vapours. And this is coming from someone with a chemical background. Crankcase vapour is very very nasty.

Aaronng - agreed.

Ben - yeah i know its illegal, forgot to add that, thought it was a moot point.

limbo can you draw up / or have a diagram of how this system works compared to the stock PCV system ? Interesting to compare.

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Originally Posted by bennjamin

limbo can you draw up / or have a diagram of how this system works compared to the stock PCV system ? Interesting to compare.

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Essentially, in a stock car, the intake manifold and the intake arm are under a slight vacuum when you are at full throttle (because air is sucked into the cylinder at a rate higher than the intake arm can supply it). So you get proper flow of the PCV system.

In a turbo car, intake piping after the turbo and the intake manifold are under positive pressure, so instead of crankcase vapour flowing out and into the intake manifold, the higher pressure stops proper crankcase vapour flow. So the PCV line and rocker cover line has to be plumbed back into a section that is below the pressure of the crankcase. That's why they suggested the piping before the turbo.

also, if the valve cover line is plumbed back to a position before the turbo, and your worried about extra blow by from higher cylinder pressures, you can run a catch tank the same way as you would on an NA setup. (between the manifold and the PCV valve.)

This is how i'm gonna do mine when the turbo is in.

both of the hoses here have been routed back to the intake arm.. the one from the head and valve cover.. i guess because the manifold having boost at some times rather then vacuum this is why it was done this way
http://i261.photobucket.com/albums/i...g/IMG_2227.jpg

wow.

It is NOT a one way valve. is it a HOLE. Nothing more. Sometimes the engine needs to inhale air, sometimes it needs to expell air. This is a relief port. SIMPLE. It is common practice to plumb 2 or 3 extra ports into the valve cover, with baffles, to improve engine health and breathing.

Plumbing the port into the intake arm will allow the engine to 'evacuate' and scavange oil vapours. It is the ideal setup. Some people plumb this port into there exhaust in other configurations...

Leaving this valve venting to the atmosphere will increase crank case pressures, cause a little more stess on the rings, but ultimately, as long as it can vent, it will not cause any noticeable to msot mild setups. maybe in 100km's it might induce ring wear, but nothing more.

Ben; Citing wikipedia. :thumbsdown:

Once again, this is not a PVC valve.