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 Post subject: b230 pcv options for ventilation hose delete
PostPosted: Tue Sep 25, 2012 11:16 am 
Vmax 200mph w00t!
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Joined: Mon Apr 19, 2010 4:21 pm
Posts: 265
Location: Saskatoon, Sk
Hello all!

I'm getting ready to drop a holset into the 940, and i'm wanting to delete the ventilation hose that goes from the breather box to the intake elbow.

In the past, deleting this hose has been a major cause of grief, as my b230 likes to have a lot of crank ventilation.

So i'm doing some research into other options.

Does anyone have some wisdom on this topic? I've considered tracking down a vented oil cap, but i'm still not sure how to plumb it properly.

I'm not opposed to some sort of catch can setup.

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94' 944t "The Good One"
87' 780 5.0L V8


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 Post subject: Re: b230 pcv options for ventilation hose delete
PostPosted: Wed Sep 26, 2012 7:17 am 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Wed Dec 21, 2005 8:40 pm
Posts: 3482
Location: Calgary, Ab
My opinion:

Don't vent from the head. This requires that gas come up through the same holes that the oil needs to drain back to the block through. The gas will win - I have non-Volvo proof. The older engines were done like this but they're also notorious for puking oil out the vents when the engine ages.

Using the stock oil separator has always worked well for me. I am also a big believer in burning those blowby gasses in a street car. They stink if you vent them to atmosphere... If you're not getting the oil control you need from the oil separator you can add a catch can, but it's still a good idea to draw that slight vacuum from the compressor intake and let the engine burn up the blowby. Besides being awful for the environment, this junk stinks and you'll smell it all the time - through your AC, sitting at lights, when you park your car... Draft tubes went out in the early '60s for a reason.


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 Post subject: Re: b230 pcv options for ventilation hose delete
PostPosted: Wed Sep 26, 2012 11:43 am 
Vmax 200mph w00t!
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Joined: Mon Apr 19, 2010 4:21 pm
Posts: 265
Location: Saskatoon, Sk
I did run a catch can at one point in time. It was inline with the breather box, such that oil vapors would not get sucked into the intake tube.

It helped but i think the diameters of tube i used at the time were too small.

however...this still doesn't solve my problem of removing the hose.

I think there's a way to suck pcv fumes out through the exhaust, i'll look into that...

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94' 944t "The Good One"
87' 780 5.0L V8


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 Post subject: Re: b230 pcv options for ventilation hose delete
PostPosted: Thu Sep 27, 2012 4:57 am 
Haha, I just built a W24 Octo-Turbo, now what?!
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Joined: Wed Dec 21, 2005 8:40 pm
Posts: 3482
Location: Calgary, Ab
Yeah, I know it doesn't help you get where you want to go - I'm a believer in using the pre-turbo suction for the performance and "environmental" reasons I specified - sorry. If your ventilation system is very efficient you can vent to atmosphere, but you're still going to get that smell unless the engine draws it in and consumes it.

You can get the exhaust to draw out the fumes but only under certain special conditions: the exhaust has to be under partial vacuum. Practically speaking, this means inside the collector of a naturally-aspirated header, without an exhaust behind it. i.e., on an old-school drag car that operates on one of the few tracks that still allows unmuffled cars on the track. Even the best post-turbo exhausts have a little backpressure and have no sources of vacuum (as you'd find in a good tuned header), so they don't make suitable ventilation syphons.

If I may ask, what is your reason for not plumbing it to in between the air filter & turbo?


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 Post subject: Re: b230 pcv options for ventilation hose delete
PostPosted: Thu Sep 27, 2012 10:18 am 
Vmax 200mph w00t!
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Joined: Mon Apr 19, 2010 4:21 pm
Posts: 265
Location: Saskatoon, Sk
That makes sense, i've always wondered about how people accomplish negative pressure in the exhaust...i imagined it to be some sort of venturi flowtube that you'd have to put inline with it.

I want to delete the hose for two reasons, the first being that the inlet to the holset (hx35w) is about 4" across, i'd like to not retain the stock inlet elbow as it's going to have to be reduced greatly.

The second is that i'd like to ditch the AMM and go to a MAP setup in the future, in which i would put a 4" filter directly onto the turbo inlet.

I suppose in the interim i could come up with a custom 4"-3" 90 degree elbow (I have a 3" AMM) with an inlet for the breather hose.

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94' 944t "The Good One"
87' 780 5.0L V8


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