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DZGunner · Joined: 18 Nov 2014 Posts: 191 Location: Great white north

Hey guys this started in another thread that got way off topic so i thought I'd start a new one to get us on a seprate track.

My question is: Is it really necessary to have the CCV go the the air box or is it ok to have it vent to atmosphere. All i mean to do is have the hose that goes from the AOS to the air box NOT go to the air filter box because my intake set up is different so i no longer have a spot to plumb it into. I now have a pod filter with an adapter because the OEM set up was messed up when I bought the car.

I've seen track cars on the internet that just had a small filter right on the AOS so i was pretty sure it would be ok to do the same until i got a few responses on this, i just mainly want to know why though. Thanks guys.

Rasta Monsta · Joined: 12 Jul 2006 Posts: 11733 Location: PacNW

The engine (and turbo drain/breather) is designed to have positive vacuum. This is important enough that some cars even have a belt driven vacuum pump on the crankcase.

Combustion gasses need to be purged from the crankcase (oil contamination shortens oil service life and I also believe accelerates the wear on our turbos), and seals work better when under a slight vacuum as well.

Is there some compelling reason you don't want it?
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Toofah King Bad

WeiBe (1987 924S 2.5t) - 931 S3

Dutch924-racer · Joined: 23 Jul 2007 Posts: 1081 Location: The Netherlands

you actually don't want the hot (and dirty) crankcase air in your inlet/ intercooler. It won't benifit the performance.
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937 trackday car
Series 2 engine
951S turbo and intercooler
Fast road camshaft
Forge recirculation valve + boost controller

DZGunner · Joined: 18 Nov 2014 Posts: 191 Location: Great white north

well mainly i don't know where to plumb it into, because like i said, the original setup has that big port for the AOS to connect to on the air box. Right now i just have a pod filter connected to the boot on the top of the fuel distributor so there isn't anywhere to have it routed to, that's the main reason.

Reason 2 is just that I've seen cars that have it vent to atmosphere, but i'm not sure if they were turbo or forced induction or anything so idk if it makes a big difference.

leadfoot · Posted: Fri Feb 06, 2015 10:49 am Post subject:

if you still have the 90deg rubber boot, get a short piece of tube and connect that between it and your pod (you can get silicon ones otherwise)... connect the 22mm pcv air line to this new tube via a nipple...
Stu
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...