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AOS/ Catch can 08-14 STI

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Has anyone installed either a Grimmspeed AOS or 3 port catch can on an 08-14 STI? Im finding it hard to pinpoint the routing for the pipework at the PCV end.. Am I right in saying that the PCV pipe is removed where it joins the turbo inlet, block off the turbo inlet, then run the new pipework via a 2 way connector straight from the PCV pipe back to the can?  - Im happy with the other two locations, but that PCV setup seems to vary slightly from 08-14 to 15+... most of the clips online are from 15+ or WRX only.


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Most "clips" will show the US spec model which has an additional sensor in the pcv line to the turbo inlet.

If you are leaving the pcv valve in place just take the feed from the "Y" pipe that would have gone to the tuebo inlet and feed it to the grimspeed.

Below is my setup using the TomiokaRacing version which only has two connections (one feed; one return) so the feeds from the crankcase (PCV Y pipe) and the heads are tee'd together in front of the inlet manifold.

THe original pipe from the heads was cut and sections reused - hence the additional couplers.



OEM pipe and joiners.jpg

aos.jpgCrankcase breather.jpg

UK spec PCV "Y" pipe

top left to PCV valve

top right to turbo inlet pipe - replaced with feed to AOS

bottom connection to crankcase


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Thats great, exactly what I was looking for, Thanks. 

Really neat install aswell, first one I've seen with the PCV Teed in with the crankcase. I guess the same could be achieved with just a 2 port catch can, I'm not sold on that Grimmspeed AOS..

Thanks for your help.


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Posted (edited)

Just one other question, did you need a reducer coupler for attaching the hose to the PCV assy at the rear or is that also 13mm?


(I'm not in the country just now otherwise I'd physically look myself, just want to make some purchases ready for when I get back)

Edited by JSOCK

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