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Old 01-07-2019, 11:36 PM   #5
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Join Date: Apr 2013
Chapter/Region: International
Location: Newcastle Australia
2005 EVO 8 WRX + STi

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Originally Posted by blackerst View Post
I disagree that crankcase scavenging is worsened given the stock design crankcase breather is T'd with one end going to the turbo inlet and the other to the PCV already, so scavenging off boost is already an issue with stock if what you say is true.
I would say here is "check your base assumptions". You are talking about a designed in fault on a pretty basic system. I would be backing Subaru to have got it right, and the rest of us to not know exactly what the core logic here is. I have gone for a basic solution of just putting a can in the existing vent lines to solve the problem. Disrupting the system further to, at best, get a smidge of off-boost octane back, whilst adding obstacles to flow as originally designed, seems a pretty pointless pursuit to me. But that's me.

Whilst I would say I have laid out my logic fairly completely and am probably at the limit of adding value to debate around other prospective 'solutions', I would suggest a careful look at the crankcase breather fitting first before jumping to conclusions. There is a chance it is not the same size fitting from the larger crank inlet to the two hose outlets.

Regardless, the problem Subaru is trying to solve is blow-by, not suction. So maybe T-ing the PCV across is an answer as blowby will get through the can and into a place where it doesn't really matter which way it goes. Do let us know what you find out .
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VinceS2 is offline   Reply With Quote