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'12 WRX Sedan
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218 Posts
Discussion Starter · #1 ·
Ok, so i am pondering turboing the RS and i am trying to price everything out, and i think i need a new spring for my TiAL bov but i dont know which one. does anyone know about how much vacuum our engines pull so i can get the correct spring?

Thanks everyone!

Luke
 

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'12 WRX Sedan
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218 Posts
Discussion Starter · #3 ·
Engine Vacuum Reading / Color Use Spring
Between:
- 22 and -23 in/Hg Pink -12 Psi (-24 in/Hg )
-18 and -21 in/Hg Un-painted -11 Psi (-22 in/Hg )
- 14 and -17 in/Hg White -9 Psi (-18 in/Hg )
-10 and -13 in/Hg Black -7 Psi (-14 in/Hg )

thats from tials website, so i should def use the pink one? how do i even measure engine vacuum?
 

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2015 STI Crystal White Pearl
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1,931 Posts
sorry, you want the unpainted spring by lookling at the chart. if you look at the left of what you typed, that's your vacuum. our cars idle at -20in/Hg. the unpainted spring has a range of 18-21. that's what you want because -20 falls in that range.
 

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456 Posts
Back from the dead, because I need some insight. I just got an original TiAL 50mm BOV rigged up on my OE STI TMIC with the P&L kit. It currently has an unpainted 11 psi spring in it, and it seems to be opening ever so slightly at idle.

I have a low mileage EJ257 from an '04 STI, but I don't think it would produce any particularly stronger vacuum than a higher mileage motor? Should I bump it up to the 12 psi spring? Who's running one? Thanks!
:)
 

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456 Posts
Thanks so much for the feedback guys, much appreciated.

The slight opening is affecting my idle slightly, not to the point of stalling, but close enough to be annoying. I get slight idle surge but only over a few hundred rpm, nothing too crazy.

Great idea about adjusting AVCS a little, didn't even think of that. From what I gather, the 12 psi spring is a big difference from the 11 psi spring, so I think you're right that it would cause compressor surge.

Thanks guys!
:)
 
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