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Old 11-28-2012, 10:35 AM   #1
RYAN007R6
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I got a Perrin fmic from one of our members here. Came off an 07 sti with around 530whp....yeah I know.
He had the blow by set up and Tial bov that came with.
I blocked off the MAF relocate and am running the Tial.
I now have surge going back into my turbo and only some of the boost actually blowing to atmosphere. I am thinking my spring it to strong and my boost isn't strong enough to open the bov...
I also have a pretty long vac hose to the bov, and its off the "T" fitting that goes to the boost gauge. Tial says to have a DIRECT hose to the bov....I am wondering if I should go with a lighter spring?? Or just shorten and go to direct source for my vac supply for the Tial.
Any HELPFUL comments would be greatly appreciated. Thanks!!
Ps my sti is an 05
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Old 11-28-2012, 10:46 AM   #2
Omega_2nr
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Most likely the spring is too stiff for your application.

<cue comments about the stock BPV>
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Old 11-28-2012, 10:51 AM   #3
RYAN007R6
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Quote:
Originally Posted by Omega_2nr
Most likely the spring is too stiff for your application.

<cue comments about the stock BPV>
I was thinking the same....
About the stock bpv, it doesn't exist. Had an aps 50/50 when I bought it. When I went to the Tial I blocked off the diverter hose. It will run rich for the split second I shift. But not to worried about that as of right now.
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Old 11-28-2012, 11:21 AM   #4
Omega_2nr
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Fair enough. Considering you're getting surge and the BOV doesn't sound like it's opening much, and it was mounted on an STi boosted to the moon, it's pretty certain the spring is too stiff.

If you can't get another spring easily, try using that APS 50/50 if it can bolt on to the FMIC piping (does the piping use the same flange as on the stock TMIC/whats on the APS?).

I suppose you could mess around with the vac hoses (for little to no $$)....so you could also try that first and see if it alleviates the problem - doubt it will though.
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Old 11-28-2012, 11:36 AM   #5
RYAN007R6
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Quote:
Originally Posted by Omega_2nr
Fair enough. Considering you're getting surge and the BOV doesn't sound like it's opening much, and it was mounted on an STi boosted to the moon, it's pretty certain the spring is too stiff.

If you can't get another spring easily, try using that APS 50/50 if it can bolt on to the FMIC piping (does the piping use the same flange as on the stock TMIC/whats on the APS?).

I suppose you could mess around with the vac hoses (for little to no $$)....so you could also try that first and see if it alleviates the problem - doubt it will though.
I don't have the aps anymore...and the Tial is a v band flange....so nothing else will be able to bolt up to this application.
I went on Tial's website and the biggest spring they have is rated at 12psi....its the pink colored one. So I took apart mine and it had the pink colored one in it. This is where the confusion starts; how did he run 30psi on a 12psi spring? Unless I am reading their specs wrong.
This is all being done with a "Q version 2" Tial bov
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Old 11-28-2012, 01:18 PM   #6
Wicked Innovation
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First, yes run a large diameter line DIRECT to one of the ports on your intake manifold. No tees or any of that.

Second, the spring has nothing to do with your boost levels. You have to run the -11 or -12 psi spring on a MAF subaru to keep the valve closed at idle, the spring is for vacuum pressure. Its what keeps the valve closed when vacuum is pulling up on it.

With any 'correctly' set up atmospheric valve on a MAF car you are going to get surge at part throttle.

Wicked M@
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Old 11-28-2012, 02:24 PM   #7
RYAN007R6
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Quote:
Originally Posted by Wicked Innovation
First, yes run a large diameter line DIRECT to one of the ports on your intake manifold. No tees or any of that.

Second, the spring has nothing to do with your boost levels. You have to run the -11 or -12 psi spring on a MAF subaru to keep the valve closed at idle, the spring is for vacuum pressure. Its what keeps the valve closed when vacuum is pulling up on it.

With any 'correctly' set up atmospheric valve on a MAF car you are going to get surge at part throttle.

Wicked M@
Should I also shorten the line? It's about 2 feet long now seeing how I have to go across my engine bay. The location of my bov is not in the stock location. It is located over my abs unit.
My bov also sounds like it isn't staying open long enough if at all when I shift. On hard accel, after I shift it stalls the turbo, then blows off a little then shuts very quickly
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Old 11-28-2012, 10:21 PM   #8
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Length of the vac line shouldn't make much of a difference. At idle, what does your boost gauge read in/Hg? Whatever it says, reference it here and get the appropriate spring.
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Old 11-29-2012, 12:23 PM   #9
Wicked Innovation
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The spring needs to be the -11, anything softer and it will open under decel and will stumble/stall recovering the idle.

The length and diameter of the line do make a difference, run at least a 4mm line as short as possible.

That operation is normal with the heavy spring and letting off under part throttle or with a setup making lower amounts of airflow and boost pressure.
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Old 11-29-2012, 12:27 PM   #10
WhatTurboLag?
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I'm running sd but still have my maf shims in because I'm using the stock intercooler flange so when it blew off at part throttle it whistled and sounded gay lol

Comp surge ftw
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Old 11-29-2012, 04:24 PM   #11
RYAN007R6
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Thanks guys for the input. I am gonna bring it into the shop tonight after work and mess with it a little. I will keep you guys posted. Thanks again
-Ryan
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Old 11-30-2012, 09:40 AM   #12
RYAN007R6
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Brought the car in last night. Shortened the vac hose to the bov and ran it from the 1/4" fitting on the front side of the manifold. Took it out, and the comp surge was gone. Still got the lesser spring on the way, thanks to a fellow member.
Gonna try it out for shi** and giggles. Thanks again for all the help. It was definitely useful.
-Ryan
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