Going to make regular posts over the comming weeks, with modifications you can do at home, cheap and easy and most of all give you a bit of fun.

first one is why you dont need a wanky show off valve, your factory bov is more then adequate to hold onto big boost.

the regular factory "bypass valve" (Blow off valve- BOV) would normally hold manifold pressure for up to 1.2 bar of manifold pressure (give or take a few kPa).

as soon as you increase your boost over 1.2bar the spring pressure contained in the diaphragm is allowed by design to be overcome by the manifold pressure.

the trick to increasing the holding pressure of a standard BOV is to block this hole-



to do so,
1. Remove the BOV from the intercooler
2. Disconnect all hoses
3. Tap the hole below



4. Once tapped, insert the grub screw and wind home with an allen key
5. Reattach hoses and reattach to the intercooler



enjoy!

disclaimer-

If you are clueless.

Do not attempt any of these modifications.

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Long live the WRC

Only took you a year to finally start this! haha good work!

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MY00 GT Forester with STi goodies

tell me about it!



also, up-side to the mod is much faster opening and closing with the pressure differentials.

99% of after market bovs rely on spring pressure alone to hold a bov shut, without a diaphram, they are only as good as the china spring thats inside them.

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Long live the WRC

This also works for my08+ and other plastic bov cars too.

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Long live the WRC

Is there any downside/increased risk of component failure from doing this?

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[COLOR=RoyalBlue][B][I]Titanium Reinforced[/I][/B]
MY00 Impreza WRX | MY11 Liberty GT Premium[/COLOR]

What size grub screw?

....

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www.perth-wrx.com

The same size as to whatever tap size you use?

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[SIGPIC][/SIGPIC]

It allows the factory BOV to hold onto bigger boost pressures.

It won't sound any different, it simply allows you to save $$$ by not spending money on a aftermarket BOV when you run additional boost.

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[SIGPIC][/SIGPIC]

Any difference in a wrx vs sti bov ?

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There's a hoon in every Typhoon