Cars that go Psssh
 

Searched forums, couldn't find much on this.

[url]http://www.gofastbits.com.au/[/url]

"Leaking factory (BOV) valves: Some factory valves have systems designed into them to crack open at high boost, in order to protect the engine from boost spikes. They do this by designing the pressure to be unequal on the top an bottom of the valve, thereby overcoming the spring at a certain pressure.

If you are intentionally raising the boost level, this is bad news as the valve will begin to leak pressure. Examples of factory valves which exhibit this behaviour are the Subaru WRX MY95-98, and MY01-04, Mitsubishi Lancer GSR, and Nissan 200SX to name a few. Replacing these valves when increasing the boost is a good idea."

I thought (loud) aftermarket BOV's are a load of wank, we all know they don't do anything for hp but do some stock bov actually leak (on purpose) under higher than stock boost (due to mods)? Never knew this...

I'm just starting to mod my car but don't want to waste money...according to the aformentioned paragraphs, the stock bov in my MY00 will be fine...

Just wont be a "car that goes psssh"

Have most people got an aftermarket BOV regardless of other mods? Is it purely for show? Just seems to me it's a mod that is easy and cheap, adds no performance and one that the cops will take pleasure putting on a sticker for. Doesn't make sence!

Its for wank factor, if anything the car will run worse when it goes "PSHH".

Yeah will run rich if you still rely on factory computer and AFM.. .once u go MAP you can PSSHHHH alll you like.

In fact my car ran perfectly on MAP even with a totally burst intercooler pipe silicone joiner.

you can modify the stock bov to not break open at high boost,
once modified they will hold endless boost and cannot leak.
this is mainly due to the diaphram design of the stock bov being back pressurised by the manifold.

stace - when would you mod you BOV say like past 18 pound?

[QUOTE=tuna]you can modify the stock bov to not break open at high boost,
once modified they will hold endless boost and cannot leak.
this is mainly due to the diaphram design of the stock bov being back pressurised by the manifold.[/QUOTE]
Is there a "Tuna Tech" update on this? Would be a good mod. I have heard the Rally Guys have been doing this for years.

[QUOTE=UNDRGND]stace - when would you mod you BOV say like past 18 pound?[/QUOTE]

yeah, i'm holding over 30 pound now on the stock 99 bov.

morgs- yeah i'll pull mine out and grab some snaps shortly!

[QUOTE=SilentKilla]Its for wank factor, if anything the car will run worse when it goes "PSHH".[/QUOTE]

Logically speaking, the car running worse has nothing to do with the fitment of a atmospheric-style BOV... as other's have stated, it's your tuning!

I believe that BOV are a good safety precaution (turbo cavitation protection). It's very difficult to totally prove how they effect outright performance etc, but as long as it works effectively, any brand- even factory will do IMO.

I know there's the age old debate about using or not using one... happens over and over on other forums! The usual argument is:

"I've been running no BOV for years with my TD05 and it's fine"... however, as soon as you point out what can happen to say a VF22 (bent and broken impeller blades etc) the usual reply is"

"yeah, well you'd have to be stupid to run a VF22 without a BOV.. those turbos are a lot weaker!"

Here lies the irony of their statement, they seem to be missing the point... all things being equal, a turbo doesn't just fall apart because it's just simply a 'weaker design', it falls apart because there's some bloody huge backpressures acting on the weaker designed turbo! :laughing1
By admitting that some turbos cannot be run without a BOV only strengthens the overall argument of indeed using some form of pressure-bypassing device!! /rant off.

I've been using a gfb Stealth FX for a few years now. Great unit because they are designed well (acetyl piston rings etc), can be serviced locally- I get mine done approximately each year, are the largest diameter port in the range, and can run silent or vented to atmosphere. I generally run it closed, only opening for events as I find it gives 'audible feedback' as to where boost is etc at different throttle positions/ different corners etc.

tuna for the 99/00 BOV is that something similar like you can do on the nissans skyline BOV's? they have a small bleeder hole on the bov which you can block up i did it to my skyline and it held boost better.

[QUOTE=subarooboy]Logically speaking, the car running worse has nothing to do with the fitment of a atmospheric-style BOV... as other's have stated, it's your tuning!

I believe that BOV are a good safety precaution (turbo cavitation protection). It's very difficult to totally prove how they effect outright performance etc, but as long as it works effectively, any brand- even factory will do IMO.

I know there's the age old debate about using or not using one... happens over and over on other forums! The usual argument is:

"I've been running no BOV for years with my TD05 and it's fine"... however, as soon as you point out what can happen to say a VF22 (bent and broken impeller blades etc) the usual reply is"

"yeah, well you'd have to be stupid to run a VF22 without a BOV.. those turbos are a lot weaker!"

Here lies the irony of their statement, they seem to be missing the point... all things being equal, a turbo doesn't just fall apart because it's just simply a 'weaker design', it falls apart because there's some bloody huge backpressures acting on the weaker designed turbo! :laughing1
By admitting that some turbos cannot be run without a BOV only strengthens the overall argument of indeed using some form of pressure-bypassing device!! /rant off.

I've been using a gfb Stealth FX for a few years now. Great unit because they are designed well (acetyl piston rings etc), can be serviced locally- I get mine done approximately each year, are the largest diameter port in the range, and can run silent or vented to atmosphere. I generally run it closed, only opening for events as I find it gives 'audible feedback' as to where boost is etc at different throttle positions/ different corners etc.[/QUOTE]

True, but there are negative affects

[QUOTE]Are there any negative effects with aftermarket BOVs? Yes. The downside of releasing the air to atmosphere is that it has already been metered by the mass air sensor, and when it blows off, the ECU will be injecting the wrong amount of fuel into the cylinders. The engine temporarily runs extremely rich, meaning too much fuel is injected into the cylinders. [/QUOTE]

Use a modified stock BVP or an aftermarket BVP...
What is the function of a bypass valve (BPV)? To release pressure from the intake tract of a turbo car when the throttle closes. It is a vacuum-actuated valve designed to recirculate the air back into the intake before the turbo inlet, but after the airflow sensor.

There is no need to release to atmosphere, none at all