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Re: blow off valve (dhellz)

From what I have found on here they are pretty much a no no.....just run an open style air filter, and you'll hear the stock re-circ valve enough to know it's there.
 

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Re: blow off valve (dhellz)

Search is your friend. If I remember correctly, the R setup is not friendly to a BOV but if you like the noise (and a r$cey R), go for it.
 

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Re: blow off valve (MagoonR)

OuR system holds the boost at higher revs so the next gear has less lag. A BOV will let the much needed pressure out (rather than hold most of it in) and then the turbo has some lag trying to build that boost again for the next gear. I hope this helps, Rick
 

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Discussion Starter · #5 ·
thanx it helped alot. i would never do somthing which would in any way take away fromt he car. i appreciate the imput.
 

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Re: blow off valve (Mash)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Mash</b> »</i></TD></TR><TR><TD CLASS="quote">OuR system holds the boost at higher revs so the next gear has less lag. A BOV will let the much needed pressure out (rather than hold most of it in) and then the turbo has some lag trying to build that boost again for the next gear. I hope this helps, Rick</TD></TR></TABLE><p>I think you are missing the BOV or CBV concept here..<p>The R already has a bypass valve which vents back to the intake. The reason it is thre is to avoid back pressure on the compressor when the throttle plate closes. This back pressure normally will act like a brake on the compressor wheel. By venting the pressure in the channel the wheel keeps spinning and the moment the throttle is back on the turbo hould deliver boost immediately.<br>In other words, a BOV prevents lag.<p>The reason why a BOV isn't such a good mod for the R is because the R, as many other cars, uses an air meter to monitor/measure how much air is going in to the egine. With a BOV this measured air is vented to atmosphere and fuel was provided for it in the process which will result in a rich condition after shifting or releasing throttle.<p>If you want to use a BOV go look for the adjustable type. The non adjustable ones are not very suitable for a Volvo and might cause the engine to stall on throttle release.<p>A totally useless mods if you ask me unless you want to have the Wooosh at all cost.<p>
 

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Re: blow off valve (Johann)

I have the BMC filter and R Kelly's CAI. I pretty much hear "woosh" any time the turbo is kicking in. Not obnoxious, but you (from outside the car) can definately tell it is a turbo car.<p>Not sure if this is exactly what you are looking for with a BOV, but this is how you get "woosh".<p>I think you can get the BMC from ViVaPerformance and just do a search for the R Kelly CAI. I'm not sure he is making anymore, but you should be able to figure out the parts. JLemly also made one using a $10 PVC pipe from Lowes that probably works about the same.<p>Search is your friend on these subjects.<br>-Ben
 

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Re: blow off valve (Johann)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Johann</b> »</i></TD></TR><TR><TD CLASS="quote">A totally useless mods if you ask me unless you want to have the Wooosh at all cost.</TD></TR></TABLE><br>Actually, I would go further and call it a harmful mod.<p>Bcantana, whoosh on acceleration is different from BOV whoosh. BOVs vent air when you back off, and loudly.<p>Tom.
 

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Re: blow off valve (tmtalpey)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>tmtalpey</b> »</i></TD></TR><TR><TD CLASS="quote"><br>Bcantana, whoosh on acceleration is different from BOV whoosh. BOVs vent air when you back off, and loudly.</TD></TR></TABLE><p>Thanks for the clarification. I'll have to rent "The Fast and the Furious" to see what you are talking about!<p> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0"> <p>-Ben
 

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Re: blow off valve (Johann)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Johann</b> »</i></TD></TR><TR><TD CLASS="quote">The reason why a BOV isn't such a good mod for the R is because the R, as many other cars, uses an air meter to monitor/measure how much air is going in to the egine. With a BOV this measured air is vented to atmosphere and fuel was provided for it in the process which will result in a rich condition after shifting or releasing throttle.<p>A totally useless mods if you ask me unless you want to have the Wooosh at all cost.</TD></TR></TABLE><p>This has been long debated in turbo communities. All OEM turbos have bypass valve that vents back to intake, and they all have AFM that measures airflow. However, the debate comes from where the air is vented back. In OEM application, air is vented back <B>AFTER</B> the AFM. The idea is that the air had already been measured, so it should not be measured again. This extra air going back to intake actually causes a lean situation since AFM isn't adding extra fuel to compensate air vented back. <br>This really becomes a problem for high HP cars as their A/F ratio is already critically lean to achieve best performance mixture (all OEM cars run on rich side for emmission reasons). This extra shot of air could easily push A/F ratio pass the safe limit and cause piston meltdown, therefore, a BOV is used to vent the air out of the system. <p>So, BOV in the right application is not a totally useless mod. It's actually a critical one. However, too many people do it for the whooosh rather than it's really effect, and install them in useless applications.
 

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Re: blow off valve (mister2cool)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>mister2cool</b> »</i></TD></TR><TR><TD CLASS="quote">This extra air going back to intake actually causes a lean situation since AFM isn't adding extra fuel to compensate air vented back.</TD></TR></TABLE><br>I agree there is much to debate, but what "extra" air? This is only pressure, there is no additional air entering the system, nor is any entering air bypassing the MAF. The already-metered air is simply going round and round waiting for the throttle to open.<p>Tom.
 

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Re: blow off valve (tmtalpey)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>tmtalpey</b> »</i></TD></TR><TR><TD CLASS="quote">I agree there is much to debate, but what "extra" air? This is only pressure, there is no additional air entering the system, nor is any entering air bypassing the MAF. The already-metered air is simply going round and round waiting for the throttle to open.<p>Tom.</TD></TR></TABLE><p><IMG NAME="icon" SRC="http://www.vwvortex.com/zeroforum_graphics/screwy.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/zeroforum_graphics/screwy.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/zeroforum_graphics/screwy.gif" BORDER="0"> <p>By extra, I meant air that had already been metered by AFM but did not enter throttle. As you close throttle, some metered and pressurized air gets trapped. When throttle opens again, the trapped air goes into cyclinder and AFM doesn't know it is pressurized air going in, and you get your lean condition.
 

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Re: blow off valve (mister2cool)

Ok, I understand your point. No need for screwies.<p>Thanks.<p>Tom.
 

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Re: blow off valve (tmtalpey)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>tmtalpey</b> »</i></TD></TR><TR><TD CLASS="quote">Ok, I understand your point. No need for screwies.<p>Thanks.<p>Tom.</TD></TR></TABLE><p>LOL, sorry, didn't mean to being sarcastic. Your really got me scratching my head for a moment, because you were right about no additional air was introduced into the system. I was like.. hmm.... what's wrong with this picture?
 

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Re: blow off valve (mister2cool)

I like that! "No more screwies" <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0">
 

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Re: blow off valve (tmtalpey)

the BOV is so lame. every time i see some ricer car on teh road and I hear that loud "whoosh" sound - i think - it sort of sounds cool the FIRST time you hear it.<p>but when you stop and think that the car will make that WHOOOSH sound EVERY stinking time you shift under boost.....forget it... i think you would lose your mind...<p>WHOOSH WHOSH WHOOSH WHOOSH.... WHOOSH WHOOOSH .... WHOOSH WHOOOSH... <p>the factory compressor bypass thingy is loud enough to hear, but it's very subtle....that's about was "whooshy" as I want... <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/tongue.gif" BORDER="0">
 

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Re: blow off valve (mister2cool)

So, I want to add that I hate BOVs, I think they're obnoxious and a quick and dirty fix to a very subtle problem. If there are two things Volvo knows how to do well, it's turbos and station wagons. Prying well-engineered engine plumbing open to stick in a fart valve is what I think is <IMG NAME="icon" SRC="http://www.vwvortex.com/zeroforum_graphics/screwy.gif" BORDER="0"> <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <p>Okay that said, I think if the CBV causes a lean condition due to holding onto air before the throttle plate, it's <U>very </U>brief and happens at a relatively harmless point in the engine load (while backing off).<p>For sure however, a BOV will chuck out a slug of turbo'd air, which will excite the MAF and tell the ECM to dump a matching slug of fuel. Personally, I don't think that will help the rings or the emissions logic at all, and it will happen every shift. In addition to all that farting noise.<p>This is however only my opinion, and is untested by real measurement. Not that I want to try! <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0"> <p>Tom.
 

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Re: blow off valve (tmtalpey)

With the mods that I have the whoooosh has turned to a high pitched CHIRP, then whooosh, then BANG. When the car is under extreme pull and at high revs, I can get it to do every time. However when I am subtle with the gas pedal (which is hard to do because of the "new noises") it sounds a little louder than stock. My 9 month old can still sleep undesturbed. Thank goodness for the "subtle" sound at low revs. My wife would kill me if she heard this car under full pull. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/eek.gif" BORDER="0"> I know the big contributer to hearing alot of these new noises is the addition of the Evolve hood vent right above my oai.<BR><BR>
<i>Modified by Mash at 4:44 PM 6-7-2006</i>
 
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