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Discussion Starter · #1 ·
Hi all,<br>I just bought a beautiful 1999 C70 convertible, and of course immediately wanted it to go faster. I have been reading all of the posts here and at other volvo forums and have learned quite a lot. But i do have a few questions. what is a blow off valve? how does it help? will it work/is it needed, on an automatic? (I know, I know but C70 Conv's with Manual Xmssions are as rare as hens teeth) anyway, where can I get one? What are the other must haves for the 2.4 LPT? I have or will be soon adding a K&N filter, IPD sway bars, ECU upgrade, Catback upgrade, strut tower brace, platinum plugs, and upgraded plug wires. did I miss anything? any particular manufacturers ( I really only know of IPD and Eastern Aerospace) I have heard some bad comments about them in this forum and others, does anyone have anything good to say about them? I am very interested in the turbo upgrade they offer on thier website. has anyone had this done? Results? Thanks<br>Mike in MD
 

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Re: blow off valve ?'s (mldolan)

A blow off valve, aka 'dump valve', is used to limit Turbo stall. <p>Between changes and every time you lif off the gas, the turbo continues to spin & builds up pressure, which effectively has nowhere to go. As a result, this is then forced backwards through the compressor housing stalling the turbo.<p>A blow off valve lets this escape (hence the hiss) keeping the turbo spinning and effectively reducing lag when you put you foot down again.<p>In some cases, I've heard that the backpressure from cars with real high boost is enough to cause cracking on the turbo casing, but how true this is, I don't know. <IMG NAME="icon" SRC="http://********************/smile/emcrook.gif" BORDER="0"> <p>Anyway they will work on your auto and in fact, your car does already have one bolted directly to the turbo (I think is of the recirculating type so you cant hear it.) <IMG NAME="icon" SRC="http://********************/smile/emsad.gif" BORDER="0"> <p>If you do go for one, remember to buy the blanking plate for the original or you will end up loosing boost. Also, go for the piston varity instead of a diaphram (as I've found these these split/leak easily).<p>
 

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Re: blow off valve ?'s (mldolan)

Hey, Mike...congrat on the purchase. Man...a convertible at this time of year in MD. <IMG NAME="icon" SRC="http://********************/smile/emwink.gif" BORDER="0"> We got bunch of MD people on Swedespeed and we have GTG events every once awhile, you should consider coming out to meet with us if you have a chance.<br>I'd be glad to share some notes with you on my experience with my C70. Hehe...finally we got another C70 in this crowd. <IMG NAME="icon" SRC="http://********************/smile/emsmile.gif" BORDER="0"> I'm in Rockville area, feel free to drop by. IPD is good, probably the most reputable and dependable company in the Volvo market, but at the same time...they are almost as conservative as Volvo. EA is just full of it, don't even want to go into details, maybe let you in more details later.<br>Email me offline and let me know what you plan to do, I'll try my best to give you some pointers....but could be limited since I'm not too familiar with the LPT model.<br>Good luck.
 

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Re: blow off valve ?'s (The_one_n_only)

Hey, I got some topless time in yesterday, so it is all worth it. great heaters in those C70s. I guess I'll cross the plug wires off of my list as my car dosen't appear to have any. BTW where do they hide the spark plugs in these cars? or did the 99 models do away with those as well. <IMG NAME="icon" SRC="http://********************/smile/emsmile.gif" BORDER="0"> , thanks for the advice on eastern those numbers sounded too good to be true.
 

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Re: blow off valve ?'s (mldolan)

From Volvospy. <p><A HREF="http://vvspy.com/resources/photoalbum/show.php?id=2837&type" TARGET="_blank">http://vvspy.com/resources/photoalbum/show.php?id=2837&type</a>=<br><A HREF="http://vvspy.com/resources/photoalbum/show.php?id=2838&type" TARGET="_blank">http://vvspy.com/resources/photoalbum/show.php?id=2838&type</a>=<br><A HREF="http://vvspy.com/resources/photoalbum/show.php?id=2839&type" TARGET="_blank">http://vvspy.com/resources/photoalbum/show.php?id=2839&type</a>=
 

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Re: blow off valve ?'s (The_one_n_only)

Since its the recirculating type, is there anyway we can make the excess pressure shoot off into the atmoshphere instead of back into the intake or wherever somehow? I know lots of you don't like the noise, but I'm a younger guy and think its a neat sound. Is there just a hose or somthing that recirculates it?
 

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Re: blow off valve ?'s (Faraaz23)

Yes, there is a hose coming off the recirc valve that goes back into the intake. I am not sure if this would produce the desired sound tho, and it may cause the car to run slightly rich and times from what i understand.
 

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Re: blow off valve ?'s (Faraaz23)

Yes, you can always just make it vent the air into the atmosphere. There is no guarantee if that will trigger a check engine light on you or now; especially on the newer models with different ECM.<p>Some block off the original recirc valve (Johann did it w/ his s60 once), some leave the original recirc valve in place. I'd still block that off in case it still gets forced open at higher boost. Maybe Johann can jump in on this one.<p>You will get the desire noise, just not going to be too loud since the low boost you have now. Some even said it would be louder if you have the BOV mounted btwn the TB and IC...and supposedly more responsive? <p>I have BOV b/c the new turbo doesn't come with a bypass valve built in...and I have it let off into the air b/c I'm just too lazy to reroute it. <IMG NAME="icon" SRC="http://********************/smile/emsmilep.gif" BORDER="0"> Plus, don't have check engine light triggered by that yet. My car always runs a bit richer than the other the other T5s, so running rich is never a concern to me.
 

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Re: blow off valve ?'s (Kai)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>Kai</b> »</i></TD></TR><TR><TD CLASS="quote">Some even said it would be louder if you have the BOV mounted btwn the TB and IC...and supposedly more responsive? <br></TD></TR></TABLE><p>Actually, the loudest spot for a BOV would be as close to the turbo as possible, however this is not the best for response, as the compressed air must travel through the IC and piping again after you get back on the throttle. The quickest boost response is by mounting the BOV as close to the TB as possible. <p>I would be interested in mounting a high quality BOV such as an HKS or Tial unit as I simply like the sound. It will be strictly aesthetic on my automatic car, but the sound is just so awesome. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> . But as I understand, it would cause some complications on this car.<p>Has anyone (other than Kai...someone on a stock or 19T turbo) mounted a BOV on a T5? What was your experience like?
 

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Re: blow off valve ?'s (HPTJoe)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD><i>Quote, originally posted by <b>HPTJoe</b> »</i></TD></TR><TR><TD CLASS="quote"><br>Actually, the loudest spot for a BOV would be as close to the turbo as possible</TD></TR></TABLE><br>That's what I thought, but on my C, I don't think it's all that loud....even w/ Blitz one. Maybe I need to bring it even closer to the turbo. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/tongue.gif" BORDER="0">
 

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Re: blow off valve ?'s (Kai)

I think your BOV is ok loud for a Blitz. The HKS on the other hand is mega loud. The other night I was doing a drive with my friends. I was following a friend with a F355 in the twisties, and I had to let off the gas quite often because he was too slow <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> . My HKS BOV was so loud that he thought his car was having problems and the sound was coming outta his car <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/eek.gif" BORDER="0"> (he was like "I thought my car was having problems, I could hear the sound when I was shifting, braking, blah blah blah..." Those Ferrari drivers <IMG NAME="icon" SRC="http://www.vwvortex.com/zeroforum_graphics/screwy.gif" BORDER="0"> ) And even the Porsche in front of the F355 could hear my BOV venting. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/biggrin.gif" BORDER="0"> <p>By the way, I need to get a ride in your R if I come to the states again <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/tongue.gif" BORDER="0">
 

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Re: blow off valve ?'s (Terence)

Yeah...you need to come back to the States again!! Hopefully not for the exam, though. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/wink.gif" BORDER="0"><p>I think since the HKS one has more of that bird chirp noise, it's probably easier to hear. <IMG NAME="icon" SRC="http://www.vwvortex.com/vwbb/tongue.gif" BORDER="0"> If only I can stand that type of BOV sound....<p>I've actually heard the Blitz BOV on last gen Eclipse once, and for some reason it was a lot louder.
 
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