Starfighterpilot Posted September 29, 2015 Report Share Posted September 29, 2015 Like the Post title says, what good is a blow off valve - unless you are running a non OEM Starquest with an over sized turbo on highly modified G54B T engine to support it, what good are they? It has always seemed to me that when running a factory stock 12A or 14B turbo & FI setup they are more trouble than they are worth. BTW - I like the turbo turkey gobble and it has not degraded any of the 3 turbos that I've had on the Old Broad. They failed cuz of worn out oil seals. Feel free to chime in. For What It's Worth. KEN Link to comment Share on other sites More sharing options...
speedyquest Posted September 29, 2015 Report Share Posted September 29, 2015 (edited) Heya Ken. That is not bad question and I think you already know your going to get a wide spectrum of answers on this but here is my personal take on the subject. Firstly I will say I'm no expert so anything I say take with a grain of salt because compared to others here I'm rather low on the "knowledge totem pole". From everything I've read and seen a blow off valve has a few benefits over not running one. The first one most people will talk about is stopping compressor surge. That I think is what your talking about when you say your turbo "gobbles". Basically when you let off the gas exhaust isn't continuing to exert as much pressure on your turbos hotside. While that happens there is still pressure built up in your intercooler piping and isn't entering the motor because the throttle body is closed. This can in some cases cause the compressor wheel to get resistance or even possibly spin backwards which isn't good for the turbo. A blow off valve releases that pressure and stops that pressure exerting force back on the compressor wheel. The downside to running a bov on a stock starion however is that because it is a pull through setup you are releasing metered air out of the intake track. This causes a rich condition when you let off the gas. Some guys just ignore it and accept it. The ones that do try and do something about it recirculate that released metered air back into the intake track before the turbo. At the end of the day though Ken you've had your car longer than most of us and since you've not had a bov this whole time I can't see how anyone could argue that you NEED one. Its nice and all but required? I don't think so. Edited September 29, 2015 by speedyquest Link to comment Share on other sites More sharing options...
button Posted September 29, 2015 Report Share Posted September 29, 2015 If you are running low boost, you probably won't bend a compressor blade.But a blow off valve, or diverter valve, allows the air that has already been compressed to escape when the throttle is snapped shut so that the turbo doesn't stall or attempt to spin backwards for that brief millisecond.Saving your turbo and increasing turbo response when you shift in a manual. Auto guys put them on because they sound cool. jk about the auto thing, on an auto it can save the turbo as well after a full pass, so it has less chance to break the turbo. Link to comment Share on other sites More sharing options...
Starfighterpilot Posted September 29, 2015 Author Report Share Posted September 29, 2015 Let me say this, In my drag racing days when the Old Broad was a baby circa 88 - 92 when I got involved in "competive exhibitions of speed" (cop term for street racing back then); or when drag racing my Charger on the street,1960's to late '80's, I never let off of the throttle while "tapping" the clutch during shifting between gears. Never broke anything doing that except for going through a number of clutches. For What It's Worth KEN Link to comment Share on other sites More sharing options...
IntercooledFlatty Posted September 29, 2015 Report Share Posted September 29, 2015 vrrrooooommmmmmm.....psssshhhhhhhhhhttt Link to comment Share on other sites More sharing options...
87redcat Posted September 29, 2015 Report Share Posted September 29, 2015 ^^^ dude ^^^ eliminates compressor stall. basically keeps the turbo spinning.that turkey gobble is compressor stall. Like some of the other guys said at higher boost one is needed.Mitsubishi didnt put one on these cars cause they figured they didnt need it. Link to comment Share on other sites More sharing options...
JohnnyWadd Posted September 29, 2015 Report Share Posted September 29, 2015 It gives you street cred Link to comment Share on other sites More sharing options...
JohnnyWadd Posted September 29, 2015 Report Share Posted September 29, 2015 BTW - I like the turbo turkey gobble and it has not degraded any of the 3 turbos that I've had on the Old Broad. They failed cuz of worn out oil seals. KEN The shock motion on the seals cannot be good on them. Having a compressor bypass take shock off the whole turbo assembly , not just the wheel. Shutting the throttle with pressure in the piping means anything that can give will. So the thrust load on the compressor wheel is also going to increase. Link to comment Share on other sites More sharing options...
importwarrior Posted September 29, 2015 Report Share Posted September 29, 2015 Link to comment Share on other sites More sharing options...
BOHO Posted September 29, 2015 Report Share Posted September 29, 2015 I like my turboxs type H. It just sounds like a rush of air. No whistle, no squeak, no bark...Its really the only sound I like on the old bov. Link to comment Share on other sites More sharing options...
importwarrior Posted September 29, 2015 Report Share Posted September 29, 2015 I have this one and really like the sound. http://www.alamomotorsports.com/turboxs/turboxs_bov_h.jpg Link to comment Share on other sites More sharing options...
87redcat Posted September 30, 2015 Report Share Posted September 30, 2015 that's the one I have ^^^ great sound Link to comment Share on other sites More sharing options...
Starfighterpilot Posted September 30, 2015 Author Report Share Posted September 30, 2015 The shock motion on the seals cannot be good on them. Having a compressor bypass take shock off the whole turbo assembly , not just the wheel. Shutting the throttle with pressure in the piping means anything that can give will. So the thrust load on the compressor wheel is also going to increase. For manual trannys only - I give credence to what you are saying above if you completely, or partially, take you foot off of the accelerator pedal when tapping the clutch and shifting to the next higher gear. However, I never took my foot off of the "floored" position on the accelerater pedal and "dumped" the clutch in 88 - 92 when she was a baby. WHY? Cuz of what you are talking about and I didn't want any potential turbo lag getting it back up to RPM (boost). Ya just got to know how to shift W/O loosing the engine RPM, HP & torque that you have already generated in the gear that you have shifted from. BTW - I didn't have the Old Broad's factory OEM 12A turbo rebuilt because of a weeping oil seal until, according to my maintance records, 176,566 miles. That was when I would ocassionally turn up the boost to 12 PSIG when my ex-wife and I would go out on the streets "stalking." I think the oil seal was just plain worn out cuz of the mileage on it. I appreciate your input and everyone else that's responded tho. For What It's Worth. KEN Link to comment Share on other sites More sharing options...
JohnnyWadd Posted September 30, 2015 Report Share Posted September 30, 2015 (edited) For manual trannys only - I give credence to what you are saying above if you completely,KEN For any transmission. You cannot tell me you are going to drive in such a manner that your foot action will do the work of a blow off valve. Perhaps sometimes. But skilled driving is not about keeping the throttle pegged and quick shifting and dumping the clutch just to prevent compressor stall. You say you are keeping it floored and banging gears? Ok that's fine. But you also said you where getting turkey gobble, so having a blow off valve would have prolonged turbo life. Really over engineering this whole thing. It's just a simple compressor bypass valve. It sees manifold and charge line pressure and manages it. Saves stress on the turbo manual or automatic. Sometimes you are going to loose traction when you drive like you mentioned flooring it and dumping the clutch. Better of with a proper valve on there. Edited September 30, 2015 by JohnnyWadd Link to comment Share on other sites More sharing options...
pure_insanity Posted September 30, 2015 Report Share Posted September 30, 2015 Hey Ken. Haven't heard from you in a good long while. We need to get together soon. Link to comment Share on other sites More sharing options...
IntercooledFlatty Posted September 30, 2015 Report Share Posted September 30, 2015 For manual trannys only bruce jenner ? Link to comment Share on other sites More sharing options...
88351wtsi Posted September 30, 2015 Report Share Posted September 30, 2015 omg lol I almost cried I laughed so hard Link to comment Share on other sites More sharing options...
JohnnyWadd Posted October 1, 2015 Report Share Posted October 1, 2015 http://memeshare.net/memes/5/4916.pngFor manual trannys only bruce jenner ? Link to comment Share on other sites More sharing options...
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