# TT BLOW-OFF VALVES



## Kabir (Nov 30, 2004)

what is a good bov for the TT that wont run rich or mess up the CPU
.........not a dv, a BOV?
any suggestions?
thanks


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## Kabir (Nov 30, 2004)

*Re: TT BLOW-OFF VALVES (Kabir)*


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## sharons03jetta (Jul 6, 2005)

non that I have ever heard of.....just get a CAI and live witht the sound that it provides....the 1.8t with a CAI sounds pretty good with stock DV


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## SpongeTheOc (Aug 14, 2006)

*Re: (sharons03jetta)*

get the intake done, then the forge 007DV valve..plenty loud for me, and im deaf..i used to have an 02'SI with a greddy turbo kit with a loud turbo XS bov...and i like the dv valve, much better sounding, remember, ur driving a euro!!! http://****************.com/smile/emthup.gif


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## cincyTT (May 11, 2006)

*Re: (SpongeTheOc)*

hks ssqv now go nuts


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## formulanerd (Feb 19, 2005)

im' running the hks ssqv, works fine for me, but i'm not running a stock setup. hell i dont even have a MAF. lol











_Modified by formulanerd at 11:16 AM 10-27-2006_


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## idwurks (Oct 25, 2003)

*Re: (formulanerd)*

If you get a Forge 007 or a different DIVERTER VALVE, it will still make that sound. Please dont run a BOV on your recirculating air system http://****************.com/smile/emthdown.gif


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## Kabir (Nov 30, 2004)

*Re: (idwurks)*

but.. will the DV make the WHOSS sound/
or which valve can i use to make that sounds.. i mean using one for the recirculating air system.


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## eastcoastdubs (Feb 5, 2001)

*Re: (Kabir)*

baileys dv, vtda modshack cai, lower raintray compartment molding = lovely sound. Honestly, normal driving you hear a nice whoosh. When your pushing it it sounds just like a BOV. works fine.


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## Kabir (Nov 30, 2004)

*Re: (eastcoastdubs)*

cool.. i got you.. so its similar as a atmosphere bov, i mean not as much but quite similar.
is there a link to where i can get this...
thanx


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## idwurks (Oct 25, 2003)

*Re: (Kabir)*

http://setuning.com/ecom/produ...d/110








Forge 007 adjustable. The only main difference between a BOV and a DV is that instead of venting to the atmosphere, a DV recirculates the boost back into the intake manifold. They make almost the same sound.


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## Kabir (Nov 30, 2004)

*Re: (idwurks)*

i used to have that forge 007 dv but it din't make any noice just a small psshh that you only hear it if u paid attention..
whats about this one the TURBO XS valve? familiar with this one.. 
does it make a loud whooosh?


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## idwurks (Oct 25, 2003)

*Re: (Kabir)*

If you have an intake, any of them make a sound. Did you have an intake? I doubt it.
Nobody in this forum is going to know what has a "loud whoosh." Why dont you go into the Mk4 forum and ask them.


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## InTTruder (Mar 28, 2006)

IMO, a BOV means lost energy as the BOV resets at a lower pressure. This means the turbo spools down some, and you have some lag as you attempt to exit the corner, or re-accelerate.
Unless you change a lot more on the ECM and plumbing, a waste.


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## 1.8Tabamoura (Jul 29, 2005)

*Re: (InTTruder)*


_Quote, originally posted by *InTTruder* »_IMO, a BOV means lost energy as the BOV resets at a lower pressure. This means the turbo spools down some, and you have some lag as you attempt to exit the corner, or re-accelerate.
Unless you change a lot more on the ECM and plumbing, a waste.

the BOV releasing to the atmosphere is actually better to keep the turbine spinning freely ,if the turbine is fast enough the pressure will be back up faster ( less lag) , If the pressure is kept high when the throttle body closes the turbine would stall from the back pressure.
the DV makes the air circulate in a loop , kind of a mid term.
I have an hybrid adjustable BOV/DV that can be adjusted from full bov ( going through hybrid to full DV ) and I can make a video of the boost guage showing wich one would bring the boost back faster if you want.
the problem is that the MAF reads the airflow before the turbo and if the BOV releases the air , the ECU will add too much fuel ( causing a too rich condition) thininking that the air is till there when it got released . A perfect solution would be moving the MAF to "after the valve " but I don't know what other consequenses that would have .




_Modified by 1.8Tabamoura at 10:25 AM 10-29-2006_


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## 1.8Tabamoura (Jul 29, 2005)

*Re: (idwurks)*


_Quote, originally posted by *idwurks* »_If you have an intake, any of them make a sound. Did you have an intake? I doubt it.
Nobody in this forum is going to know what has a "loud whoosh." Why dont you go into the Mk4 forum and ask them. 

BOV's have a trumpet no DV with an intake will be louder than a BOV, if the guy wants to hear the sound of the BOV whats the big deal ? Why do you have to be rude to him .


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## InTTruder (Mar 28, 2006)

Some 'relief valve theory':
Without backpressure (BOV to atmosphere), the turbo spools way up on los of b/p. But the sensor package senses a drop in the system: The ECU/EMS senses a drop in pressure, and behaves accordingly.
The ECM may be 'integral/derivative', i.e.: it senses the changes and changes response based on rate, but the BOV is a lousy way to run the EMS. The EMS is looking at changes in charge pressure, and IIRC the BOV will cause a more rapid drop in charge pressure, ergo, the EMS will want to lean back out.
Been a LONG time since I did valve design, but the electronics guys are way ahead of me here.
I'll go look at the plumbing diagram and see where I'm making an error/miscalculation.


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## cincyTT (May 11, 2006)

*Re: (1.8Tabamoura)*


_Quote, originally posted by *1.8Tabamoura* »_
A perfect solution would be moving the MAF to "after the valve " but I don't know what other consequenses that would have .
_Modified by 1.8Tabamoura at 10:25 AM 10-29-2006_

Ive run that way with my 02 turbo lancer. ran fine with it after the bov but with it (7psi) with the maf before the bov it would stall in between shifts. The only problem is that it is harder to meter the air that has been pressurized and it can harm the maf. But then again their is someone who has been running it like that for a few years know with no ill effects.


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## Kabir (Nov 30, 2004)

*Re: (cincyTT)*

nope. i dont have an intake. which one do you recommend that will give me the similar woosh.. to the bov..
so basically a bov makes the car rush rich and waste more gas??


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## TheTiTTy (Oct 4, 2006)

Im trying to sell my HKS SSQV. it sounds pretty good but i got a forge DV now.


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## 1.8Tabamoura (Jul 29, 2005)

*Re: (Kabir)*

you won't probably see the difference on gas , but basically yes, I recomend a adjustable one , so you can have the BOV noise only when you wanted , this is the link for the valve , they are hard to come by but they pop on ebay once in a while, I had one of these on my 1.8T Passat and it worked very well .
http://www.gofastbits.com/inde...=1008
http://cgi.ebay.com/ebaymotors...wItem



_Modified by 1.8Tabamoura at 5:56 PM 10-31-2006_


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## idwurks (Oct 25, 2003)

*Re: (1.8Tabamoura)*


_Quote, originally posted by *1.8Tabamoura* »_BOV's have a trumpet no DV with an intake will be louder than a BOV, if the guy wants to hear the sound of the BOV whats the big deal ? Why do you have to be rude to him . 

No one is stopping him from buying what he wants. It is just common knowledge that our cars do not run properly on BOVs without modifications - wasting fuel and not helping the car perform at its best.
I have heard very loud DV's before. Some people reverse them and run them upside down - that could be helpful to get more sound.


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## InTTruder (Mar 28, 2006)

*Re: TT BLOW-OFF VALVES (Kabir)*









Look at the plumbing. The ECU is sensing pressure downstream of the SMIC and throttle butterfly. The DV receives no control signal from anything, merely senses pressure in the intake pipe. It gets feedback from a recirc valve, no more. Dumping it for a BOV would be wasting intake charge IMO. 
Replacing the Wastegate means some ECU/EMS adjustments, since the N75 is driving the gate. So, in the FWIW department (w/o dyno) changing your DV out for a BOV would be a 'waste', and cause your ECU/EMS some confusion unless you are writing code. 
In that case, join APR.


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