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Discussion Starter · #1 ·
i was wondering i got a 2003 vw gti 1.8t and i wanted to kno if i needed to get a bov kit for it. i kno itll help prolong the turbo's life, and i love the sound :). anyone kno if one comes stock, and if so can i change it to make the hiss sound?

if not can somone point me to a site were i could buy a decently priced one?

thanks again :D
 

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I just recently bought an 04 GTI 1.8T, and I've been wondering the same thing. I'm not sure if it has one or not, but every now & then I can hear a very, VERY faint sound that leads me to believe there may be one on it.... but I really don't know much about it, I'm new to Vdubs & turbos, so any help would be appreciated!
 

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Logixal said:
i was wondering i got a 2003 vw gti 1.8t and i wanted to kno if i needed to get a bov kit for it. i kno itll help prolong the turbo's life, and i love the sound :). anyone kno if one comes stock, and if so can i change it to make the hiss sound?

if not can somone point me to a site were i could buy a decently priced one?

thanks again :D
I think VW used diverter valves (not BOVs) in the 1.8T. If you go with an aftermarket BOV you run the risk of confusing the MAF and the ECU. Do a search on here for "diverter" and there are some good discussions on the differences.
 

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i heard a neuspeed CAI on a 1.8T and it definitly makes the diverter valve make a nice sound. check it out. neuspeed.com
 

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yeah the cold air intake sounds incredible, I actually just installed an AEM one yesterday on mine, and didn't hear much of a difference when I first cranked the car (I used to drive a honda, so that was the only time you really heard it!) & I was a little disappointed until I pulled outta the driveway & heard it. ;D
 

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From what I understand (and I'm no mechanic) if an engine comes stock with a bypass valve/diverter valve/etc and you install an aftermarket bov it will cause the engine to run rich as it is expecting more air that it is getting. I don't know exactly how the stock valve works on this car, but on an MR2 ;) it just recirculates the compressed air to the intake after the filter.

Also, are you sure you heard it was a bov that extends the life of the turbo? Sounds like a turbo timer to me...


-Arthur
 

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Discussion Starter · #9 ·
Ast0reth said:
From what I understand (and I'm no mechanic) if an engine comes stock with a bypass valve/diverter valve/etc and you install an aftermarket bov it will cause the engine to run rich as it is expecting more air that it is getting. I don't know exactly how the stock valve works on this car, but on an MR2 ;) it just recirculates the compressed air to the intake after the filter.

Also, are you sure you heard it was a bov that extends the life of the turbo? Sounds like a turbo timer to me...

-Arthur
Pressure release valve or more commonly known as a "Blow Off Valve", releases turbo pressure when the throttle plate is closed. The turbo is still spinning and still creating pressure. The forced air will hit the throttle plate and return where it came from. When a BOV reads vacuum from the manifold, it either opens a valve, or softens the valve. Which lets the pressure escape from it's opening. In order to work correctly the air must go back into the intake before your turbo because the Air Flow Meter has accounted for it. If not you will have a temporary rich condition which will upset your idle slightly.

was taken from

http://www.alltrac.net/tuning/bovfaq.html
 

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Yup. I knew that was the case with a 3SGTE, but I admittantly know nothing about the engine in my 1.8T. I don't even know what the engine code is!

As far as the sound goes, though, why not just take off the '1.8T' badge and go for the stealth approach? ;)
 

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I will try my best to break this down barney style for you so that everyone can understand (no offense to anyone)... stock 1.8T's come with a resurculating BOV, which means instead of running the air into the atmosphere it puts the air directly back into the intake AFTER the MAS (mass airflow sensor, *the thing that tells your ecu EXACTLY how much fuel to add*... it does that by telling you how much air is coming in the intake before the turbo)... so this is what happens, if you run a 1.8t atmospherically (the way you want to, with the "pshh" sound, which means instead of going into the intake it goes out into the open air) the ECU is thinking that the air in the intake just got put BACK into the intake (adding the fuel for it) and you just put that air into the atmosphere. basically if its using 3 parts air and 3 parts fuel, and you run an atmospheric BOV then your engine in now running 3 parts fuel and only 2 parts air, because it just let out the air that it thought it said it had... (make sense?)

NOW... there IS a way that you CAN run an ATMOSPHERIC BOV... WITHOUT running to rich...

you will however need either a new pipe to go from your intercooler to your intake manifold... because what you are going to do is take out where your MAS was factory ( look just to the right of the valve cover, on the intake pipe, its a solid plastic piece with a plug in it and a few wires, see it?) you are going to take out that solid piece of plastic, and (yes) cut the wires with enough room to re-soder(spelling?) them together, but you need to add a few feet of wire first, and instert that black piece of tubing that the sensor is housed in into the intercooler pipe leading to your intake manifold (closer= better)... what this intale does is create it so that you ecu is reading EXACTLY, NO IF ANDS OR BUTS ABOUT IT, how much air is going INTO your intake manifold. no matter what is happening before that... and there you go, any questions email me at [email protected], sorry this write up isnt so good, any questions feel free to ask!
 

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On the contrary, because of all the dubs *as well as other cars that need recirculation* looking into aftermarket BOV's, you can buy the recirculation kit for some *not all* BOV's. I used a Turbo XS racing BOV for a while, never changed how the car ran, it was a recirculating BOV tho.
 

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boostedJTi said:
it was a recirculating BOV tho.
Recirculating BOV? That's sorta an oxymoron. ;D

It technically can't be a BOV if it recirculates cold air. That would be a recirculating (or other wise known as a diverter) valve.
 

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I suppose it would be a valve, meh. I'm back to the stock one for now, whole sleeper thing kills ;)
 

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If they don't come stock with a BOV (which it is, diverter valve is just another name) then that whine you are hearing is the turbo spinning backwards from the air being slammed into the throttle plate and then forcing the turbo to reverse. That is VERY bad for the turbo. Get a nice bov, any recirculating bov will work. A bov WILL save the life of your turbo, as will a turbo timer.
 

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Trky said:
If they don't come stock with a BOV (which it is, diverter valve is just another name) then that whine you are hearing is the turbo spinning backwards from the air being slammed into the throttle plate and then forcing the turbo to reverse. That is VERY bad for the turbo. Get a nice bov, any recirculating bov will work. A bov WILL save the life of your turbo, as will a turbo timer.
Uhhhh... Let's try this again. A BOV causes excess air to be released to the atmosphere to protect the turbo (from compressor surge). A diverter valve or recirculating valve takes the same air and puts it back into the intake system to protect the turbo (from compressor surge). Surge is bad for your turbo.

If you use a BOV with a motor designed with a DV that has a MAF before the valve, you can and will cause confusion with the mass air flow sensor and the data it feeds to the ECU. This can cause check engine lights and cause the motor to run to rich, because the ECU is expecting a certain volume of air.

A turbo timer is NOT required on the 2.0 FSI (due to the nice VW engineers including a shutdown cooler), but it does not hurt to let it cool down if it was run hard or for long periods of time.

:)
 

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Dragon said:
Trky said:
If they don't come stock with a BOV (which it is, diverter valve is just another name) then that whine you are hearing is the turbo spinning backwards from the air being slammed into the throttle plate and then forcing the turbo to reverse. That is VERY bad for the turbo. Get a nice bov, any recirculating bov will work. A bov WILL save the life of your turbo, as will a turbo timer.
Uhhhh... Let's try this again. A BOV causes excess air to be released to the atmosphere to protect the turbo (from compressor surge). A diverter valve or recirculating valve takes the same air and puts it back into the intake system to protect the turbo (from compressor surge). Surge is bad for your turbo.

If you use a BOV with a motor designed with a DV that has a MAF before the valve, you can and will cause confusion with the mass air flow sensor and the data it feeds to the ECU. This can cause check engine lights and cause the motor to run to rich, because the ECU is expecting a certain volume of air.

A turbo timer is NOT required on the 2.0 FSI (due to the nice VW engineers including a shutdown cooler), but it does not hurt to let it cool down if it was run hard or for long periods of time.

:)
Uhh, not. A Blow off valve BLOWS OFF air from the throttle plate. Where it blows it does not matter. It can blowback into the intake which is recirculating, or blow into the atmosphere, which is what you are describing. I've worked on turbo cars all my driving life. I know a thing or two.
 

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Also a turbo timer is recommended if you have a turbo car no matter what company designed it. If you shut the car off before the turbo has had time to cool down the oil will boil and destroy the oil which causes it to cake on the turbine and over time this is harmful to the motor. A turbo timer lets the motor run for a little bit after the key is turned off which keeps the oil flowing through the turbo. 60 seconds to three minutes is usually a long enough time for any turbo car.
 
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