blow off valves instead of bypass valves?
09-02-2004, 11:48 AM
#2
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I seem to remember a post about this, recently.
If I remember right it turned into a rant about how blowoff valves are for ricer kids who want it only for the noise, and that they should sell their A6 and get a civic. hehehe.
On a serious note, IIRC the post said that the system is designed for bypass valves and blow-off valves aren't really feasible. Try searching though, I could be wrong.
On a serious note, IIRC the post said that the system is designed for bypass valves and blow-off valves aren't really feasible. Try searching though, I could be wrong.
09-02-2004, 11:51 AM
#3
Please search. Covered in great detail
Basically because you vent metered air, the car cannot properly adjust the air/fuel ratio. You risk engine damage over the long term. BOVs can be made to work on VAG cars, but unless properly modified and used in cars with a high state of tune, there is no reason to do so. If you want the noise, get of those BOV noisemakers that are hooked up to your tach and make the sound whenever you let off the gas;-)
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09-02-2004, 02:16 PM
#10
Yes it is possible. (long)
I don't think they are only for ricer kids. I had an aftermarket one in my previous turbo car and it could hold 21psi without a problem. I tested my stock plastic one to hold 11psi before the stock spring would let the valve open under full boost.
There is definitely a reason for their existence. Even my stock bov which was cheap plastic would make the "pitssshh" sound, there is no way around it when you're venting off pressurized air. I don't think many car companies would spend the money to design an internal baffle or muffler to mute this sound.
My friend had one on his Golf GTI. I know a few A4 owners with them too.
Both stock and aftermarket valves do essentially the same thing. My car blew off metered air too, and would stall unless a tube from the BOV outlet was dumped back into the intake stream. This wasnt a problem as the stock setup was designed like this as well. You could and should do the same if you wish to do an install like this. But you need to understand the point of having one. It's too have a stronger spring to be able to hold higher pressures, not for sound.
If you were to do the conversion you basically need an adapter flange from the stock bypass valve location to the fitting on the aftermarket blow off valve. Then you would need to connect the vacuum lines onto the aftermarket valve, and adjust the spring to the desired rate via a screw on the aftermarket unit. A spring that is set too tight might not correctly discharge the air, and cause damage to the turbo. Too loose and you will have precious boost pressure escaping. They're very easy to adapt and install.
You may need two blow off valves to properly discharge the pressure from both turbo's. I am curious to study the design of the stock bypass valves on the turbo audi's. A lot of people seem to think blow off valves are not a proper fitment, so perhaps there is some logic to this.
Please note, a blow off valve is actually, more properly called a compressor bypass valve. Same name?
There is definitely a reason for their existence. Even my stock bov which was cheap plastic would make the "pitssshh" sound, there is no way around it when you're venting off pressurized air. I don't think many car companies would spend the money to design an internal baffle or muffler to mute this sound.
My friend had one on his Golf GTI. I know a few A4 owners with them too.
Both stock and aftermarket valves do essentially the same thing. My car blew off metered air too, and would stall unless a tube from the BOV outlet was dumped back into the intake stream. This wasnt a problem as the stock setup was designed like this as well. You could and should do the same if you wish to do an install like this. But you need to understand the point of having one. It's too have a stronger spring to be able to hold higher pressures, not for sound.
If you were to do the conversion you basically need an adapter flange from the stock bypass valve location to the fitting on the aftermarket blow off valve. Then you would need to connect the vacuum lines onto the aftermarket valve, and adjust the spring to the desired rate via a screw on the aftermarket unit. A spring that is set too tight might not correctly discharge the air, and cause damage to the turbo. Too loose and you will have precious boost pressure escaping. They're very easy to adapt and install.
You may need two blow off valves to properly discharge the pressure from both turbo's. I am curious to study the design of the stock bypass valves on the turbo audi's. A lot of people seem to think blow off valves are not a proper fitment, so perhaps there is some logic to this.
Please note, a blow off valve is actually, more properly called a compressor bypass valve. Same name?