Turbo Induction Noises and Bosch Diverter Valves
02-01-2002, 12:47 PM
#16
Instructor
Mr Chicken is correct.
While there have been several revisions to the Bosch design, all of them are still based on the original rubber diaphram configuration.
Revisions have included stiffer springs and various weights fastened to the diaphram to prevent harmonic occilations, yet the real weak point of the rubber diaphram design is the rubber diaphram itself.
The diaphram pivots up and down during boost venting, and eventually tears at the outer edge where it is pivoting. The later revisions are better at holding boost when they are functioning, but they are susceptible to the same tearing as the original versions.
The Bailey unit uses a high temp nylon piston instead of a rubber diaphram. More costly to produce, but it is impervious to failure.
While there have been several revisions to the Bosch design, all of them are still based on the original rubber diaphram configuration.
Revisions have included stiffer springs and various weights fastened to the diaphram to prevent harmonic occilations, yet the real weak point of the rubber diaphram design is the rubber diaphram itself.
The diaphram pivots up and down during boost venting, and eventually tears at the outer edge where it is pivoting. The later revisions are better at holding boost when they are functioning, but they are susceptible to the same tearing as the original versions.
The Bailey unit uses a high temp nylon piston instead of a rubber diaphram. More costly to produce, but it is impervious to failure.
02-04-2002, 12:45 AM
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Also, Todd from EVO motorsports reports the use of a 50/50 valve, that vents some gas to the atmosphere, creating the desired sound, without tripping the motronic.
02-04-2002, 01:22 PM
#18
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[quote]Originally posted by cjv:
<strong>I've read this thread with interest, yet I'm still a little confused. On a modified engine which valve is better Bailey or Forge? Why?
</strong><hr></blockquote>
CJV,
Before we began importing the Bailey Motorsport unit, we did extensive research on all the alloy replacement valves on the market. At that time, there were no official importers of any of these valves in the US, so we were not limited by brand. There were even representatives selling other brands in Europe that suggested using the Bailey Motorsport unit instead!
There does not seem to be much public information regarding any alloy replacement valve on the rennlist, so you would be better served doing a search on a site like Audiworld.com. Specifically search the S4 forum there, as there are many telling posts regarding relative quality.
[quote]Originally posted by A.J. O'Connell:
<strong>Also, Todd from EVO motorsports reports the use of a 50/50 valve, that vents some gas to the atmosphere, creating the desired sound, without tripping the motronic.</strong><hr></blockquote>
Our research regarding atmospheric type valves has shown us different results.
Ultimately, the use of a diverter valve that releases boost to the atmosphere during part and WOT, no matter how little boost, results in maladaptation of fuel curves on the Bosch Motronic systems. It is even worse on the DBW Bosch ME7 systems.
If a valve is releasing any boost to the atmosphere, it is pulling air through the Mass Air Flow meter (MAF) that is not being used by the engine. However, since this air is being registered by the MAF, the fuel injection ECU assumes that the air is being used by the engine, and richens mixture accordingly. After several days of driving, this incorrect adaptation results in poor drivability, especially at part throttle, and ultimately a check engine light is illuminated as the adaptation percentage reaches a trigger point.
The only time we have seen an atmospheric vent type valve (also known as a Blow Off Valve) seem to work, is if the setting on the internal spring is set so that there is no release of boost at part throttle.
Tightening the spring so that it only allows the valve to open under full manifold vacuum results in proper full load lift off venting, which will not affect fuel trim adaptation routines noticeably, since the ECU is mainly in open loop during this phase of operation (fixed fueling maps, though there is *some* WOT adaptation on ME7 systems).
However, if no venting is permitted during part throttle load operation, the turbo is working against the boost it is producing as it is restricted by the partially closed throttle plate. This is in direct contradiction to the intended purpose of a boost bypass/vent system.
The bottom line: we have never seen a Blow Off Valve system work 100% successfully on a MAF equipped car.
<strong>I've read this thread with interest, yet I'm still a little confused. On a modified engine which valve is better Bailey or Forge? Why?
</strong><hr></blockquote>CJV,
Before we began importing the Bailey Motorsport unit, we did extensive research on all the alloy replacement valves on the market. At that time, there were no official importers of any of these valves in the US, so we were not limited by brand. There were even representatives selling other brands in Europe that suggested using the Bailey Motorsport unit instead!
There does not seem to be much public information regarding any alloy replacement valve on the rennlist, so you would be better served doing a search on a site like Audiworld.com. Specifically search the S4 forum there, as there are many telling posts regarding relative quality.
[quote]Originally posted by A.J. O'Connell:
<strong>Also, Todd from EVO motorsports reports the use of a 50/50 valve, that vents some gas to the atmosphere, creating the desired sound, without tripping the motronic.</strong><hr></blockquote>
Our research regarding atmospheric type valves has shown us different results.
Ultimately, the use of a diverter valve that releases boost to the atmosphere during part and WOT, no matter how little boost, results in maladaptation of fuel curves on the Bosch Motronic systems. It is even worse on the DBW Bosch ME7 systems.
If a valve is releasing any boost to the atmosphere, it is pulling air through the Mass Air Flow meter (MAF) that is not being used by the engine. However, since this air is being registered by the MAF, the fuel injection ECU assumes that the air is being used by the engine, and richens mixture accordingly. After several days of driving, this incorrect adaptation results in poor drivability, especially at part throttle, and ultimately a check engine light is illuminated as the adaptation percentage reaches a trigger point.
The only time we have seen an atmospheric vent type valve (also known as a Blow Off Valve) seem to work, is if the setting on the internal spring is set so that there is no release of boost at part throttle.
Tightening the spring so that it only allows the valve to open under full manifold vacuum results in proper full load lift off venting, which will not affect fuel trim adaptation routines noticeably, since the ECU is mainly in open loop during this phase of operation (fixed fueling maps, though there is *some* WOT adaptation on ME7 systems).
However, if no venting is permitted during part throttle load operation, the turbo is working against the boost it is producing as it is restricted by the partially closed throttle plate. This is in direct contradiction to the intended purpose of a boost bypass/vent system.
The bottom line: we have never seen a Blow Off Valve system work 100% successfully on a MAF equipped car.
02-04-2002, 02:04 PM
#19
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I was wondering, is it possible to experience problem of the diverter valve without hearing the hooking sound?
I felt a slight decrease in power/boost during mid range after replacing my 01 engine to an 02 engine. But I have yet heard of any 'hooking'. But the overall feel of the engine is very unresponsive.
I felt a slight decrease in power/boost during mid range after replacing my 01 engine to an 02 engine. But I have yet heard of any 'hooking'. But the overall feel of the engine is very unresponsive.
02-04-2002, 02:05 PM
#20
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Thread Starter
CJV; My research so far says that only a few basic things; The OEM Bosch unit is prone to failure. The failure is caused by the rubber diaprhagm that acts as its' operating part. The two relatively known replacment units available in the after-market; Bailey and Forge do not use diaphragms. They use pistons either of alloy or delrin. The replacement units can be disassembled and the springs can be exchanged within them. A well known tuner has been using the Forge valve with success.
The Audi people have used both and there are advocates for either. The Bailey has a threaded vacuum line at the top that may be changed for a 90 degree fitting that may facilitate the installation into the tight confines of a 996TT.
I have only personally seen the Forge unit (I purchased two of them for possible installation). The part looks quality and the visual difference to the Bosch can only be made on an external basis as the Bosch cannot be easily disassembled. The Bosch is as one might imagine of a mass produced unit mostly of plastic molding. The competitors are "Turnings" probably done on CNC machines.
I cannot state with any authority which one would be better. My SENSE is that both are fine units and would work quite well in replacement.
The Audi people have used both and there are advocates for either. The Bailey has a threaded vacuum line at the top that may be changed for a 90 degree fitting that may facilitate the installation into the tight confines of a 996TT.
I have only personally seen the Forge unit (I purchased two of them for possible installation). The part looks quality and the visual difference to the Bosch can only be made on an external basis as the Bosch cannot be easily disassembled. The Bosch is as one might imagine of a mass produced unit mostly of plastic molding. The competitors are "Turnings" probably done on CNC machines.
I cannot state with any authority which one would be better. My SENSE is that both are fine units and would work quite well in replacement.
02-04-2002, 04:32 PM
#21
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The Forge 007P is soon to be avilable with the 90 degree fittinf on the top. this will be a metal fiiting.
The internals of the Forge valves are manufactured from aluminium , this will alow greater stability at over 200 degrees.
We have many types of Diverter and blow off valves for many applications, We have blow off valves that will perform perfectly well on many cars with MAF, Subaru WRX, Mitsubishi Evo, Ford , Fiat etc.
We design a valve that is specific for the intended application.
If any guys would like to try an atmno valve I would be happy to oblige.
We will be sending Garey the newstyle valves soon
The internals of the Forge valves are manufactured from aluminium , this will alow greater stability at over 200 degrees.
We have many types of Diverter and blow off valves for many applications, We have blow off valves that will perform perfectly well on many cars with MAF, Subaru WRX, Mitsubishi Evo, Ford , Fiat etc.
We design a valve that is specific for the intended application.
If any guys would like to try an atmno valve I would be happy to oblige.
We will be sending Garey the newstyle valves soon
02-05-2002, 12:55 PM
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WILLIAM996TT
You had to have an engine swapped??? Zoinks!
[quote]I was wondering, is it possible to experience problem of the diverter valve without hearing the hooking sound?
I felt a slight decrease in power/boost during mid range after replacing my 01 engine to an 02 engine. But I have yet heard of any 'hooking'. But the overall feel of the engine is very unresponsive.<hr></blockquote>
I first started to feel surging under acceleration and occasional losses of power. I did eventually here the "honking".
Past experiences with my Audi have shown that the Bosch units are trash. Myself and other Audi owners did realize when they fail they may show different characteristics. Some people heard noises, some did not. All in all tons of people were going slower and it was no fault of their own. It was the valves.
My suggestion is to just upgrade and be done with it.
I hope this answered your question.
You had to have an engine swapped??? Zoinks!
[quote]I was wondering, is it possible to experience problem of the diverter valve without hearing the hooking sound?
I felt a slight decrease in power/boost during mid range after replacing my 01 engine to an 02 engine. But I have yet heard of any 'hooking'. But the overall feel of the engine is very unresponsive.<hr></blockquote>
I first started to feel surging under acceleration and occasional losses of power. I did eventually here the "honking".
Past experiences with my Audi have shown that the Bosch units are trash. Myself and other Audi owners did realize when they fail they may show different characteristics. Some people heard noises, some did not. All in all tons of people were going slower and it was no fault of their own. It was the valves.
My suggestion is to just upgrade and be done with it.
I hope this answered your question.
02-05-2002, 01:13 PM
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I have installed the Forge DV valves on many customers 996TT cars. The installation is straightforward, however is a bit time consuming. The limited space and method in which they are secured makes the job more difficult. With some patience and about 2 hours, the valves can be installed. We started including the Forge DV valves in our tuning systems due to the past experience that we had with the faulty Audi/VW units. The Forge units are an excellent upgrade and priced right. We sell a 996TT Forge DV kit with instructions and associated hardware.
02-05-2002, 01:36 PM
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Mr. Zuccone
1st question.
Earlier in the thread A.J. O'Connell mentioned a 50/50 valve. Can you give me the skinny on those?
How do you get a blow off valve to work with a MAF and not have the car run rich?
2nd question.
When I was searching for a valve for my Audi, I came across the Forge valve. One of the issues I did not like was the fact that it was rebuilable. To me that meant it had to be serviced. I liked the Bailey because there was no service necessary. How often do have to service the units?
BTW- I like your website. I have it bookmarked
1st question.
Earlier in the thread A.J. O'Connell mentioned a 50/50 valve. Can you give me the skinny on those?
How do you get a blow off valve to work with a MAF and not have the car run rich?
2nd question.
When I was searching for a valve for my Audi, I came across the Forge valve. One of the issues I did not like was the fact that it was rebuilable. To me that meant it had to be serviced. I liked the Bailey because there was no service necessary. How often do have to service the units?
BTW- I like your website. I have it bookmarked
02-05-2002, 02:14 PM
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Woops,
Answer: 1st question.
Earlier in the thread A.J. O'Connell mentioned a 50/50 valve. Can you give me the skinny on those?
How do you get a blow off valve to work with a MAF and not have the car run rich?
We have tested a 50/50 valve on VW 1.8T applications. We have no conclusive results as to the benefits and/or improvements. We HAVE NOT and WILL NOT put these 50/50 valves on a Porsche 996TT. THEY WILL NOT FIT. Second, the only reason we have tried them on the VW cars, is the customers want the sound. They want to hear he blow off sound in between shifts.
Answer: 2nd question.
When I was searching for a valve for my Audi, I came across the Forge valve. One of the issues I did not like was the fact that it was rebuilable. To me that meant it had to be serviced. I liked the Bailey because there was no service necessary.
How often do have to service the units?
Lets face it, nothing lasts forever! I view the fact that the FORGE is rebuildable as a benefit. Why spend the $$ for a throwaway part? If that is the case, just keep the Bosch units and have the dealer replace them for free under warranty each time they fail. There are about 8000 Forge valves operating here in the states with excellent success. Both the Forge and the Bailey valves have parts that can and will wear out at some point in its life. The Forge DV has a lifetime warranty with free parts replacement. I like the fact that they can be rebuilt if they need it. I honestly think that both products are better then the OEM part, I have used and installed the FORGE on the 996TT and am very please with the results.
Answer: 1st question.
Earlier in the thread A.J. O'Connell mentioned a 50/50 valve. Can you give me the skinny on those?
How do you get a blow off valve to work with a MAF and not have the car run rich?
We have tested a 50/50 valve on VW 1.8T applications. We have no conclusive results as to the benefits and/or improvements. We HAVE NOT and WILL NOT put these 50/50 valves on a Porsche 996TT. THEY WILL NOT FIT. Second, the only reason we have tried them on the VW cars, is the customers want the sound. They want to hear he blow off sound in between shifts.
Answer: 2nd question.
When I was searching for a valve for my Audi, I came across the Forge valve. One of the issues I did not like was the fact that it was rebuilable. To me that meant it had to be serviced. I liked the Bailey because there was no service necessary.
How often do have to service the units?
Lets face it, nothing lasts forever! I view the fact that the FORGE is rebuildable as a benefit. Why spend the $$ for a throwaway part? If that is the case, just keep the Bosch units and have the dealer replace them for free under warranty each time they fail. There are about 8000 Forge valves operating here in the states with excellent success. Both the Forge and the Bailey valves have parts that can and will wear out at some point in its life. The Forge DV has a lifetime warranty with free parts replacement. I like the fact that they can be rebuilt if they need it. I honestly think that both products are better then the OEM part, I have used and installed the FORGE on the 996TT and am very please with the results.
02-05-2002, 02:27 PM
#28
Instructor
Actually, the Bailey Motorsport valves are also rebuildable. The body is held together with allen cap screws.
However, Bailey does not have a recommended service schedule. The materials and tolerance of the Bailey units permit lifetime lubrication via PCV oil. We have never had a valve stick due to lubrication issues out of the thousands we have imported into the US since late 1999.
There is a lifetime warranty on the Bailey Motorsports valves, too.
More fuel for the fire!
However, Bailey does not have a recommended service schedule. The materials and tolerance of the Bailey units permit lifetime lubrication via PCV oil. We have never had a valve stick due to lubrication issues out of the thousands we have imported into the US since late 1999.
There is a lifetime warranty on the Bailey Motorsports valves, too.
More fuel for the fire!
02-05-2002, 02:41 PM
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Todd,
I am glad you brought that up. It seems that the playing field is even. It is good to hear that Bailey valve is serviceable like the Forge. I guess that means that they both can and will need to be serviced at some point in their life.
I am glad you brought that up. It seems that the playing field is even. It is good to hear that Bailey valve is serviceable like the Forge. I guess that means that they both can and will need to be serviced at some point in their life.
