Forge VTA Bypass Valve Information; Forge's Response
03-04-2013, 01:33 PM
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Forge VTA Bypass Valve Information; Forge's Response
Hey guys,
I thought I would create a thread with information regarding the Forge VTA Bypass Valve that is quick and concise! I know there's another thread with most of this information, but not having to sift through theories and stuff like that is kind of nice. Don't hate me
But basically when I go over 10psi it flutters, anything under it's a smooth psssss.
An engineer from Forge emailed me with this response.
After I inquiring about "flutter dump" which is a form of compressor surge according to Synapse Engineering he responded with this;
Here's the response he had when I asked about other set-ups on the same platform and others not exhibiting the same sound as mine. The second question I asked was if a even lighter spring should be used for cars in higher altitudes. Since there's less atmospheric pressure, I assumed that it's harder to make vacuum thus a lighter spring should be used. Here's his response;
So basically, if you take their response to heart, this is not bad. It's normal and shouldn't cause problems. The thing that is a cause for concern for me is it doesn't happen to the stock bypass valve, but as he states, the dual piston action can cause this uncomforting sound.
Hope this helps people more so than annoys.
Respectfully,
Vahdyx
***edit***
Update; I removed and returned the FORGE VTA Bypass and installed stock. The noise doesn't happen and I feel much better
I thought I would create a thread with information regarding the Forge VTA Bypass Valve that is quick and concise! I know there's another thread with most of this information, but not having to sift through theories and stuff like that is kind of nice. Don't hate me
But basically when I go over 10psi it flutters, anything under it's a smooth psssss.
An engineer from Forge emailed me with this response.
Let me start off by confirming that the sound you are hearing is absolutely NOT compressor surge by any measure whatsoever.
Actual compressor surge is a phenomenon that occurs only at a wide open throttle condition, under full load and full boost when the turbocharger is flowing more air than the head of the motor can physically ingest. Power output will cease to climb beyond the airflow threshold of the head, and all additional airflow will revert out of the compressor inlet. A video of actual compressor surge can be seen here.
True Compressor Surge - YouTube
Compressor surge does NOT occur under any throttle lift condition especially with a functional wastegate and bypass valve on the car. Both a wastegate and a bypass valve of any type are failsafes against compressor surge, so if the valve is venting at all when you lift off the throttle, then surge cannot physically occur.
The sound that you are hearing is just a fluttering effect from the valve as it is responding to the pressure differential that controls it. The valve will react to both the pressure within the charge piping as well as to the small vacuum line reference to the top of it, so as the piston moves back and forth responding to these references, it can create varying sounds under different conditions.
Additionally, it also appears that the sound is being amplified by the resonance through the intake system on the vehicle. Even completely stock factory valves will exhibit fluttering in response to these pressure differentials, however, you will generally not hear the sound due to the recirculating nature of the valve and the heavy baffling of the intake system that will muffle the sound. The sound is now being amplified by the atmospheric nature of the valve.
Another aspect to consider is that our atmospheric valve for this application uses a unique dual counter-spring piston design to help aid in compatibility on MAF sensor applications. This feature, which is completely unique to our atmospheric valve products, can sometimes result in an exaggerated fluttering sound as the two pistons can open and close independently in response to their respective references. This is completely normal and not a problem in any way whatsoever for the turbo, nor any other mechanical part of the engine nor the electronics.
Everything appears to be operating perfectly normally.
Actual compressor surge is a phenomenon that occurs only at a wide open throttle condition, under full load and full boost when the turbocharger is flowing more air than the head of the motor can physically ingest. Power output will cease to climb beyond the airflow threshold of the head, and all additional airflow will revert out of the compressor inlet. A video of actual compressor surge can be seen here.
True Compressor Surge - YouTube
Compressor surge does NOT occur under any throttle lift condition especially with a functional wastegate and bypass valve on the car. Both a wastegate and a bypass valve of any type are failsafes against compressor surge, so if the valve is venting at all when you lift off the throttle, then surge cannot physically occur.
The sound that you are hearing is just a fluttering effect from the valve as it is responding to the pressure differential that controls it. The valve will react to both the pressure within the charge piping as well as to the small vacuum line reference to the top of it, so as the piston moves back and forth responding to these references, it can create varying sounds under different conditions.
Additionally, it also appears that the sound is being amplified by the resonance through the intake system on the vehicle. Even completely stock factory valves will exhibit fluttering in response to these pressure differentials, however, you will generally not hear the sound due to the recirculating nature of the valve and the heavy baffling of the intake system that will muffle the sound. The sound is now being amplified by the atmospheric nature of the valve.
Another aspect to consider is that our atmospheric valve for this application uses a unique dual counter-spring piston design to help aid in compatibility on MAF sensor applications. This feature, which is completely unique to our atmospheric valve products, can sometimes result in an exaggerated fluttering sound as the two pistons can open and close independently in response to their respective references. This is completely normal and not a problem in any way whatsoever for the turbo, nor any other mechanical part of the engine nor the electronics.
Everything appears to be operating perfectly normally.
As I have stated, the sound you are hearing is NOT compressor surge.
It is simply the dual piston configuration of the valve responding to the pressure differential that actuates it, and the sound is exaggerated because the valve is venting to the atmosphere instead of recirculating.
If you had a recirculating style of valve, it would flutter as well. You OEM valve also flutters under certain conditions. ALL mechanical valves flutter in response to their respective pressure differential. You just wouldn't hear it because the air is vented back into the intake instead of to the atmosphere.
We are the world's largest manufacturer of application specific and universal valve products. It has been our specialty and core market for the last 15 years. Other companies produce 1 or 2 styles of valve, and then have dozens of adapters to fit them to different applications whereas we offer application specific products engineered to offer the best performance for the given vehicle. We have been evolving and refining our products each year to ensure that they perform optimally, and would not release something to the market if it cause a problem.
Compressor surge is the most commonly misunderstood phenomenon in the turbo world, primarily because people use terms without fully understanding what they actually mean. Just because something exhibits a surge-like sound does not mean it is actually compressor surge.
It is simply the dual piston configuration of the valve responding to the pressure differential that actuates it, and the sound is exaggerated because the valve is venting to the atmosphere instead of recirculating.
If you had a recirculating style of valve, it would flutter as well. You OEM valve also flutters under certain conditions. ALL mechanical valves flutter in response to their respective pressure differential. You just wouldn't hear it because the air is vented back into the intake instead of to the atmosphere.
We are the world's largest manufacturer of application specific and universal valve products. It has been our specialty and core market for the last 15 years. Other companies produce 1 or 2 styles of valve, and then have dozens of adapters to fit them to different applications whereas we offer application specific products engineered to offer the best performance for the given vehicle. We have been evolving and refining our products each year to ensure that they perform optimally, and would not release something to the market if it cause a problem.
Compressor surge is the most commonly misunderstood phenomenon in the turbo world, primarily because people use terms without fully understanding what they actually mean. Just because something exhibits a surge-like sound does not mean it is actually compressor surge.
You are focusing far too much on the specific sound.
The actual sound produced is going to vary under innumerable circumstances, such as varying degrees of throttle position, load levels, boost levels, other supporting modifications, and yes potentially altitude as well. The volume, tone, and level of fluttering will change based on all of these contributing factors. It is a mechanical valve that operates on a pressure differential, so it has a mechanical curve to its operation and the subsequent sound produced, so there is no way to guarantee that you setup will sound exactly like that of someone else.
Especially when you are comparing sounds based on videos taken with likely different camera and audio equipment at potentially different quality levels.
The simple fact of the matter is, the sounds that your valve is producing are perfectly normal based on all current information.
The actual sound produced is going to vary under innumerable circumstances, such as varying degrees of throttle position, load levels, boost levels, other supporting modifications, and yes potentially altitude as well. The volume, tone, and level of fluttering will change based on all of these contributing factors. It is a mechanical valve that operates on a pressure differential, so it has a mechanical curve to its operation and the subsequent sound produced, so there is no way to guarantee that you setup will sound exactly like that of someone else.
Especially when you are comparing sounds based on videos taken with likely different camera and audio equipment at potentially different quality levels.
The simple fact of the matter is, the sounds that your valve is producing are perfectly normal based on all current information.
So basically, if you take their response to heart, this is not bad. It's normal and shouldn't cause problems. The thing that is a cause for concern for me is it doesn't happen to the stock bypass valve, but as he states, the dual piston action can cause this uncomforting sound.
Hope this helps people more so than annoys.
Respectfully,
Vahdyx
***edit***
Update; I removed and returned the FORGE VTA Bypass and installed stock. The noise doesn't happen and I feel much better
Last edited by vahdyx; 03-11-2013 at 01:04 AM.
03-04-2013, 02:00 PM
#3
Hey guys,
I thought I would create a thread with information regarding the Forge VTA Bypass Valve that is quick and concise! I know there's another thread with most of this information, but not having to sift through theories and stuff like that is kind of nice. Don't hate me
Forge VTA Bypass Valve Assembly - YouTube
Forge Motorsports VTA Bypass Valve sound or surge - YouTube
An engineer from Forge emailed me with this response.
So basically, if you take their response to heart, this is not bad. It's normal and shouldn't cause problems. The thing that is a cause for concern for me is it doesn't happen to the stock bypass valve, but as he states, the dual piston action can cause this uncomforting sound.
Hope this helps people more so than annoys.
Respectfully,
Vahdyx
I thought I would create a thread with information regarding the Forge VTA Bypass Valve that is quick and concise! I know there's another thread with most of this information, but not having to sift through theories and stuff like that is kind of nice. Don't hate me
Forge VTA Bypass Valve Assembly - YouTube
Forge Motorsports VTA Bypass Valve sound or surge - YouTube
An engineer from Forge emailed me with this response.
So basically, if you take their response to heart, this is not bad. It's normal and shouldn't cause problems. The thing that is a cause for concern for me is it doesn't happen to the stock bypass valve, but as he states, the dual piston action can cause this uncomforting sound.
Hope this helps people more so than annoys.
Respectfully,
Vahdyx
Nice! I'm glad you got that situated.
And one other thing, on Drazens Saab 93 he made a Cold Air intake and his car sounded like it was fluttering on the stock bypass. so that makes sense with what they are saying.
03-04-2013, 03:49 PM
#4
That is not caused by the bpv, that's air hitting the turbine blades, valve is not letting all the air out. I call bs on them, iv been fooling around with my bpv and when it isn't opening right I get the same sound, when it is opening right I don't get that sound.
03-04-2013, 06:34 PM
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Well, could be, but even Modern Performance says this is normal and sounds fine. They said the Dodge Dart also makes similar noises.
03-05-2013, 10:43 AM
#6
right, and as i said. Drazen's Saab 9-3 makes flutter sounds when he shifts on stock by pass. its just extremely loud cause he has a CAI now instead of his normal intake, which made it really quiet
03-05-2013, 10:53 AM
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You are right, it could be a defect, but then again I don't think that the guy from Forge would have went thru and explained in detail as he did if it was simply just a defect. Which Forge offers a warranty so it wouldn't be a big deal. I have heard this new Vent to Atmosphere on 2 seperate Cobalts and they both sound the same. So I just think that's the way it is.
03-05-2013, 11:32 AM
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I updated the original post to include our most significant recent email. I brought up flutter dump, and quoted his response.
03-05-2013, 11:39 AM
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I don't understand why you are trying to argue with the engineer of the company? I understand that the sound may be annoying you which in that case I have a stock on I will sell you. Things are going to sound different on different cars, conditions, load and etc. He has done a very good job explaining compressor surge, which a lot of people do not understand. To be honest the only reason I know is because I was at 2 different dyno's where it had happened to the car. I was then taught about it by two different respectable builders and went from there. I would just quit trying to argue with someone who is far more educated on the topic then you are. That's just my opinion
03-05-2013, 11:47 AM
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I don't understand why you are trying to argue with the engineer of the company? I understand that the sound may be annoying you which in that case I have a stock on I will sell you. Things are going to sound different on different cars, conditions, load and etc. He has done a very good job explaining compressor surge, which a lot of people do not understand. To be honest the only reason I know is because I was at 2 different dyno's where it had happened to the car. I was then taught about it by two different respectable builders and went from there. I would just quit trying to argue with someone who is far more educated on the topic then you are. That's just my opinion
Also prior to that email I had no idea what "flutter dump" was! The expression was emailed to me and I asked about it. So I'm not the only one with these concerns. This thread is intended to help, not to attack Forge
03-05-2013, 11:50 AM
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I'm not claiming knowledge on the topic at all nor am I "arguing" per say. I'm just trying to get as much information and attack it at all angles (devils advocate if you will) to get the most information on this topic in a clear and concise way. The point of this is to get as much info on it in one spot, in one post.
03-05-2013, 11:51 AM
#12
03-05-2013, 07:46 PM
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So I'm thinking about upgrading to this forge and just wondering how many people with hp tuners is running this? I've talked to one member already with hpt and he said he hasn't had a problem with this piece at all.
03-05-2013, 11:54 PM
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I had that exact sound on my stock BPV when I did the vacuum tank delete. It concerned me so I put it back to normal. If that's the case I may do the vacuum tank delete again lol
03-06-2013, 12:10 AM
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I added another message from him. I asked about higher altitudes and other cars not having the same noise as me. I asked him if he could elaborate.
03-06-2013, 12:34 AM
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Thank GOD someone with proper education has explained actual compressor surge. I get so annoyed with all the BOV flutter videos and comments calling it surge.
In my opinion, I agree with tomj77. While this sound you're hearing isn't compressor surge, it is trapped air slapping back to the blades. You have to understand that even though this engineer is very well educated, he works for the company and has a vested interest in making sure he saves face. Basically a conflict of interest. You would do yourself a service to obtain consult from a neutral engineer who has nothing to lose or gain. Lucky for you, you don't need it as you have GM to rely on. Ask yourself how the car works stock. I have NEVER heard the stock BPV flutter more than one little "ch" before.
If you're dead set on using something VTA, I would suggest the Synapse Synchronic. The tech behind that beautiful BOV (they make BPVs too) is amazing. Mine never fluttered EVER on the BNR setup.
Thx for posting this.
In my opinion, I agree with tomj77. While this sound you're hearing isn't compressor surge, it is trapped air slapping back to the blades. You have to understand that even though this engineer is very well educated, he works for the company and has a vested interest in making sure he saves face. Basically a conflict of interest. You would do yourself a service to obtain consult from a neutral engineer who has nothing to lose or gain. Lucky for you, you don't need it as you have GM to rely on. Ask yourself how the car works stock. I have NEVER heard the stock BPV flutter more than one little "ch" before.
If you're dead set on using something VTA, I would suggest the Synapse Synchronic. The tech behind that beautiful BOV (they make BPVs too) is amazing. Mine never fluttered EVER on the BNR setup.
Thx for posting this.
09-20-2013, 07:38 AM
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Thank GOD someone with proper education has explained actual compressor surge. I get so annoyed with all the BOV flutter videos and comments calling it surge.
In my opinion, I agree with tomj77. While this sound you're hearing isn't compressor surge, it is trapped air slapping back to the blades. You have to understand that even though this engineer is very well educated, he works for the company and has a vested interest in making sure he saves face. Basically a conflict of interest. You would do yourself a service to obtain consult from a neutral engineer who has nothing to lose or gain. Lucky for you, you don't need it as you have GM to rely on. Ask yourself how the car works stock. I have NEVER heard the stock BPV flutter more than one little "ch" before.
If you're dead set on using something VTA, I would suggest the Synapse Synchronic. The tech behind that beautiful BOV (they make BPVs too) is amazing. Mine never fluttered EVER on the BNR setup.
Thx for posting this.
In my opinion, I agree with tomj77. While this sound you're hearing isn't compressor surge, it is trapped air slapping back to the blades. You have to understand that even though this engineer is very well educated, he works for the company and has a vested interest in making sure he saves face. Basically a conflict of interest. You would do yourself a service to obtain consult from a neutral engineer who has nothing to lose or gain. Lucky for you, you don't need it as you have GM to rely on. Ask yourself how the car works stock. I have NEVER heard the stock BPV flutter more than one little "ch" before.
If you're dead set on using something VTA, I would suggest the Synapse Synchronic. The tech behind that beautiful BOV (they make BPVs too) is amazing. Mine never fluttered EVER on the BNR setup.
Thx for posting this.
09-20-2013, 04:23 PM
#20
People should be aware of the 2 different BPV's offered by Forge. You have the VTA there is also a recirc. They are different. Very different.
If you are NOT tuning for Atmospheric venting then it will not work right.
Forge:
If you are not tuned for blow off the recirc is the stock replacement.
If you are NOT tuning for Atmospheric venting then it will not work right.
Forge:
"When installed on any GM vehicle to avoid the possibility of a P0101 trouble code the ECM must be reprogrammed with a tune optimized for atmospheric discharge. We recommend the tuning services of Trifecta Performance: www.trifectaperformance.com"
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