-
Hey Guest one of our sponsors Progressive Parts is running Black Friday and Cyber Monday offers - more details here
........................S17EW O
Guest
Ok so just to jump in i may be completely wrong. This is possibly different i work offshore and deal with prv's similar if not exact to a dv. The whole point in a prv/dv is that the dv unloads excess pressure by opening and releasing this pressure down streem. So if you have the dv on as per the norm then any excess pressure being forced onto the turbo would be vented to charge pipe.
On the other hand if you reverse your dv surely this means that the pressure in the charge pipe would cause the dv to open forcing the pressure back into the air intake and back against the turbo.
Could it not be that the excess pressure being put onto the turbo from the intake side could cause the turbo to be damaged.
Maybe wrong but just my 2p's worth.
Mark
On the other hand if you reverse your dv surely this means that the pressure in the charge pipe would cause the dv to open forcing the pressure back into the air intake and back against the turbo.
Could it not be that the excess pressure being put onto the turbo from the intake side could cause the turbo to be damaged.
Maybe wrong but just my 2p's worth.
Mark
S17EW O
Guest
i no nothing really tbh but think that makes sence, would like to hear of anyone else that can explain how reversing it doesnt damage anything...
reversing it does nothing different in the way it performs, its not a one way valve,
when the piston is compressed due to the vacuum from the manifold, it literally opens a gate, creating "in a nut shell" a through pipe
its vey much like a stop valve on a tap
when the piston is compressed due to the vacuum from the manifold, it literally opens a gate, creating "in a nut shell" a through pipe
its vey much like a stop valve on a tap
Right after reading this i may have changed my mind shall post as much as possible but reverse may be the better option.
How does a dump valve work ?
A blow-off valve is an air pressure bypass valve that is placed between the turbo compressor and the throttle.
When your turbocharged car is on boost, the entire intake system is filled with pressurised air; from the turbo compressor, through the throttle body and inlet manifold and into the combustion chambers. When the throttle is closed, this pressured air can no longer enter the engine. The only path available for the air is to try to flow back the way it came, through the turbo compressor the wrong way. This creates a fluttering noise on the blades of the still-spinning turbo compressor.
In addition to making this fluttering noise, a noise that is probably unwanted in a nice new turbo car (though actually extremely popular amongst modified-car enthusiasts!) it is often claimed that the load placed on the turbocharger from this pressurised air flowing through it the wrong way can cause premature wear or damage. The jury is still out on this, as it's quite difficult to directly attribute a turbo failure to not having a blow-off valve fitted. For that matter, we are yet to see a spectacularly damaged turbo from a street-driven car; they usually just plain wear out.
There are many other reasons car manufacturers fit blow-off valves to their cars, mainly to do with emissions, fuel economy and drivability. In aftermarket applications though, the main reasons for fitting a Dump Valve are to hold higher-than-standard boost levels, to give better throttle response (than a factory Dump Valve) by staying closed whenever it's not venting, and of course to make noise!
A blow-off valve (also called a compressor bypass valve or diverter valve) is a valve, generally a piston type, which is placed between the turbo compressor and the throttle to bypass the pressurised air on a closed throttle, either plumbing it back into the turbo inlet for silent operation, or to the atmosphere to make the signature blow-off valve whoosh.
How a blow off valve works
A blow-off valve is vacuum/pressure actuated piston-type valve. It uses vacuum/pressure signals to tell the piston when to open and close.
At idle there is engine vacuum on the top of the Dump Valve piston trying to suck it open, and no vacuum or pressure on the bottom of the piston. Since a vent-to-atmosphere Dump Valve needs to be shut at idle to avoid air being drawn in through it, there is a spring inside a Dump Valve with the job of holding the piston closed. The spring preload adjustment is to allow for differences in engine vacuum from car to car, and variations in atmospheric pressure at different elevations.
On airflow metered cars the air drawn in through an open vent-to-atmosphere Dump Valve at idle would confuse the ECU and cause over-fuelling and stalling and in any case, the air drawn in is unfiltered.
Under cruise conditions (off boost) the Dump Valve is experiencing similar conditions to when the car is at idle, but there is less vacuum present on top of the piston because the throttle is partly open. If the Dump Valve spring has been adjusted to keep the piston closed at idle, it will also be closed at cruise.
On boost there is boost pressure on both top and bottom of the Dump Valve, the forces from which counteract each other, so the Dump Valve remains closed.
Immediately after the throttle is closed under boost there is vacuum on the top of the piston and boost pressure on the bottom of the piston, which together, quickly open the Dump Valve to release the pressure. When the pressure has been released, the Dump Valve closes.
Which type of blow-off valve makes the fluttering or ‘pigeon' noise?
The short answer is that there is no blow-off valve that makes this noise. Read on to find out why.
Without a Dump Valve, the pressurised air being pumped into the engine by the turbo will have only one path when the throttle is closed: back through the turbo compressor. The fluttering sound is the sound of this air against the blades of the spinning turbo compressor as it tries to flow through it the wrong way.
Car manufacturers fit recirculating (plumb back) Dump Valves to give the pressurised air an alternate path when the throttle is closed: back into the turbo compressor inlet. This eliminates the ‘undesirable in a brand-new car' fluttering noise.
Aftermarket Dump Valves typically vent the pressurised air into the atmosphere for the purpose of making noise, and are characterised by the 'standard trumpet' sounds. Some other brands do different things with the air to make different noises, but this is not to be confused with the fluttering noise.
In some cases, aftermarket Dump Valves do not flow enough air either as a result of their design, or the way that they are adjusted. In this case, fitting an aftermarket blow-off valve will result in the fluttering noise being emitted from the turbo. While this is extremely popular, it is worth noting that if this is your objective, then simply removing the factory Dump Valve and replacing it with a pair of hose plugs would have been more cost-effective!
Incidentally, fitting a pod air filter can make any fluttering noise that was already present more audible. Also, large front-mounted intercoolers can increase the likelihood of ‘flutter' for any given Dump Valve, due to the larger volume of air present in the intake system. If the Dump Valve is any good, some adjustment of the spring preload would be all that is necessary to once again eliminate the flutter.
I'm having new intercooler piping made and I want to know where the best place to install the blow-off valve is?
There is not really any conclusive results that prove that one position is better than another, but many people have different ideas about this. Some say that it's best to have it close to the throttle, since that's where the back-pressure builds from when the butterfly is closed and it will respond quicker. Others say that it's better to put it as close to turbo as possible so that the valve is venting hot air rather than post-intercooler cold air, so that the inlet pipes after the intercooler are still filled with cool air.
Both positions have their merits, but are really of minute benefit. There is a trap to watch out for when mounting close to the turbo however. There is often a measurable pressure drop between the turbo and throttle body, especially as the RPM and hence the airflow increases. A Dump Valve uses two pressure signals to stay shut, one from the manifold and one from the inlet, which act on opposite sides of the piston and since they oppose each other they should balance out, and the spring then holds it shut.
The problem is when the revs rise and there becomes a pressure difference between the two signals. The pressure leaving the turbo may be say 16psi, while only 13 or 14 psi makes it to the manifold. So this means that there is 2 or 3 psi of pressure acting against the spring, which is enough to move the piston a fraction. In the Hybrid and Dump Valveus Maximus valves, since the outlets are staged and one is placed very close to the seat for rapid response this slight spring compression can be enough to open the valve a small amount. It is not a problem with the other valves in the range, and it depends on the flow efficiency of your intercooler and pipes, but for the Hybrid and Dump Valveus Maximus valves it is best to locate them after the intercooler.
If this problem does show up then it may also be a good idea to test the efficiency of your piping by measuring boost at redline just after the turbo, and after the throttle body. If there's any more than about 3 psi difference then your turbo is working harder than it needs to, and reducing this drop would help performance a lot.
Alot of reading but clears alot up and gives a clear understanding of the purpose of these valves and has made me consider reversing mine incase of possible turbo damage from back pressure and also possible advanced turbo spool
How does a dump valve work ?
A blow-off valve is an air pressure bypass valve that is placed between the turbo compressor and the throttle.
When your turbocharged car is on boost, the entire intake system is filled with pressurised air; from the turbo compressor, through the throttle body and inlet manifold and into the combustion chambers. When the throttle is closed, this pressured air can no longer enter the engine. The only path available for the air is to try to flow back the way it came, through the turbo compressor the wrong way. This creates a fluttering noise on the blades of the still-spinning turbo compressor.
In addition to making this fluttering noise, a noise that is probably unwanted in a nice new turbo car (though actually extremely popular amongst modified-car enthusiasts!) it is often claimed that the load placed on the turbocharger from this pressurised air flowing through it the wrong way can cause premature wear or damage. The jury is still out on this, as it's quite difficult to directly attribute a turbo failure to not having a blow-off valve fitted. For that matter, we are yet to see a spectacularly damaged turbo from a street-driven car; they usually just plain wear out.
There are many other reasons car manufacturers fit blow-off valves to their cars, mainly to do with emissions, fuel economy and drivability. In aftermarket applications though, the main reasons for fitting a Dump Valve are to hold higher-than-standard boost levels, to give better throttle response (than a factory Dump Valve) by staying closed whenever it's not venting, and of course to make noise!
A blow-off valve (also called a compressor bypass valve or diverter valve) is a valve, generally a piston type, which is placed between the turbo compressor and the throttle to bypass the pressurised air on a closed throttle, either plumbing it back into the turbo inlet for silent operation, or to the atmosphere to make the signature blow-off valve whoosh.
How a blow off valve works
A blow-off valve is vacuum/pressure actuated piston-type valve. It uses vacuum/pressure signals to tell the piston when to open and close.
At idle there is engine vacuum on the top of the Dump Valve piston trying to suck it open, and no vacuum or pressure on the bottom of the piston. Since a vent-to-atmosphere Dump Valve needs to be shut at idle to avoid air being drawn in through it, there is a spring inside a Dump Valve with the job of holding the piston closed. The spring preload adjustment is to allow for differences in engine vacuum from car to car, and variations in atmospheric pressure at different elevations.
On airflow metered cars the air drawn in through an open vent-to-atmosphere Dump Valve at idle would confuse the ECU and cause over-fuelling and stalling and in any case, the air drawn in is unfiltered.
Under cruise conditions (off boost) the Dump Valve is experiencing similar conditions to when the car is at idle, but there is less vacuum present on top of the piston because the throttle is partly open. If the Dump Valve spring has been adjusted to keep the piston closed at idle, it will also be closed at cruise.
On boost there is boost pressure on both top and bottom of the Dump Valve, the forces from which counteract each other, so the Dump Valve remains closed.
Immediately after the throttle is closed under boost there is vacuum on the top of the piston and boost pressure on the bottom of the piston, which together, quickly open the Dump Valve to release the pressure. When the pressure has been released, the Dump Valve closes.
Which type of blow-off valve makes the fluttering or ‘pigeon' noise?
The short answer is that there is no blow-off valve that makes this noise. Read on to find out why.
Without a Dump Valve, the pressurised air being pumped into the engine by the turbo will have only one path when the throttle is closed: back through the turbo compressor. The fluttering sound is the sound of this air against the blades of the spinning turbo compressor as it tries to flow through it the wrong way.
Car manufacturers fit recirculating (plumb back) Dump Valves to give the pressurised air an alternate path when the throttle is closed: back into the turbo compressor inlet. This eliminates the ‘undesirable in a brand-new car' fluttering noise.
Aftermarket Dump Valves typically vent the pressurised air into the atmosphere for the purpose of making noise, and are characterised by the 'standard trumpet' sounds. Some other brands do different things with the air to make different noises, but this is not to be confused with the fluttering noise.
In some cases, aftermarket Dump Valves do not flow enough air either as a result of their design, or the way that they are adjusted. In this case, fitting an aftermarket blow-off valve will result in the fluttering noise being emitted from the turbo. While this is extremely popular, it is worth noting that if this is your objective, then simply removing the factory Dump Valve and replacing it with a pair of hose plugs would have been more cost-effective!
Incidentally, fitting a pod air filter can make any fluttering noise that was already present more audible. Also, large front-mounted intercoolers can increase the likelihood of ‘flutter' for any given Dump Valve, due to the larger volume of air present in the intake system. If the Dump Valve is any good, some adjustment of the spring preload would be all that is necessary to once again eliminate the flutter.
I'm having new intercooler piping made and I want to know where the best place to install the blow-off valve is?
There is not really any conclusive results that prove that one position is better than another, but many people have different ideas about this. Some say that it's best to have it close to the throttle, since that's where the back-pressure builds from when the butterfly is closed and it will respond quicker. Others say that it's better to put it as close to turbo as possible so that the valve is venting hot air rather than post-intercooler cold air, so that the inlet pipes after the intercooler are still filled with cool air.
Both positions have their merits, but are really of minute benefit. There is a trap to watch out for when mounting close to the turbo however. There is often a measurable pressure drop between the turbo and throttle body, especially as the RPM and hence the airflow increases. A Dump Valve uses two pressure signals to stay shut, one from the manifold and one from the inlet, which act on opposite sides of the piston and since they oppose each other they should balance out, and the spring then holds it shut.
The problem is when the revs rise and there becomes a pressure difference between the two signals. The pressure leaving the turbo may be say 16psi, while only 13 or 14 psi makes it to the manifold. So this means that there is 2 or 3 psi of pressure acting against the spring, which is enough to move the piston a fraction. In the Hybrid and Dump Valveus Maximus valves, since the outlets are staged and one is placed very close to the seat for rapid response this slight spring compression can be enough to open the valve a small amount. It is not a problem with the other valves in the range, and it depends on the flow efficiency of your intercooler and pipes, but for the Hybrid and Dump Valveus Maximus valves it is best to locate them after the intercooler.
If this problem does show up then it may also be a good idea to test the efficiency of your piping by measuring boost at redline just after the turbo, and after the throttle body. If there's any more than about 3 psi difference then your turbo is working harder than it needs to, and reducing this drop would help performance a lot.
Alot of reading but clears alot up and gives a clear understanding of the purpose of these valves and has made me consider reversing mine incase of possible turbo damage from back pressure and also possible advanced turbo spool
S17EW O
Guest
Nothing in that has any bearing on which way round a Forge 007 recirc valve is fitted.
I run mine reversed.
That is because I believe it is the logical way to fit it.
Also, with my level of boost, it doesn't sound gay.
That is because I believe it is the logical way to fit it.
Also, with my level of boost, it doesn't sound gay.
Similar threads
