Internal/external Waste gates and blow off valves, recirculating/venting to atmosphere and boost controllers?
Now, I have (quite) a few questions, that may or may not be somewhat rhetoric, but haven't seen anything else on the forum that really addresses this (particularly in regards to the turbo setup in the 4c). Also may be for the benefit of some members who are still getting confused, particularly in highlighting, not only the benefits of mods, but the difference between what a
-Turbo waste gate/actuator is, and what a
Diverter blow off valve is, and
-Whether both are internally recirculating, or
-"Dumped/vented to atmosphere,
Both wastegate and bloff off valve in our cases are recirculating are they not?
-Any point in adding aftermarket mechanical or electronic boost controllers?
i.e what are the
benefits in boost/power?
benefits in better quality/longevity over OEM plastic parts and weak springs/components? For an aftrmarket blow off valve,, i like more sound i.e
the benefit of controlling the sound of how loud the blow off valve vents to atmosphere?
and
What sounds do we hear from the engine,?? Is the distinctive "barp" sound between shifts coming from the waste gate recirculating (or venting ) exhaust to control turbo boost, or is it the diverter/blow off valve recirculating (or once again venting to atmosphere) the pressurized intake air?
Now a lot of people are confused with the difference between a waste gate and a blow off valve. They are two complete different things as we may or may not know..
WG: Regulates pressure on the exhaust side i.e turbo boost
BOV: Regulates pressure on the intake side. Stops excessive flow back pressure on the turbo vanes after the throttle plate close
As far as i know, This limit is controlled by the waste gate , which "sees" the intake pressure and opens up when the limit is reached to vent off or bypass the exhaust gas around the turbo (vented to the catalytic converter or atmosphere), thus preventing it from spinning faster and creating more boost. It doesn't vent out the intake air.
Hence , the waste gate controls the maximum boost pressure (limited by how much your engine can take/ turbo rev limit etc). Changing how much your waste gate "sees" can allow you to increase this limit (increase maximum boost)
A blow off valve, on the other hand, lies on the intake side and is meant to open up when the throttle is closed (by sensing engine vacuum). This vents out the pressurized intake air to the atmosphere. This is required because as you rev the engine up , the turbo spools up as well. The instant the throttle is let go, the turbo continues to create boost which now has no where to go. This causes the turbo to quickly spool down which creates a lot of impulsive stress on the turbo. Consequently , the turbo (now having spooled down) will take time to spool up when the throttle is re-applied.
Hence the blow-off valve protects your turbo by allow it to continue to spin (rotational inertia) and vent out the un-required air, when the throttle is closed. A consequence of which is reduced turbo lag eg. between gear shifts etc. Installing high flow blow off valves may improve turbo spool performance to a perceivable extent.
Poor bov design chirping
like when the throttle closes during a shift. When a BOV is vented to atmosphere, it produces a distinctive hissing sound, and when a BOV isn’t used or is of insufficient size, the compressor surges and makes a chirping or rattling sound. Compressor surge can put stress on the compressor and its bearings, shortening its life. I hear this chirpping all the time, meaning the oem blow off valve, being plastic is not that good...i.e plastic
Quote,
For cars with metered air (a flapper valve or hot wire MAF sensor), it is best to route the vented air back into the pipe between the MAF sensor and the turbo to avoid a moment of rich mixture caused by the missing air. For a car that does not have an air flow meter, you can just vent the air to the atmosphere with no ill effects on the mixture.
So any point in afternarket actuator, or at least bov, or adaptor plate ,, at least for sound and or reliability?
Cheers
Now, I have (quite) a few questions, that may or may not be somewhat rhetoric, but haven't seen anything else on the forum that really addresses this (particularly in regards to the turbo setup in the 4c). Also may be for the benefit of some members who are still getting confused, particularly in highlighting, not only the benefits of mods, but the difference between what a
-Turbo waste gate/actuator is, and what a
Diverter blow off valve is, and
-Whether both are internally recirculating, or
-"Dumped/vented to atmosphere,
Both wastegate and bloff off valve in our cases are recirculating are they not?
-Any point in adding aftermarket mechanical or electronic boost controllers?
i.e what are the
benefits in boost/power?
benefits in better quality/longevity over OEM plastic parts and weak springs/components? For an aftrmarket blow off valve,, i like more sound i.e
the benefit of controlling the sound of how loud the blow off valve vents to atmosphere?
and
What sounds do we hear from the engine,?? Is the distinctive "barp" sound between shifts coming from the waste gate recirculating (or venting ) exhaust to control turbo boost, or is it the diverter/blow off valve recirculating (or once again venting to atmosphere) the pressurized intake air?
Now a lot of people are confused with the difference between a waste gate and a blow off valve. They are two complete different things as we may or may not know..
WG: Regulates pressure on the exhaust side i.e turbo boost
BOV: Regulates pressure on the intake side. Stops excessive flow back pressure on the turbo vanes after the throttle plate close
As far as i know, This limit is controlled by the waste gate , which "sees" the intake pressure and opens up when the limit is reached to vent off or bypass the exhaust gas around the turbo (vented to the catalytic converter or atmosphere), thus preventing it from spinning faster and creating more boost. It doesn't vent out the intake air.
Hence , the waste gate controls the maximum boost pressure (limited by how much your engine can take/ turbo rev limit etc). Changing how much your waste gate "sees" can allow you to increase this limit (increase maximum boost)
A blow off valve, on the other hand, lies on the intake side and is meant to open up when the throttle is closed (by sensing engine vacuum). This vents out the pressurized intake air to the atmosphere. This is required because as you rev the engine up , the turbo spools up as well. The instant the throttle is let go, the turbo continues to create boost which now has no where to go. This causes the turbo to quickly spool down which creates a lot of impulsive stress on the turbo. Consequently , the turbo (now having spooled down) will take time to spool up when the throttle is re-applied.
Hence the blow-off valve protects your turbo by allow it to continue to spin (rotational inertia) and vent out the un-required air, when the throttle is closed. A consequence of which is reduced turbo lag eg. between gear shifts etc. Installing high flow blow off valves may improve turbo spool performance to a perceivable extent.
Poor bov design chirping
like when the throttle closes during a shift. When a BOV is vented to atmosphere, it produces a distinctive hissing sound, and when a BOV isn’t used or is of insufficient size, the compressor surges and makes a chirping or rattling sound. Compressor surge can put stress on the compressor and its bearings, shortening its life. I hear this chirpping all the time, meaning the oem blow off valve, being plastic is not that good...i.e plastic
Quote,
For cars with metered air (a flapper valve or hot wire MAF sensor), it is best to route the vented air back into the pipe between the MAF sensor and the turbo to avoid a moment of rich mixture caused by the missing air. For a car that does not have an air flow meter, you can just vent the air to the atmosphere with no ill effects on the mixture.
So any point in afternarket actuator, or at least bov, or adaptor plate ,, at least for sound and or reliability?
Cheers