Wastegate Flutter.

[Husky]

 

Q. What is compressor surge?

A. The surge region, located on the left-hand side of the compressor map (known as the surge line), is an area of flow instability typically caused by compressor inducer stall. The turbo should be sized so that the engine does not operate in the surge range. When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side. Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself. Common conditions that result in compressor surge on turbocharger gasoline engines are:

 

-A compressor bypass valve is not integrated into the intake plumbing between the compressor outlet and throttle body (BOV)

-The outlet plumbing for the bypass valve is too small or restrictive

-The turbo is too big for the application

 

Awesome stuff, good info from a good source.

[Tricky-Ricky]

Ok, so if one were to feel the need to remove their BoV and block that off, what would a noob use to achieve this?

My advice would be don't

It's there for a reason well several really

to prevent damage to the turbo especially if it has ceramic blades as some Celica's and Mr2's had from the factory

to stop the turbo stalling, which will increase lag

and stop over-pressure in the system between the turbo and the throttle body causing potential damage this was caused when the vacuum hose came off my BOV

 

 

if you really want this sound then get an adjustable BOV so you still have some protection

 

 

 

Turbos only have ceramic blades on the exhaust turbine, not the compressor, these are always metal or nylon, neither will be damaged by having no BOV.

 

well since i'm obviously dumb i lifted this straight off Garrett's site but what do they know

 

Q. What is compressor surge?

A. The surge region, located on the left-hand side of the compressor map (known as the surge line), is an area of flow instability typically caused by compressor inducer stall. The turbo should be sized so that the engine does not operate in the surge range. When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side. Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself. Common conditions that result in compressor surge on turbocharger gasoline engines are:

 

-A compressor bypass valve is not integrated into the intake plumbing between the compressor outlet and throttle body (BOV)

-The outlet plumbing for the bypass valve is too small or restrictive

-The turbo is too big for the application

 

 

 

I'll add one more thing, compressor surge is not compressor stall they are two different things..

[andybp]

Ok, so if one were to feel the need to remove their BoV and block that off, what would a noob use to achieve this?

My advice would be don't

It's there for a reason well several really

to prevent damage to the turbo especially if it has ceramic blades as some Celica's and Mr2's had from the factory

to stop the turbo stalling, which will increase lag

and stop over-pressure in the system between the turbo and the throttle body causing potential damage this was caused when the vacuum hose came off my BOV

 

 

if you really want this sound then get an adjustable BOV so you still have some protection

 

 

 

Turbos only have ceramic blades on the exhaust turbine, not the compressor, these are always metal or nylon, neither will be damaged by having no BOV.

 

well since i'm obviously dumb i lifted this straight off Garrett's site but what do they know

 

Q. What is compressor surge?

A. The surge region, located on the left-hand side of the compressor map (known as the surge line), is an area of flow instability typically caused by compressor inducer stall. The turbo should be sized so that the engine does not operate in the surge range. When turbochargers operate in surge for long periods of time, bearing failures may occur. When referencing a compressor map, the surge line is the line bordering the islands on their far left side. Compressor surge is when the air pressure after the compressor is actually higher than what the compressor itself can physically maintain. This condition causes the airflow in the compressor wheel to back up, build pressure, and sometimes stall. In cases of extreme surge, the thrust bearings of the turbo can be destroyed, and will sometimes even lead to mechanical failure of the compressor wheel itself. Common conditions that result in compressor surge on turbocharger gasoline engines are:

 

-A compressor bypass valve is not integrated into the intake plumbing between the compressor outlet and throttle body (BOV)

-The outlet plumbing for the bypass valve is too small or restrictive

-The turbo is too big for the application

 

 

 

I'll add one more thing, compressor surge is not compressor stall they are two different things..

I think your missing the point but whatever (yes I did just whatever you )

[Rock_Steady]

Edited April 22, 2016 by Rock_Steady

[tubbyandy]

Wastegate flutter is a phrase that always winds me up and I blame clarkson who still goes on about it!! We have compressor stall and surge on our gas turbine jets engines and it's sounds like a much larger banging version. I can kind of see how people could hear a noise from valve cavitation but essentially a wastegate is a spring and a valve so unless it's opening and closing very fast it'll never come from there.

 

As mentioned it's the air moving backwards through the compressor stage. Also surge and stall may not be exactly the same thing but they usually come together. Surge is where the air coming in can't be evacuated or taken into the engine fast enough and it backs up. This will usually lead to it coming back through the inlet with the 'flutter' and stalling the compressor. Stall itself can be the wheel physically going but can also be an inefficiency of each blade to do its job