Searched:Compressor stall/define/describe/solution

[sweet97]

What does comopressor stall feel like? What causes it? What are common fixes? I have a dsmchip with fuel cut removed but at high boost(25+) and high rpm's(6500+) I can get what is like A "MINI" FUEL CUT. I BELIEVE IT IS A LACK OF FUEL SO I AM REPLACING THE FILTER TO RAIL LINE WITH -6AN FITTINGS AND HOSE. Sorry for the caps! Could what I describe be compressor stall? Thanks, Mark

 

[99gst_racer]

Compressor stall is a term used in the aviation world. It's something they have to take into affect because of constant changing variables that can effect the compressor.

What makes you think you are suffering from compressor stall and not simply compressor surge?

Compressor stall occurs whenever the airflow in the compressor becomes unstable. Instability occurs when the effective angle of attack of one or more compressor blades is exceeded (just like surge). Because of its destructive nature, compressor stall is one of the most critical concerns in axial flow compressor design (just like surge).

The difference between the two is that surge is the term used when it affects the entire system. Stall is basically surge that affects one individual compressor blade.

Being that an airplanes compressor is several hundred times larger than our turbo's compressor, it is possible that they can compressor surge to only one blade, hence compressor stall. That does not really apply to our small compressors/turbos. When the entire compressor "stalls" it is called compressor surge and that is what we get.

 

[sweet97]

Paul I am trying to diagnose the problem I am having, thus the need for definitions. When running hoigh boost(25+PSI) and high rpm's(6500+) I get a "buck", "burp", not a backfire or fuel cut but something similar. IDC one time I watched the gauges was 91%, A/F was 11.xx:1, timing was 10*. Don't jump on the timing as KEYDIVER has extended maps in my chip because of the high boost on pump. Motor will run 30PSI on pump, no knock with tuning. I tried a chip with mopre timing and same scenario. I am upgrading the filter to rail fuel line as I may be running short on fuel volume, the banjo on the filter is rather restrictive. A more likely culprit is my wastegate actuator. I run a Holset and there is minimal preload on the arm. I have the turnbuckle all the way threaded onto the actuator arm. Boost could be blowing open the wastegate momentarily. Now I have a couple of things to work with. Thanks, Mark

 

[99gst_racer]

Paul I am trying to diagnose the problem I am having, thus the need for definitions. When running hoigh boost(25+PSI) and high rpm's(6500+) I get a "buck", "burp", not a backfire or fuel cut but something similar. IDC one time I watched the gauges was 91%, A/F was 11.xx:. I am upgrading the filter to rail fuel line as I may be running short on fuel volume, the banjo on the filter is rather restrictive.

If you run short on fuel enough to make the car buck, your AFR would show it.

A more likely culprit is my wastegate actuator. I run a Holset and there is minimal preload on the arm. I have the turnbuckle all the way threaded onto the actuator arm. Boost could be blowing open the wastegate momentarily.

If the wastegate flapper was blown open at an incorrect time, you would feel power loss, but it should not feel like a "bucking" feeling.


Are you sure you aren't experiencing basic compressor surge?

 

[sweet97]

I got a good description on surge/stall that included my condition in the definition of surge/stall. It listed one thing it can cause is a "loud bang", that's my "buck".
Now it seems the condition has been diagnosed.
Solution?:
I have a Buschur P&P head w/272's. However I am still on the stock intake. I have a JM SMIM to go on this winter. Getting the TB rebuilt and bored a bit which will increase it's flow by 9-10%. Upgrading the lower IC piping also.
Can the restrictive TB, intake and IC piping be causing this? Thanks, mark

 

[Steve93Talon]

I just noticed that Bullseye doesn't have the HX35/40 on their site anymore. They only offer the HX35 and HX40. I wonder if they were experiencing any surge problems with the 35/40 due to the mixing of wheels. Have you called them and talked to Dave about this yet?

 

[sweet97]

The one time I spoke to him about the hybrid he said there were not too many out there because of cost, they were the same if not more than the HX-40. What about my proposed winter mods, intake, IC piping and TB bore. I understand surge happening because the air backs up? Mark

 

[pneumo]

Surge happens whe the turbo spools up too quick, such as when you have a large compressor wheel paired with a small turbine wheel and/or small turbine housing.

Another cause could be a poorly adjuste BOV that can't hold high boost.

 

[sweet97]

I do have a Hybrid turbo but the turbine wheel is larger than a stage 5 I believe. I could try a stronger spring in the TIAL as I have one step higher here. Mark