How much of a problem IS compressor surge?

[Mosaic]

Hi all:

 

I've been looking at an engineering solution for low rpm compressor surge. This happens when the turbo is operating on the far left of the compressor map rather than in the middle.

 

Usually upgrading a compressor wheel size,housing, or even replacing a factory BOV with a no-leak aftermarket unit can trigger this. Oversizing a turbo is also a cause.

 

Now the whole issue comes down to too much CFM airflow for the motor to displace at lower rpm's. But, the motor does quite well at consuming the cfm at higher rpm's. This problem is a matter of air volume per sec as opposed to air pressure.

 

The proposed solution which I present for discussion here is:

 

The use of a servo controlled butterfly valve to vent (MAP) or bypass (MAF) excess CFM in the RPM range that causes the compressor surge, thus allowing boost to be built properly and MAF fueling to be based on non turbulent air flow. When the motor passes the rpm range that induces the surge, the butterfly closes thus maximising turbo performance and power/torque delivery. The solution requires user input when tuning the vehicle or fuzzy learning logic to be self taught.

[Tony D]

Read "What is Compressor Surge" sticky above. A control scenario supposeldy exists to vent this flow and allow operation at higher pressures/lower flows.

 

You have made a partial mistatement, it is NOT simply a matter of flow, it is a matter of flow at a specific pressure. Surge is ALWAYS a fuction of flow at a given pressure. It is explained in the aforementioned post.

Edited June 3, 2010 by Tony D