[Company Logo Image]     Performance Trends Inc

    Producing Quality Computer Tools for Racers and Engine Builders since 1986






Compressor Map

Compressor Map is a graph that shows the performance of a Turbo or Supercharger compressor by showing the speed, efficiency, flow rate, and boost pressure.

(click on image to enlarge it)

Operating characteristics

The compressor operating behavior is defined by a map displaying the association between pressure ratio and volume or mass flow rate. The useable section of the map relating to centrifugal compressors is limited by the surge and choke lines and the maximum permissible compressor speed.

Surge line

The map is limited on the left by the surge line. This is the limitation of the air flow at the compressor inlet. If the pressure ratio is too high and the volume flow is too small, the air no longer sticks to the suction side of the blades, then the discharge process is interrupted. The air flow stops going through the compressor and is reversed until the pressure is stabilized and the positive volume flow rate is reached again, then the pressure builds up again and the cycle repeats. This flow instability creates a pulsation and the resulting noise is known as "surging".

Choke line

The cross section of the compressor inlet is normally the limitation of the maximum centrifugal compressor volume flow rate. When the flow at the inlet reaches it's maximum velocity the flow rate can no longer be increased. The choke line is the rapidly descending line on the right of the compressor map.

Programs that can import a Compressor Map:

Our Engine Analyzer Pro v3.9 program will import a few points off of some Compressor Maps along with Our Engine Analyzer v3.2 and Engine Analyzer Plus v3.2. And then use those points to give you an accurate simulation of the turbo or super charger you may want to use.