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Discussion Starter #1
I am looking to buy a '93 dodge CTD 4 speed automatic. It has the pump turned up a bit, a cold air intake, and muffler delete. When accelerating hard I left off, and I get compressor surge for 1-2 seconds. Why does this happen.
 

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The turbo compresses air. When you let off the drive presure in the exaust manifold go's down. The presure of the air overcomes the drive presure and the air pushes back into the intake, spinning the turbo backwards.
 

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You will have to learn how to keep that from happening, slowly let off of the throttle instead of going WOT to idle position. You beat on it too much and do that and you take a chance on twisting that turbine shaft smooth off.
 

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Discussion Starter #4
ok thanks, I understand the principle of what is happening, just now sure why its happening with a almost stock truck.
 

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This is actually turbo "bark"; compressor surge is defined as the following:

What is compressor surge?
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.
 
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