Surge is big boost with small flow, as my rough understanding.
How is the "real" situation?
My turbo has been repaired twice. Each time they told me the compressor wheel should be enlarged. Which I don't know why. The boost was coming on 2600~2700rpm & touched the top on 3000 in stock form. After enlarged twice, now it won't go to the max until 3600~3700. I feel the power band is shifted upward by 800~1000rpm overall.
Since then, I noticed when in 5th gear light boost mild acceleration on motorway, the small opening throttle & boost are fighting with each other. Even the dump valve air flow can be heard. It's boosting & dumping at the same time. What a waste! To avoid stumbling, I have to use the softest spring in my Forge dump valve.
Is this some kind of "surge"? Boost on small flow?
Or, in another situation, when dialing up boost severely, it would be skyroketing in the midrange without related performance output. Turbo is screaming but the engine seems not able to swallow the air untill the rpm comes high enough.
If these are "surge", then adding WI prior to the compressor will make it worse? By this, maybe the trigger point should be higher.
Any thoughts? Or I misunderstand all these?
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