# Just for observation purposes - boost onset compressor surge



## Eco (May 13, 2011)

My wife had been complaining to me about some ticking she heard with a lot of throttle going up a steep hill.

Naturally I assumed it was knock because we use 87 but with all of the modern ecu controlls I couldn't imagine that being the case. She said it happens to her infrequently so I figured no biggy - we have a LOT of hills around us, very windy steep hill so it's tough to even get momentum going up them...

It finally happen to me last night, but with 93 in the tank...

Turns out it's compressor surge, and the tack tack tack sound is the internal bypass valve rythmically opening and slamming shut. The valve did it's job it didn't actually cause any audible compressor surge, but I could hear what it was.

Steep hill, high gear, AC on 93 in the tank, low RPM it was chugging, then tack tack tack tack tack tack tack, very rythmically.

So, there ya have it, you can generate boost onset compressor surge in this car, that my friends is a very difficult thing to achieve with such a small motor at a low RPM.

It won't hurt anything, but I'll bet some of you can cause this to happen interesting at how well that internal bypass works.


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