define: surging
 

for some reason, search isn't working - keeps thinking i'm trying to overload it and warns me that i can only search every 20 secs.

In the world of turbos, boost and all that fun stuff, define "surging" and how does it feel/look like to the untrained average joe. Hopefully there's a simple analogy like "pinging" sounds like metal bb's being dropped into a coffee can. Similar to that.

Thanks.