Originally posted by JDEstill
Freed, surge is a lot more than just what happens when the throttle is closed after going WOT. If the compressor is mismatched to the engine it is feeding, you can have surge at part throttle. There's plenty of guys running monster turbos that surge when they are at part throttle, trying to hold 10 psi or so. If their engine at 10 psi boost can't take the minimum amount of air their turbo needs to flow, surge is the result.
John