11 Compressor surge

Turbo cars make great noises, especially when they’re tuned. It’s all part of the fun! Some sounds, however, can signal problems. A ‘flutter’ or ‘turkey gobble’ sound (sometimes wrongly referred to as ‘wastegate chatter’) is a case in point. This noise is the sound of compressor surge, which happens when the turbo is delivering more air than the engine can inhale. Essentially, the air backs up in the system and eventually tries to force its way back through the turbo. The air then hits the still spinning compressor wheel blades, resulting in the noise. This may sound pretty cool to the untrained ear, but the added pressure on your turbo will cause accelerated bearing wear. You have been warned.

How to prevent it

Eliminating compressor surge can be achieved by fitting a blow-off valve suited to the amount of additional boost that needs to be released. If you’re still experiencing surge when the engine is at wide open throttle (WOT) – when any blow-off valve would be shut and not flowing any air– you need to consider other aspects of your Porsche’s forced induction system, including turbo sizing, wastegate(s), mapping and actuator function.