Wastegate

A wastegate is a valve that controls the flow of exhaust gases to the turbine wheel in a turbocharged engine system.

Diversion of exhaust gases regulates the turbine speed, which in turn regulates the rotating speed of the compressor. The primary function of the wastegate is to regulate the maximum boost pressure in turbocharger systems, to protect the engine and the turbocharger. One advantage of installing a remote mount wastegate to a free-float (or non-wastegate) turbo includes an allowance for a smaller area over radius (A/R) turbine housing, resulting in less lag time before the turbo begins to spool and create boost. One of the earliest usage of a modern wastegate was in the Saab 99 Turbo 1978, presented in 1977.