The turbocharger, controlled by the waste-gate valve, limits pressure even at low rpm, optimising torque and fuel consumption. The limitation of pressure is essential for mechanical protection of the engine and the turbo.
The waste-gate system permits turbo boost pressure to be kept constant, whilst allowing gradual pressure relief in certain conditions. It is this exhaust gas pressure which, having reached predetermined levels, opens a valve in the exhaust manifold. This permits by-pass of the gases before they impact on the turbo.
