Where is the wastegate

Wastegate valve in the turbine housing outlet of a Garrett GTP38 turbocharger Traditionally with exceptions , a variable geometry turbocharger VGT does not require the use of a wastegate as boost is controlled perpetually by the position of the vanes in the turbine housing.

Recall that a VGT physically adjusts the effective size of the turbine housing by increasing or decreasing the pressures of exhaust gases acting on the turbine wheel. Rather than divert exhaust gases around the turbine wheel a VGT simply opens the vanes, simulating a similar effect as a wastegate. As the vanes close, exhaust energy acting on the turbine wheel increases.

This range of motion is used to provide desirable turbocharger response while controlling peak boost pressure and performance characteristics under all conditions. An alternative to a wastegate is a blow-off valve. A blow-off valve is a mechanical valve mounted between the turbocharger compressor outlet and intake manifold can be mounted anywhere in the intake system on the pressure side of the turbo. Excessive boost pressure is released to the atmosphere.

Once the manifold pressure drops below the max setting, the valve defaults to the closed position. Unlike a wastegate, a blow-off valve is traditionally used as a failsafe device and not a means of consistently controlling manifold pressure. A question as old as time, and actually has a pretty simple answer. An internal wastegate resides directly inside the turbine housing. It's a built-in wastegate actuator.

It's easier to manage, with less piping, meaning a more compact wastegate. Internal wastegates divert the exhaust flow back into the exhaust system. Internal wastegates are found on most stock vehicles.

An external wastegate sits outside of the turbine housing and is its own separate, self-contained system. It requires a special turbine housing that allows a connection to the external wastegate. External wastegates are usually installed aftermarket, and are used for much more precise boost level control, and are usually found in high-power engines. We do it right. To look at Banks diesel power systems that feature the Big Head actuator, click here ». You must be logged in to post a comment.

Banks Power Tech Articles. Last month, we launched Turbo tech — a series of posts designed to provide some basic information about different turbocharging components. By controlling and limiting the speed of the turbine, the wastegate regulates the boost pressure provided by the turbocharger.

By preventing the boost pressure from rising indefinitely, the wastegate protects the turbocharger and the engine from damage. In most cases, a wastegate is a relatively simple valve, controlled by a pressure actuator linked to the boost pressure of the turbo.

The wastegate is held shut by a spring inside the actuator, but when the boost pressure exceeds the pre-set maximum, it compresses this spring, progressively opening the wastegate. This allows the exhaust gases through, so that they bypass the turbine, regulating its speed. Most turbochargers are fitted with internal wastegates, with a valve that is built into the turbine housing itself.

This valve is controlled by an actuator, which consists of a spring and a sealed chamber, and this chamber is linked to boost pressure usually via a pressure source found on the compressor cover of the turbocharger. Usually reserved for higher power engines fitted to performance and race vehicles, external wastegates are separate, self-contained mechanisms that are usually fitted to the exhaust manifold or header.