How Does a Wastegate Work? (Explained)

✔ This article has been fact checked.

A wastegate is a valve that is used to control the amount of exhaust gases that flow through the turbine in a turbocharged engine. It helps to regulate the boost pressure of the engine and prevent it from overboosting.

The wastegate regulates the flow of exhaust gases through the turbocharger by opening and closing at a predetermined boost pressure. When the boost pressure becomes too high, the wastegate opens to release excess exhaust gases.

In this article, we will explore how a wastegate works and the various types that are available.

Table of Contents:

• What a Wastegate Is

• How They Work

• Open or Closed

• Types

• Conclusion

What Is a Wastegate?

A wastegate is a valve that is typically mounted on the exhaust manifold or the exhaust pipe of a turbocharged engine. It is designed to regulate the flow of exhaust gases through the turbine of the turbocharger.

The wastegate is connected to the turbocharger by a rod or a hydraulic actuator.

The wastegate is essential for controlling the boost pressure of the engine, as it prevents the turbocharger from spinning too fast and overboosting the engine. If the turbocharger spins too fast, it can cause damage to the engine and lead to reduced performance.

How a Wastegate Works

The wastegate is controlled by a wastegate spring that is connected to the valve. The spring is designed to keep the valve closed at low engine speeds, and as the engine speed increases, the spring expands and begins to open the valve.

Below is the process of how a wastegate regulate boost pressure.

1. Throttle is applied and the wastegate is in its closed position allowing all exhaust gas to flow through the turbocharger

2. The turbo builds boost pressure as the rpms increase and the exhaust gas increases in flow

3. Boost pressure reaches a pre-determined level and the wastegate opens allowing a certain percentage of exhaust gas to bypass the turbine

4. The actuator regulates the position of the wastegate valve to maintain the set boost pressure level

The wastegate also has a diaphragm or a piston that is connected to the actuator. The actuator is controlled by a boost pressure sensor, which measures the boost pressure in the engine.

When the boost pressure reaches a certain level, the actuator begins to open the wastegate, allowing excess exhaust gases to bypass the turbine and flow directly out of the exhaust system.

The wastegate is designed to open and close at a predetermined boost pressure. This helps to maintain a consistent boost pressure and prevent the engine from overboosting.

A diagram showing how a wastegate works.

Are Wastegates Normally Open or Closed?

Wastegates are normally closed at low engine speeds and open at higher engine speeds. This allows the turbocharger to build boost pressure as the engine speed increases.

However, if the boost pressure becomes too high, the wastegate will open to release excess exhaust gases and prevent the engine from overboosting.

Different Types of Wastegate

There are two main types of wastegates.

1. External

2. Internal

External

External wastegates are mounted externally on the exhaust manifold or exhaust pipe, while internal wastegates are built into the turbocharger itself.

External wastegates are typically easier to maintain, as they can be accessed and serviced without having to disassemble the turbocharger. They also allow for more precise boost control, as they can be easily fine-tuned by adjusting the spring tension.

Internal

Internal wastegates are more compact and require less space, but they are more difficult to access and maintain. They are typically used in smaller turbocharged engines, where space is at a premium.

Modern vehicles usually use an internal wastegate from the factory while external wastegates are more commonly used in aftermarket turbocharger systems.

> Read more about internal vs external wastegates

Conclusion

In conclusion, a wastegate is a crucial component of a turbocharged engine that helps to regulate the boost pressure and prevent the engine from overboosting.

A wastegate works by opening and closing at a predetermined boost pressure to release excess exhaust gases and maintain a consistent boost pressure. There are two main types of wastegates; external and internal, each with their own unique characteristics and benefits.

Sources