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Where to Position an External Wastegate (Explained)

Updated: Jan 8

If you install an external wastegate to your turbocharged engine, you have full control as to where you position the wastegate. There are optimal and less-than-optimal positions to put one.


The best place to install a wastegate is as close to the turbine housing as possible. The next best position is at or just after the exhaust collector. Ensure that there is a clear path for the flow of gases into the wastegate.


In this article, we'll discuss the best and worst places and ways to mount and position an external wastegate.

 

Table of Contents:


an external wastegate

What Is an External Wastegate?

The wastegate is an exhaust bypass valve that is used to regulate the flow of exhaust gases in a turbocharged engine. It is designed to prevent the turbo from producing too much boost by allowing some to bypass the turbine of the turbo.


There are two types of wastegate, they both have the same function but have different properties and their own unique pros and cons.


  • Internal wastegate

  • External wastegate


An internal wastegate is built into the turbocharger itself. An external wastegate is a separate component from the turbocharger and has much more customisability, it allows more precise control over boost pressures and is common on big power modified engines.


Where to Position an External Wastegate

The best position for an external wastegate is one that allows for good flow into the wastegate and minimises the length of the exhaust pipes.


It is important to note that the positioning of the wastegate can have a significant impact on the performance of the turbo system. If the wastegate is not properly positioned, it can cause problems with boost control.


Optimal Position: Close to the Turbine Housing

One of the best places to position an external wastegate is as close to the turbine housing as possible. This allows for the shortest possible exhaust pipes, which can improve the overall efficiency of the turbo system.


The wastegate should also be positioned in a manner that allows for good flow into the wastegate itself. If the wastegate is not properly positioned, it may not function properly and could potentially cause problems with the turbo system (such as over-boosting).


Next Best Location: Near the Exhaust Collector

If it is not possible to position the wastegate close to the turbine housing, the next best location is at or just after the exhaust collector.


This allows for the exhaust gases to flow freely into the wastegate and minimises the risk of any restrictions or bottlenecks in the exhaust system.


Therefore, it is important to carefully consider the location of the wastegate when installing a turbo system.


What Angle to Mount the Wastegate?

The angle of the external wastegate is just as important as the position it's mounted. The proper angle at which to mount an external wastegate is an important consideration when installing a turbocharged engine.


  • You should mount the wastegate inlet pipe at a greater than 90° angle from the primary exhaust pipe.

  • It shouldn't be any less than a 90° angle.

  • The most optimal angle to mount the wastegate is in a "teardrop" or symmetrical shape.


If the wastegate is not mounted at the optimal position or angle, it can lead to problems such as overboosting or poor exhaust gas flow.


a diagram showing the best angle to mount the wastegate inlet pipe

Wastegate Inlet Pipe Should Be Greater Than a 90° Angle

The ideal position for maximum flow to the wastegate is to have its inlet tube mounted at as shallow an angle (greater than 90 degrees) as possible from the primary exhaust tubes that feed the turbine.


Ensure the angle of the wastegate inlet pipe is following the flow of exhaust gas, allowing easy exhaust gas entry into the wastegate.


A shallow angle mounting is sometimes referred to as "teardrop" mounting, as a shallow angle cut creates a teardrop shaped weld where the wastegate tube is attached to the primary exhaust pipe.

This allows the exhaust gas to flow smoothly and uninterrupted to the wastegate, ensuring that it is able to properly control boost pressure.


Divided or Symmetrical Wastegate Exhaust Pipe Setup

A divided or symmetrical setup, where the primary splits exhaust gas flow down the middle between the wastegate and turbine, is also an efficient design. This is often seen on professional drag cars, as it allows for precise control of boost pressure.


However, due to space constraints in a typical street car engine bay, it is more common and oftentimes more feasible to use a smaller-diameter inlet pipe feeding the wastegate at a shallow "teardrop" angle.


Wastegate Shouldn’t Be Less Than a 90° Angle

Mounting the wastegate at a 90-degree angle or less is less efficient. When the wastegate tube is mounted at a 90-degree angle, the exhaust gas does not follow a natural path to the gate, which can lead to overboosting or poor exhaust gas flow.


While mounting the wastegate tube at less than a 90-degree angle creates even less efficient exhaust gas flow, further hindering the wastegate's ability to properly control boost pressure.


Conclusion