Internal vs. External wastegate: What Are The Differences?

The difference between Internal and External wastegate is that the external wastegate is preferable to the internal one when it comes to higher performances, because of its larger inlets and outlets which successfully manage higher boost pressure and protect the engine. 

A  wastegate, as you may know, is a valve that controls the flow of exhaust gases. This system is used by turbocharged engines. Good wastegate prevents the turbine from spinning too fast. By doing that they save the engine from any damage.  There are two types of wastegates: internal and external. 

All turbocharged engines have built-in internal wastegates. Mainly, internal wastegates are designed to stock the boost levels of a turbocharger. If you want extraordinary performance while saving the engine from damages, you need an external wastegate. By reading this internal vs. external wastegate comparison you will understand why. 

Internal Vs. External Wastegate In A Table

ComparisonInternal WastegateExternal Wastegate
FunctionControlling exhaust gases into the turbo and stock boostControlling exhaust gases and the boost
TypeOEM componentAftermarket parts
PerformanceAverageHigher performance
Pressure handling CapabilityLimitedHigher capability
Fuel EconomyEconomically SoundNeed more fuel than internal wastegates
InstallationSimpleTime-consuming
UsageOrdinary automobilesRacing vehicles and trucks
EmissionsEnvironment friendlyHamper environment
PriceInexpensiveA bit expensive

What is an Internal Wastegate?

Internal Wastegate

An internal wastegate is an integral bypass valve and passage within the turbocharge housing which allows excess exhaust pressure to divert the turbine into the downstream exhaust. The majority of turbocharged engines have an internal wastegate. OEM wastegates are routed back into the exhaust system. Because of its simple structure, the internal wastegate can handle only a limited amount of pressure. Therefore they are used in simple everyday used vehicles. 

What is an External Wastegate?

External Wastegate

External wastegates are separated actuator which is later fitted into the turbocharger. It follows a self-containing mechanism. An external wastegate controls the boost levels of exhaust gases produced by the turbocharger itself. Some external wastegates are adjustable. In rare cases, it uses a butterfly valve. External wastegates are a viable option for higher-performance vehicles. They are used in tracks and racing vehicles. 

When to install an External Wastegate?

Generally, your turbo system does not require an external wastegate however if you want to stock a power boost you may need one. For this reason, many manufacturers feature an external wastegate design. You need to install an external wastegate for the following reasons:

  • Require a higher functioning engine.
  • Want to an aftermarket turbo.
  • More control over the boost.

Internal Vs. External wastegate: Differences

Size

The size of a wastegate depends on the expectation level of boost and power you want to get from the engine. In the case of turbo engines the smaller the size the more power it has. For this reason, external wastegates are smaller than internal wastegates. 

Performance

External wastegates are ideal for extreme performance, particularly in racing automobiles. With a decent external wastegate, you can compete in dragstrip and rallying. Meanwhile, the internal wastegate is a simple mechanism that is adopted for vehicles that do not require supercharged engines.

Adjustable springs

The amount of boost a turbo can retain is determined by a number of elements, one of which is the spring within the wastegate. The spring in OEM wastegates is sealed, which means they cannot be modified. Internal springs on aftermarket or external wastegates are adjustable and replaceable. They can take high pressure as well. 

Inlet and Outlet

External wastegates have larger inlets and outlets compared to internal wastegates. 

Emissions

In the internal wastegates, all leftover exhaust gases are directed back into the catalytic converter and exhaust system. That is why internal wastegates are environmentally friendly. On the other hand, external wastegates directly vent all the waste gases into the atmosphere. 

Fuel Economy

More power necessitates more fuel energy, so external wastegates demand a larger fuel budget than internal wastegates.

Pros and Cons

Pros

Internal Wastegate External Wastegate
-Simpler and compact installation
-Require little piping
-Environment friendly 
-Developed for the higher performance
-They can adopt extreme pressure quickly
-More reliable 

Cons

Internal Wastegate External Wastegate
-Can deal with limited exhaust gas pressure
-Sometimes impinges maximum performance 
-Time-consuming installation
-Requires more piping 

What do we think?

In our opinion, if you do not have any specific preferences like super boosting or racing then internal wastegates are perfectly enough for your turbo engine. They are very simple, economically sound, and environment friendly. 

Final Words

We learned that turbochargers need exhaust gas to run and there should be a way to control that gas, so mechanics had invented wastegates to control the gas flow as well as the boost. There are two types of wastegates: Internal and External.

The first one is common in almost all turbocharged engines. Internal wastegates are built-in by manufacturers. While external wastegates are separate components that need to be fitted if you require one. They are more capable of handling pressure and boosting power. Racing vehicles require an external wastegate. 

By now we hope that you have gained a clear idea about internal vs. external wastegate and decided whether you need an external one or not.

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