Waste Not Want Not: Should You Choose An Internal Or External Wastegate For Your Turbocharger?

If you own a vehicle that came fitted with a turbocharged engine, it's more than likely that your turbo is already well suited to the task in hand. However, once you start modifying your car's engine to achieve more power and performance, modifications and certain turbo accessories may be required to ensure your turbo can handle the extra workload, and fitting an aftermarket wastegate to your turbo can be an easy and effective way to increase its efficiency.

What are wastegates?

Put simply, a wastegate is a valve through which excess exhaust gases are released when then air pressure inside your turbocharger becomes too high. As well as benefiting your vehicle's performance, wastegates also prevent overheating and over-pressurisation problems, which can become perennial (and expensive) problems if you upgrade your engine without upgrading your turbocharger alongside it.

However, wastegates come in two distinct varieties, known as internal and external wastegates. Though very similar in form, they are quite different in function, and each has its own advantages and disadvantages to deal with. You should therefore consider your needs carefully before deciding which wastegate variety is best for your turbo.

What are the pros and cons of internal wastegates?

Internal wastegates are integrated directly into the housing of your turbocharger, and automatically release excess exhaust gases once your turbo's internal pressure reaches a certain level. They are a common sight on stock turbochargers, but can be replaced with more efficient aftermarket models if you are seeking to improve performance.

The advantages of these wastegates are numerous; They are relatively compact and require minimal extra piping to be installed, making them ideal for vehicles with limited engine bay space. Their simplicity also means they tend to both extremely reliable and highly affordable. However, when compared to external wastegates, they fall short in terms of providing raw power, so drivers dedicated to eking out every last horsepower from their engine may wish to steer clear.

What are the pros and cons of external wastegates?

As the name would suggest, external wastegates are entirely self-contained units that are not fitted to the turbocharger itself; instead, they are fitted to your vehicle's exhaust manifold. This position allows them to release excess gases further down the exhaust system, rather than directly into the atmosphere like internal wastegates.

This unique functionality generally makes for substantial power upgrades, and even a modestly priced external wastegate can provide significantly more power than an internal wastegate. However, this power comes at a price; they are most difficult and expensive to fit, and the added complexity makes them a little more difficult to maintain. They can also substantially increase engine noise, although whether this is an advantage or a disadvantage is largely a matter of personal preference.