The External Wastegate
External Wastegates are one of the most commonly misunderstood pieces of the turbocharging puzzle. These devices are responsible for regulating boost by allowing exhaust gasses to bypass the turbine of the turbocharger, making sure the compressor does not spin too quickly and produce too much boost.
However, there are a lot of myths and misconceptions floating around, so we picked five of our favourites that we have heard, and let our engineers bust the myths.
1. You don’t need a wastegate.
Well, if your aim is to destroy your turbo and/or blow up your engine, then yes, you don’t need a wastegate! While in theory, you could run a turbo system without a wastegate by carefully choosing a turbo that will only reach its maximum turbine speed and desired boost pressure at the engine’s max RPM, it’s really not practical in the real world.
2. The more powerful the engine, the bigger wastegate I need.
False. A wastegate is possibly the only component in your whole engine package that can actually be made smaller as you increase your boost/horsepower output – in certain circumstances. An external wastegate is used to drive exhaust gasses away from the turbocharger to regulate turbine speeds and therefore boost pressure. Selecting the correct wastegate size depends on the amount of exhaust to be bypassed, the desired boost pressure, and the amount of exhaust gas the turbo requires to reach that boost pressure. An engine that produces a lot of exhaust gas but running low levels of boost will require lots of exhaust to be diverted away from it by the wastegate, requiring a bigger wastegate. Higher boost levels will require less exhaust to be diverted away from the turbine, so the wastegate can be smaller.
3. External Wastegates don’t operate in high temperatures.
External wastegates are usually mounted at the hottest part of the exhaust. It’s the place where all the exhaust gases meet, creating extra heat.
A wastegate should always be mounted somewhere it can cool off, rather than being choked with hot air, surrounded by hot exhaust and engine with no airflow. Access to fresh air helps keep the wastegate at a safe operating temperature, extending its life and reducing the risk of failure.
Even so, Turbosmart’s wastegates are designed and tested to cope with extreme heat. Their carefully selected elastomer, materials and tolerances ensure that they are up to the job and can handle the heat of the most serious applications.