Even if you are not a car enthusiast, you are familiar with the word “turbo.”
Often incorrectly used to describe fast, enhanced, or tuned engines, a turbocharger is actually a component used to increase the airflow entering an engine to produce more power with the same displacement. Turbocharged engines originated in the early 1960s but became standard of the industry around the 1980s. Today, we are experiencing a second wave of turbo popularity since they provide modern downsized engines with enough power without sacrificing fuel efficiency and environmental standards. Not to mention that turbochargers are the favorite add-on for millions of power-hungry fans wanting to make their car go faster.
But, not many people know how a turbo actually works and the specific purpose of the wastegate valve. This article will cover everything you need to know about this vital part of most turbocharger systems from what is a wastegate and what it does to the different types and how to adjust one.
What is a Wastegate, and What Does it Do?
The turbocharger is a forced induction device that uses exhaust gasses to power the turbine wheel, which compresses air to build up pressure and blow a more significant volume of air into the engine, creating more horsepower and torque. However, it often happens that the pressure towards the turbine exceeds the maximum boost rating of the component, and this is where the wastegate comes in. The wastegate valve regulates the percentage of exhaust gasses being feed into the turbine side of the turbo, effectively controlling the maximum pressure the turbocharger can create. Once the max pressure is reached, the wastegate will divert, or “waste” a certain portion of the gasses by bypassing the turbo into the exhaust, further down the line.
Different Types of Wastegate
There are two distinctive types of wastegate valves according to the installation location. The first one is an internal wastegate, which is mounted as an integral part of the turbocharger installation. Those types are part of stock OEM turbocharging systems commonly found on most modern forced-induction engines. Internal wastegates are noticeably quieter and dump the excessive gasses back into the exhaust system. The real main drawback of internal setups is the fact that they are not as precise and easily adjustable as external ones. Internal wastegates are most frequently used on stock or lower pressure turbocharging system.
As you can guess, an external wastegate is a separate valve mounted on the turbocharger manifold. It can be found as a common aftermarket addition to non-wastegate turbochargers or professionally built turbocharger setups designed for high power engines. External wastegates are often considered as a better option since they can release a higher volume of gasses, are more precise, and can be easily adjusted if needed.
The basic operating principle is pretty much the same in internal and external models. One another important point with external wastegates is the fact that they are easier to replace if they go bad. A faulty internal wastegate will often require the turbocharger to be rebuilt or replaced.
See also: What is a Blow-Off Valve? | Tuning 101
Most Common Turbo Wastegate Problems
Even though a wastegate is a relatively simple device, after all, it’s nothing more than a mechanical valve, it has a crucial role in the proper functioning of turbocharged engines, stock or tuned. That is why it is essential to recognize common wastegate problems when they occur.
- No boost during acceleration – If the wastegate was to be stuck open, a larger than normal amount of gasses would be diverted from the turbo, preventing it from building pressure. The pressure in the turbocharger manifold will not be sufficient to compress air and produce power, which will result in poor acceleration, jerks, and sometimes misfires.
- Inconsistent boost pressure – Most turbocharged cars have boost meters, which show exactly how much boost the turbo is producing. If the pressure varies and boost is not generated under the acceleration, the problem could be the wastegate.
- Check engine light – Even though the check engine light turns on for pretty much anything when you notice it, it is wise to check the codes for a wastegate malfunction. If you do it on time, you can often prevent other collateral damages to various intake system components.
How to Adjust a Turbo Wastegate
To increase the boost pressure on a turbocharging system, you can often adjust the wastegate opening threshold. Not all wastegates are adjustable, but most of them are, at least, to some extent. Aftermarket turbo kits using external wastegates will usually have a broader range of adjustments. Even stock wastegates can be slightly adjusted up or down.
In most cases, with diaphragm-operated wastegates, you can usually screw down or up a nut on the side of the wastegate, increasing or reducing the travel of the activator shaft, effectively controlling when and how much the valve opens.
Other wastegates, especially on high-performance setups, are adjusted via an actuator, a device that acts as a switch and actually opens the wastegate to release the manifold pressure. Depending on the type, they can be adjusted mechanically, electrically, or electronically.
However, always keep in mind that more boost will put more strain on the whole system, which subsequently can result in significant failure of the manifold, seals, gasket, bearings, and even the turbine itself. In other cases, the vehicle may use sensors to monitor the system’s pressure and might shut down either the injection or the ignition system to prevent significant damage to occur.
For example, in older Mazdaspeed 6, the stock pressure setting was 8psi. And any car enthusiasts looking inside the engine bay could quickly notice that the wastegate still had a lot of room to go up on the adjustment screw. However, once the owner tried to increase the pressure, he would quickly realize that the vehicle would start to cut -off the ingestion as soon as the system passed over 10psi.
In that case, there’s many little tricks you can use to bypass these setting, but that’s a whole other story…