Every-now-and-then we run into an issue with an internal wastegate on the turbos we work on. Wastegates are the valves that release excess pressure when you aren’t pushing on your turbo. The pressure builds when you spool up the turbo but when you shift or decelerate that pressure needs to go somewhere or it will blowback on the turbo… which is a really bad thing to have happen.
So, there are these internal wastegates that are inside a turbo. A little pressure switch flips open a door for the release with a little whistle sound. Not usually a problem but when we start working on turbo cars with 250hp+ we stop losing control of the boost. For instance, the last car we had with this problem we wanted to have the boost around 10PSI, but we couldn’t get it below 20PSI. All because the door on the wastegate is smaller than we need and the boost release was like having a hairdryer blowing through a coffee straw, there will always be a high pressure.
Internal wastegates are really great--they are less operating parts, smaller in size, they can be ported a bit better than stock, and cheaper because they’re usually already built into the turbo. But when you are thinking of high performance or race level engines, you need to start thinking about having a larger diameter door for the release. You can only bore out the door internally so far before you’re cutting into the integrity of the turbo.
What we do is weld the door shut (make it look like it was never there) and install an external wastegate on the exhaust header itself. What we see is complete control over pressures, allowing us to increase the efficiency of the turbo and even add to the strength of the motor.
Ultimately, internal wastegates are the way to go on the daily-turbo-driver, but when you’re thinking of going big with the engine always plan on having an external wastegate built into the exhaust header.
If you have any questions, as always, give us a call or email us - Contact Page
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