How does one correctly preload a turbocharger’s waste actuator?
We get asked this question often, so here is a little guide on how to correctly preload a turbo’s wastegate actuator. In general, you adjust the preload according to the pressure of the spring that is in the actuator. Most aftermarket turbos are set to 1.0 bar. Actuators can be adjusted up or down ~+/- 0.1 bar of their spring pressure. Our turbos come preloaded with 0.9-1.2 bar depending on the application.
Our adjustable actuators can take a number of different springs to achieve a wide range of preloads. We also sell them separately as a retrofit for people with stock or other brands of turbos. Extra springs if you already have our actuator.
1. Attach the actuator to the compressor housing.
2. Attach the actuator to the arm of the turbine housing’s flapper arm. Note: do not insert the cotter pin yet to the flapper arm.
3. Attach a boost source to the barb on the waste gate actuator. Pictured below is a custom made apparatus that connects to an air compressor. We also sometimes use a reversible vacuum pump (one that can be reversed to make pressure as well as vacuum) and use that to apply the target pressure.
4. Apply the target pressure which should match the spring that is inside. Then, apply 0.1 bar of pressure more than the target.
5. Check the flapper’s gap. It should be open around 0.10mm at 0.1 bar beyond the target preload. We are using a 0.10mm gap feeler to check. If you do not have a gap checker, you can get close by watching the flapper to move ever so slightly.
6. If the gap was correct in step 5, go to step 7. If the gap is not correct, you fine tune by adjusting the actuator rod. Shorten the rod to add more preolad. Lengthen the rod to decrease the preolad. Repeat steps 2-6 until the preload is correct.
7. Reattach the cotter pin. You turbo is now correctly adjusted.