DIY: Increasing boost on stock wastegate actuator

May 07

One way to increase boost without using the spring is to partially block the boost line going to the actuator – thereby preventing the boost from pushing on the wastegate actuator – that is how many boost controllers do it. Please be careful when using this technique as boost can rise to max out the turbo if you close off too much flow for the boost line.

To manually set your level of boost, you could either buy expensive manual boost controller or opt out for simple industrial 1/4″ npt 2 port valve which will run you about 1/4th the price of the fancy brand name boost regulator.

Example of manual boost controller that I use…

Please note that Line L1 (boost source reference line) can use one of several sources:

  • nipple on turbo housing (it is a factory feature on some turbos)
  • nipple on the cold side intercooler piping
  • nipple on the hot side intercooler piping
  • intake manifold vacuum lines

Line L2 leads to the wastegate actuator (operating an internal or external wastegate).

Please note that there are many forum debates about which boost reference source solution is best to avoid boost spikes.  In this article, we’re just covering the idea for a basic DIY manual boost controller.

This type of valve will handle typically in the range of 100-150 psi so there’s no need to worry about failure due to pressure, but it is important to get the fittings tight & snug to prevent leaks.  The cost for this type of “boost controller” is about 6-7 dollars.

One way to test your boost would be to use pressure gauge and air compressor – if you don’t have either or both – for starters you could blow through it with your mouth and see where the closing point for flow is.. once you find it.. open it up a bit to limit the flow about 1/4 of the way. Then try boosting gently (not just dumping gas and seeing where it hits). If your turbo didn’t gain anything, you must close it up bit more and try again. Once you find the sweet spot on the valve regulator based on the boost level you enjoy, mark position of the regulator knob on the valve – this will help you find it easier in the future should you find reason to change it.

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