Ensure you have an overboost cut-out. This is a safety feature built into basically all factory, aftermarket & programmable ECUs. You can never be too careful. Make sure it is set at a sensible & reasonable limit. Increasing the boost will put more load on your engine and there are other tune-related factors you must consider. If in any doubt, speak with a professional tuner/calibrator.

In basic terms, traditional pneumatic actuators for wastegate control are boost-based, meaning they use a positive pressure to overcome a built-in/pre-fitted mechanical spring which then ‘actuates’ and opens a wastegate flap on the turbocharger so that exhaust gas can bypass the turbo & boost can be modulated. As the turbocharger creates more boost, the actuator has more potential force with which to overcome the spring pressure & open the wastegate flap. With Vacuum-Based Actuators however, the reference signal is a vacuum (negative pressure) instead of boost (positive pressure). This vacuum is generally sourced from a vacuum pump fitted to the engine (Either a mechanically driven, or electronic). The vacuum, unlike boost-based systems, is consistent and does not change based on the boost pressure, RPM’s or power the engine is producing. Due to this boost control strategy is very different from a boost-based system.

The simple answer is leverage. We have created bolt-on upgrades for various vehicles fitted with vacuum actuators from the factory as when tuned, the forces can be greater and higher boost levels can be harder to achieve. As the additional boost cannot be used to assist with holding boost like a boost-based system and the tuning window is limited. By utilizing the improved working area & revised springs selection of a Turbosmart Vacuum vIWG you can expect to increase boost pressures to new, higher levels than your factory actuator.

There are a few reasons you might consider this based on your turbocharger system, however, the most common we have come across is to assist with achieving cold-start emissions requirements. Traditional Boost-based pneumatic actuators require boost (positive pressure) higher than the base spring pressure in order to open and while this generally does not cause any issues, it may do if your goal is to open the wastegate flap for cold starts. Often manufacturers use this strategy of opening the wastegate flap on cold starts at idle in order to increase the warm-up rate of the emissions devices such as catalytic converters. Cold-start conditions are often the hardest part of gaining emissions compliance for upgraded and modified cars and a retro-fitted vacuum vIWG from Turbosmart can help.

You will need an ECU and solenoid in order to manipulate the actuator successfully. The boost control strategy will be different from that of a boost-based system and if your vehicle was already fitted and calibrated for a vacuum IWG, returning and calibration will likely be required. As with all boost control changes, air-fuel ratio, torque and power must be checked.

The Turbosmart vIWG Vacuum Actuator series has been engineered with a second chamber on the other side of the diaphragm which means you can boost assist. This will require a more advanced strategy and setup however plumbing positive pressure from the inlet manifold or turbocharger directly, or via a solenoid will allow a custom, much wider tuning window.

The swivel banjo and fitting in the top cap is a -3AN and the lower (optional) positive Pressure Assistance Port for Boost-Assist is 1/16NPT.