Boost Controller Set-Ups

We've compiled a few diagrams and instructions to reference when setting up your boost control system. We hope they help alleviate some of headaches associated with setting up your turbocharger(s) system. Let us know if you have any questions or comments.

External Wastegates

3 port solenoid (single)

Using a 3 port solenoid such as the common 3 port MAC valve in a conventional, external wastegate set-up, you are controlling the amount of pressure being applied to the top port of the wastegate. Increasing the amount of pressure applied to the top port will also increase the amount of pressure (boost) needed on the bottom port of the wastegate in order to open the wastegate. This raises the overall boost level seen at the engine. Normally the boost controller/ECU will utilize a Pulse Width Modulated (PWM) output to control the ground (-) side of the solenoid. In this set-up, increasing the time that the solenoid is energized will increase the amount of pressure to the top port. Most aftermarket electronic boost control systems utilize this style of control.

3 port solenoids (dome control style)

Dome pressure control is most often used with an external high Pressure Source (100+psi) such as compressed air or CO2. The Boost Fill solenoid will regulate when pressure is added to the top port (aka Dome), and the Boost Vent solenoid will be used to bleed pressure off of the Dome. Using these two solenoids, along with a Dome Pressure Sensor, a target Dome pressure can be achieved. This system is a bit more complicated to set-up, as it requires extra parts, multiple inputs and outputs on an ECU to be used, but has its advantages in applications where very high boost pressures are needed and/or where high turbine drive pressures (aka EMAP or Exhaust Manifold Absolute Pressure) may push the wastegate open with conventional single solenoid boost control systems. Most people do not need to use this style of system, although on some systems (ie. some Holley engine management systems) this is the only option recommended by the EMS company.

4 port solenoid

4 port solenoids take the single 3 port control method one step further. By simultaneously reducing the pressure to the Bottom port as it increases pressure to the Top port, this method allows for a much wider range of target boost pressures than the single 3 port control method. This is useful in traction-limited vehicles that require high boost pressures to achieve max power (ie. small displacement engines), but where lower gears/speeds require much less power than higher gears/speeds. This method has many of the same advantages of the 3 port Dome Control Style, but with a less complicated set-up and control system.

Internal Wastegates

2 port solenoid (bleed style)

Internal wastegates operate a little differently than external wastegates. Virtually all OEM vehicle manufacturers utilize internal wastegates in their turbocharger designs due to space limitations/constraints. Most (NOT ALL) internal wastegates use pressure seen at the top port of the wastegate actuator to control the opening of the wastegate. The most common method used by OEM manufacturers is to use a 2 port 'Bleed Style' solenoid. This solenoid, when opened or PWM'd, will reduce the pressure being sent to the wastegate actuator by a certain amount, thus requiring a higher Boost source pressure to be made in order to apply the pressure needed at the actuator in order to open the wastegate.

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3 port solenoid

In an internal wastegate set-up, a 3 port solenoid acts very similar to a 2 port solenoid. The difference is that when the solenoid it activated/ PWM'd, the wastegate actuator's pressure is not only being bled off, but at the same time the Boost source pressure signal is being completely removed from the wastegate actuator circuit. This usually allows for a bit more range in target boost pressures over a conventional 2 port solenoid system.

Manual Boost Controllers (MBC's)

Manual boost controllers take either direct pressure reduction or pressure bleeding in order to mechanically change the pressure signal (source) being sent to the wastegate. We recommend only using a 'ball and spring' style MBC as we've experienced the best luck with these out of the different styles available. The 'ball and spring' style uses a ball (usually steel or nylon) that is preloaded with a spring to restrict the Boost source pressure being sent to the wastegate/wastegate actuator. The spring has an adjustable preload which when increased (tightened), requires a higher amount of Boost source pressure on the ball in order to overcome the spring, and allow pressure by to the wastegate/wastegate actuator.