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Smart Tuner SMT8-L - Boost Controller Application | Application Note : AN 10



Perfect Power Application Notes.


Application Note - AN 10


This application note describes how to use the SMT8-L as a Boost Controller.


Boost control is necessary on high compression engines but it is also useful on decompressed engines. The SMT8-L can regulate the boost pressure for different RPM's and can even target a specific pressure in "closed loop".


A boost solenoid is required. The most common is made by Eaton p/n 058906283/F this solenoid has three outlets or pipes. Two of the pipes are the same size and the one with the restrictor connected to the turbo outlet or to the plenum chamber. The other pipe is connected to the waste gate canister. The third pipe is left to "vent" into the atmosphere.


SMT8-L Piggy-Back Unit - Boost Controller Application Hardware



SMT8-L Installation

Follow the diagram below to install the SMT8-L on an aftermarket turbo installation :


SMT8-L Piggy-Back Unit - Installation Wiring

See diagram below on how to install the SMT8-L to an existing engine, which has the boost solenoid as standard.
SMT8-L Piggy-Back Unit - Install SMT8-L on Engine with standard Boost Solenoid
Note : The 1k resistor is necessary to avoid the OEM ECU from detecting that it no longer has control over the boost solenoid.
If you want to raise the boost pressure above the factory standard you will need to intercept the OEM's map sensor signal. The SMT8-L can then be set to "clamp" the voltage so the OEM ECU does not detect any over boost pressure. See wiring below.
SMT8-L Piggy-Back Unit - Boost Pressure Above Factory Standard

SMT8-L Boost Setup

There are three software screens where the boost is configured : Parameters (Shift+F1), Systemdef (Shift+F2) and Boost (F7).
SMT8-L Piggy-Back Unit - ShiftF1 - Parameters
The Boost gain must be set higher than 1 to enable the "closed loop" circuit. If you don't want closed loop boost control, make the gain zero.
Tick the boost output.
SMT8-L Piggy-Back Unit - ShiftF2 - System Definition
Boost PWM low is for throttle positions 1-8. Boost PWM high is for throttle positions 9-16. Boost AMP target is for closed loop boost for the 24-RPM sites. Each site can have a different target boost pressure. Boost Air Temp is added/subtracted from the base PWM.
SMT8-L Piggy-Back Unit - F7 - Boost Control


In this application, boost is regulated to your desired level in closed or open loop control.