This is how it all starts, ’04 Suzuki GSXR600 throttle bodies bought off of eBay for 50$ in Nov ’05. I became infatuated with individual throttle bodies many months earlier after reading about them at the TWM and Jenvey websites. I came across the HomeMadeTurbo article where they took GSXR throttle bodies and put them on a Honda, then I thought to myself this would be a lot of fun putting together a kit of my own, then slapping it on my Miata. I’d get a lot of hands-on work, plus I’d learn a lot about engine management and tuning. And what better way to learn about engine management and tuning then to get a MegaSquirt :). I ended up going with the MS1 V2.2 board with Megasquirt N Spark Extra because it was the cheapest alternative while providing everything I needed from an EMS, and for 120$, you can’t go wrong! More details on the Megasquirt can be found on its own page. Let’s get on with the build!
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Alcohol/Water Injection courtesy of eunos93
The kit operates like this:
The boost switch & map sensor are connected to the same hose the boost gauge is connected to.
The boost switch is normally off, when a certain pressure is reached, it swithes on the current. Which then switches on the relay. The relay & boost switch are made part of the ignition circuit (same circuit that lights up the dash), which only activates when the car is turned on.
The relay, once activated, then switches on the +12V from the battery. That current switches on the solenoid check valve, and the current will flow to either the shurflo pump (only if the controller bypass switch is on) or the +12V lead of the microprocessor controller (for progressive control mode). The map sensor output is fed to the controller.
The controller being used is the Devilsown controller, you can read about it here:
Whether the main current flows straight to the pump or to the controller, is determined by the switches on the control console.
Here are images of the overall layout, and the circuit diagram.
The boost switch connects the circuit at 4 psi (user adjustable), basically activating the controller and opening the solenoid valve to the water/alcohol line. The MAP sensor output to the controller simply regulates the voltage to the pump thereby controlling the injection flow rate.
The controller is akin to a MAP sensor output controlled solid state potentiometer, i.e. higher the boost, higher the voltage to the pump. Parameters are set on the controller, psi at which flow begins, and psi at which the pump reaches full flow (12V).
On this setup, the pump begins injecting around 5 psi, and reaches full flow at 8 psi.
The control console simply houses the switches and the alcohol/water tank low level light. One switch allows bypassing the progressive controller for single (full) flow rate mode. This mode is full flow rate, or off – of course this mode is only used if the controller where ever to fail.
The other switch (spring release) is for manually switching on the pump to full flow rate at any time, for testing purposes. The switches are included simply as a means of fault finding, should one ever occur.
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