Suggestion: Water Injection improvements

Testing and development of Megasquirt 3

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Suggestion: Water Injection improvements

Postby jacky4566 » Tue Feb 28, 2017 11:15 am

Looking at other systems like Aquamist can we improve on the MS water injection system?

The aquamist kit uses a flow meter. So "water flow = fuel flow * Desired %". While only having done a few systems myself it seems like this is more logical than a simple PWM based on MAP& RPM.

The Swissflow SF800 is an ideal sensor for this. Affordable, simple, and reliable. Input this on a trigger input to track water flow.

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Re: Suggestion: Water Injection improvements

Postby 93supercoupe » Fri Mar 03, 2017 6:43 am

it would be nice to use a flow sensor. That would allow a fail safe based off meth/water flow.
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Re: Suggestion: Water Injection improvements

Postby tpsretard2 » Fri Mar 03, 2017 7:38 am

a simple pressure switch input on the water line to the high pressure line would also work for protection.

If parameters to injector water = yes and water preesure input is high keep injecting. if low disable pump.
Could also be used for priming the system if you are using a high speed valve/solenoid.

Here is an eq of the switch. ... 0850048233

will use a simple digital input. option should have polarity option, NO or NC
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Re: Suggestion: Water Injection improvements

Postby Suprazz » Sat Mar 04, 2017 4:41 am

with the flow sensor, you can configure a table blending for security.

So if flow is too low or not present, you stay on the ignition table one which is safe on pump gas, and if flow is present, you blend or switch to the second table.
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Re: Suggestion: Water Injection improvements

Postby benckj » Sat Mar 04, 2017 10:47 am

A flow sensors is the best option especially if going to use it as a propotioning tool in a MAP vs WI table. Becomes a little harder to use as a failsafe device given it would have to trigger off a percentage of expected flow vs MAP.

I tend to favour something simple for failsafe operation by using a NC pressure switch. Easy enough to use as direct input the MS or have as an LED on dash. I'm building a switch like this into an accumulator tank positioned after the WI supply tank. Tank will hold the pressure in lines with selenoid opening when WI activated along with pump on. Accumulator allows a quicker response on good place for monitoring pressure in system. Just have to work out way to prime system on start up.

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Re: Suggestion: Water Injection improvements

Postby jesse408 » Mon Mar 20, 2017 7:48 pm

I'm not sure how this is gonna work, but I just configured a generic press sensor on the meth line to JS5 and called it (sensor 1).
I have D15 set to be active when (Sensor 1) > 200psi, and Water Duty > 50% in order to switch to more agressive spark table.
Then, D16 is configured to be active when (Sensor 1) < 180psi, and Water Duty > 50%.
This will switch boost tables to basically just above wastegate (6psi) as a safety measure if there's insufficient meth pressure.
Works on the bench, but haven't yet tested actual pressure thresholds in the car.
It would be wonderful if the low level input would also disable the meth injection and boost controller
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Re: Suggestion: Water Injection improvements

Postby benckj » Mon Mar 20, 2017 8:26 pm

You have gone more complicated than I did which maybe good or bad depending on the reliability. I went much simplier with a single pressure switch on the accumulator tank which will be set around 100psi. If the pressure drops below this pressure for any reason a LED warning dash light will come on. Initially, this will be monitored while driving to commission system then will be connected into the MS to pull timing above a certain MAP value.

It's all installed in the car now but I decided to fit a fuel filter off the tank and am waiting for this to be delivered. In addition to the pressure switch I have also installed an analogue pressure gauge, non-return valve on pump inlet and a push button dash switch to prime/test WI operation. The prime button will be required as the WI will not build pressure until my boost pressure is reached (14psi). Built the whole system from a Chinese alloy fuel surge tank & components for under $50. I will report later on operation with some pics.

Good luck with your project and would to see more detail like a diagram or pics.

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Re: Suggestion: Water Injection improvements

Postby benckj » Wed Mar 22, 2017 1:35 pm

Had a slight set-back with my new 2 litre accumulator tank. Finished installing the fuel filter on outlet and reconnected pump and delivery lines last night. When I primed the system to evacuate air I noticed a few leaks. Upon fixing the leaks I brought the tank up to pressure which severely bulged out the sides.

Although the alloy tank I purchased is for fuel surge and running 2 pumps it is probably only designed for around 60psi working pressure. The WI pump is capable of 200psi but normally operates around 100. I didn't get an accurate reading off my pressure gauge as I released the pressure when I noticed problem with tank. I think the tank will be OK under normal operation but in the event of a block nozzle I could see excessive pressures which may split sides or pop fittings. Thinking I may need a release valve to protect system or possibly another pressure sensor that can cut off pump.

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