Hi everyone,
This is my first ever post. I'm a novice really when it comes to electronics.

I'm wanting to use a 555 timer circuit to pulse 6, 12v, 125ma solenoids. All at the same time. The solenoids I've ordered are from eBay and are supposed to react within under 50ms. I assume that means around 20hz. I understand that does not mean they are designed for continuous pulsing at any frequency however, like 10hz.
These will function on my car to flow water injection. The idea is to use an astable 555 to pulse the solenoids before the nozzles so that I can use duty cycle % to control how much fluid flows per minute for a fixed size nozzle. 100% duty cycle would be 180ml a min.

My question is. If my 555 pcb can flow 500mA max but I have 6x125=750mA then I would need to wire my solenoids in series. This would be useful as if one fails I'd like to know rather than the rest just keeping on working.
My supply voltage is 12v. I wondered how I would know if I can power the 6 solenoids in series?
I also purchased a small 555 driven relay with a 0 to 15 sec delay. It is capable of 10A and says it handles any voltage. I assume up to 220V but i'd be using 12v DC. I could use that driven by the 555 duty cycle generator.

Any thoughts?

Apart from controlling the 6 solenoids. An alternative could be to pulse the DDP 5800 pump. However this flows 12 amps and 14.5 volts. Sounds more difficult but I'm a novice so I don't really know if that's the case?

Thanks

-Jack

 

Picture of the pump:

Picture of the solenoids:

I think I've answered my question. This solenoid needs at least 9.6v to function. Is that correct?
Thanks again.

 

I'm not familiar with water injection. Do you inject all six at the same time?

 

Solenoids are not the way to go: Seehttps://www.rbracing-rsr.com/waterinjection.html

 

The solenoids I've ordered are from eBay and are supposed to react within under 50ms.

I have no practical experience of water injection, but if that means 50mS to open fully and another 50mS to close fully then won't they be too slow by a factor of ~ten? Fuel injectors open/close in just a few mS.

 

I'm not familiar with water injection. Do you inject all six at the same time?

I do yes. I was running 2 nozzles injecting into the charge pipe, which is the pipe leading to the throttle body and manifold. However due to uneven distribution per cylinder, due to airflow within the 6 way manifold I chose to place a nozzle before each cylinder. The problem with this is that my manifold idles at 5 psi below atmospheric pressure, which will draw the liquid into the manifold when it's not required as far back as the nearest check valve or solenoid acting to stop this.

 

Solenoids are not the way to go: Seehttps://www.rbracing-rsr.com/waterinjection.html

A descent article but I don't agree with everything there. It seems a bit too simple.

I do flow water and methanol. Originally for octane but now as a fuel source.

I've used toluene, isopropyl alcohol, ethanol etc and I can tell you that nothing, bar nitromethane(which I can't use) compares to methanol. I skimmed through that article but it doesn't make that clear. Isopropyl is also far more expensive than ethanol or methanol which that article appears to make a mistake about. Methanol is a great coolant, both pre and post combustion, unlike isopropyl alcohol, so I would take that article as a guide rather than an informative writing. The reason for this is that meth has a high latent heat of vaporization, contains far less carbon and so combusts into more water than other fuels, also taking heat out of the cylinder as it leaves as steam. Toluene is a horrible fuel. It's carcinogenic, has a high boiling point which means it forms muck on hot surfaces, coating them in carbon. It also requires nearly as much oxygen to combust as gasoline so it can't be used to produce much more power without lots more air flow. I.e Turbos, supercharger, nitrous oxide. It only has octane going for it, but if you aren't knocking then more octane is pointless. Also directly injected methanol will effectively give around 180 octane. Ethanol DI around 160.

What's most important to me is to achieve any more than 40 psi where my nozzles will atomize. The 1.3gph pump easily achieves that so I don't need to pay 3 times as much for a pump that can do 1000 psi.

 

With my current setup I use a 1.3gph pump, a single solenoid and check valves ( before each nozzle ) that crack open at 15 psi and correctly sized nozzles.
I can already run 100% duty cycle on my current nozzles. They are sized to be always on once my boost threshold is met and my throttle is 70% or more.
However once the pump shuts off, there is a residual 150 psi of pressure. This equalises within around 2 to 3 seconds once the solenoid closes. This is not causing me problems, however I am keen to experiment with solenoids as 50 millisecond reaction times compared to 3000 milliseconds is a night and day difference. Like HFT compared to a home day trader.

As a 555 also allows me to pulse solenoids I plan to experiment, using my larger nozzles but pulsed to achieve the same overall flow per minute.
I will be installing stage 3 twin turbo chargers next month anyway so a full on 100% duty cycle will be fine. I'm still keen to see if my I can stop methanol within 500ms after the request for meth ceases.


So, do 2 parallel circuits of 3 solenoids each sound possible?

 

I have no practical experience of water injection, but if that means 50mS to open fully and another 50mS to close fully then won't they be too slow by a factor of ~ten? Fuel injectors open/close in just a few mS.

At 7500 rpm red line, there will be 1875 sparks per minute. Across my 6 cylinders that's 312.5 sparks per cylinder, per minute.
This equates to 5.2 sparks per second.

Apparently these injectors can fire under multiple conditions, multiple times per revolution, during all parts of the 4 stroke cycle. So I would not be surprised if there are 3, 4 or 5 times as many injector pulses, even during the compression stroke alone.

5.2hz = 192 ms.

15hz = 66.6 ms

 

Well I got a prototype working. In the end I had to put each solenoid in parallel to make sure they got 12 volts.
Otherwise the voltage drop in 2 parralell circuits of 3 solenoids was enough to cause them not to open.