Welp, I'll start off by saying that I'm no electronics expert by any stretch of the imagination, but I picked up a few things in the last couple of days..

I wanted some way to control how much water my injectors let in, so I came up with this simple schematic.. There are tons of other ways to do this, but I think this is one of the cheaper and simpler units..

Here is the schematic, and I'll briefly go through how I think it
*should* work..

Schematic:
http://personal.nbnet.nb.ca/mbezeau/.../inj_timer.jpg

Desc:

The hobbs switch (soon to be a boost sensor) powers the circuit when the preset boost level is achieved. The bottom timer (Astable) triggers the top timer (Monostable) every 1.18 seconds.. The top timer, when triggered, will turn on the injector(s) for 0 to 1.1 seconds depending on where the potentiometer is set.. So, if your potentiometer is set to the middle (50k ohms), then your injector(s) will come on for .55 seconds and stay off for .55 seconds plus the .03 seconds between the time this stops and the time the Astable timer is triggered again.. If you set the pot to 3/4 (75k ohms) your injector(s) will turn on for ~0.83 seconds then shut off for 0.30 seconds until it is triggered again for another 0.83 seconds..

It's still not perfect, but since I just started designing/learning
yesterday, you gotta give me a little slack..

Opinions welcome!

Cheers,

 

so are you hoping to put a 2 or 3 bar MAP sensor and a potentiometer in series to make that thing more adjustable? a map is a potentiometer based off its bar measurement.

 

If you're asking if I'm going to wire in the map sensor so as boost increases, so does the amount of water injected, well....

Eventually I'll probably add it, but for now I want to get this schematic refined to the point I'm happy and convinced it will work.. Maybe use some LM1949S chips for injector drivers..

By the end of this project, I'd like it to be equal to those 300 dollar units you see for sale.. (in quality/functionallity, not price )

As well, there is no reason why you couldn't use this for extra fueling on a carbed engine.. A fuelie engine would be difference because you could take the signal from the wiring harness and fire extra injectors that way.. (not quite that simple, but you get the idea)..

Cheers,