water injection wiring theory

[l67 vy]

hi guys ive been toying with the idea of water injection and wiring up an extra injector. ive found that if I piggy back the injector to another injector it will most likely damage the computer. so im asking, would this still occur if I only hook it up to the earth side of the injector, would it switch on and off still or is the earth on the commodore injectors constant?
if its constant would anyone else have any ideas of how I could safely wire up an injector?

[Holden202T]

I am assuming this is in a VY L67 ?

im not sure if its the same or not, but I know with say the 808 computer if your running a 6 cylinder there is capacity there for it to run another 2 injectors which would be used in a V8 configuration anyways, but like I said, not sure if the later model computers can do the same or not.

the other thing to keep in mind is if you are doing it via your suggestion, I believe that will be sequential injection, so it will more than likely create un-even water pattern, ie, it injects water for 1/6 of the time the motor is rotating, so one or two cylinders might get all the water and the rest will get none....

I have thought about the same thing, and the only real solution I have come up with using an 808 ecm is to use a flex output to drive a relay to inject it under boost and over a certain amount of rpm's .... and then its just fully on or off ....

the other thing to keep in mind is if the injector is too big and its on all the time you'll flood the motor! .... I haven't been able to work out a way to restrict this to a small enough amount of flow and still be on all the time .....

[immortality]

Their is a thread on Just Commodores with this exact conundrum (using an extra fuel injector to inject water with a sequential type injection system).

Might be worth a read as the OP has put together a little external controller for the extra injector.

Then there is the question of injecting before or after the blower?

A really simple set up would be to take boost pressure from the LIM, to a container with water/meth going to an injector/spray nozzle before the blower. Then you simply adjust the size of the spray nozzle to adjust the flow and you have a simple boost referenced injection system. You would however need to fit some sort of boost activated valve in the line between the LIM and water container to prevent and back flow when the LIM is under vacuum. The down side is that you risk damaging the blower rotors/coatings

[antus]

There is also the question of rust. I take it from the fact people are doing it that regular injectors dont rust internally when injecting water, but does anyone have any data on that?

I would be wary of adding injectors in parallel. No wiring without extra logic will prevent the resistance dropping at the injector driver and less resistance=more current=more heat on the driver. Perhaps it would survive, but I'd keep a spare pcm on hand if your going to test it. Also be aware that changing the properties of 1 injector circuit only will likely have some side effects on the fueling to just that 1 cylinder and you wont be able to see that on a wideband after the combiner in the exhaust.

[l67 vy]

yes it is in a vy l67. the computer I believe wont be able to handle the flex output, but your idea of running it in 8cyl mode sounds like and idea. would the vt pcm be able to do this?? ive set it up so the pump will run constant but im trying to work out a way to make the injector pulse. im running pre charger (another debate but im willing to risk the rotor coating to save the motor) and I would prefer the injector to pulse every few as this will limit hydro lock.

[Charlescrown]

Why not set it up with a small jet before the supercharger and use a set pressure switch to allow fuel flow and pump turn on. The gear is all very cheap and if setup well work fine to reduce detonation. You should also run a 50/50 mix water and Methanol.

[immortality]

Why not set it up with a small jet before the supercharger and use a set pressure switch to allow fuel flow and pump turn on. The gear is all very cheap and if setup well work fine to reduce detonation. You should also run a 50/50 mix water and Methanol.

Tell me more, keen to know more about this set up.

[Charlescrown]

You can buy commercial kits for the purpose (check ebay) but if you do a bit of research you can but all the bits a little cheaper. You need the following items. A suitable size tank (some windscreen washer bottles will do most are resistant to Methanol) a pump (caravan water pumps are OK) a pressure switch in the manifold to turn it on and a bit of playing with some Holley carbie jets placed before the supercharger works well and is simple. They say Methanol eats alloy but with 50% water mix the corrosion rate is very slow. The mix if correct with your petrol will help suppress detonation to quiet a degree allowing more timing. There are some very good articles on the net about the setup. There are lots of arguments relating to the advantages/disadvantage so do some research and you be the judge.

[immortality]

Yeah, I have seen some of the kits. Some are a fair few $$$$.

[l67 vy]

I found a wiring diagram on jc that I will be using for the injector option.
one other option I looked at was similar to charlies but instead of a pressure switch I would have one of those switches with the metal spring on the tb to open at x% of throttle