How Much Water To Inject?

E

EPA Violator

CR Wrencher
Joined
Mar 8, 2008
Messages
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My truck is a 700-800 hp CR, twins all that crap and I am installing a snow water injection, what size nozzles are you all using on this kind of application, seems as though the one 625 will sure pump a lot of water, thought about using the one 625 nozzle and having it start to spray at 25 psi and full spray at 40 psi, I see mid 70's max for boost, and I am using the 220 psi pump. Thanks, Jay
 
My truck has less than half the air flow as yours, I'm sure, and I've put over half a gallon a minute into it at as low as 15 PSI of boost.

They can take a lot of water; it's hard to get in trouble (hydro-lock wise, not headgasket-wise) with a little electric pump.

Most guys end up with 2-4 of those "625" nozzles, at which point the electric pump is out of pressure.
 
Well, I am spraying a 325 nozzle pre cac about 5" from the secondary discharge, a 625 in the intake horn, and a 315 in the intake plate feeding cylinders 5 & 6. I'm runing mostly water with a little methanol, maybe 20%. I didn't gain anything on the dyno using it, and my temps at the track are around 1450. I have it set to come on at 25, on full at 55. I tried using it the other day while towing my boat, set to come on at 18, and on full at 30, but it was puting out the fire. I still need to tune it.
 
I use a Stage 3 MPG max with -20 washer fluid with the first stage coming on at 7, full at 40, power stage on at 25 (highest available). I've been adjusting the % around using the smallest nozzle of the 3 as the first stage. When the power stage came on it seemed to be too much. I recently switched things around to where the 625 nozzle is the first stage and the other two are the power stage and it seems to be working better.
 
If you set the on at about 25 and full on at 55, instructions say the pump comes on at 10% of the full pressure, thats about 20 psi, if the boost is 25 and the pump is putting out 20 psi it won't spray at all, maybe just dribble, I was considering just making it come full on at 30 psi. What do you all think? Jay
 
Huh, Imagine that. Well give it a shot and report back, I didn't think that much into it. Maybe that's why I don't notice any change in egt's. Thanks Man!
 
EPA Violator said:
If you set the on at about 25 and full on at 55, instructions say the pump comes on at 10% of the full pressure, thats about 20 psi, if the boost is 25 and the pump is putting out 20 psi it won't spray at all, maybe just dribble, I was considering just making it come full on at 30 psi. What do you all think? Jay
Click to expand...

Actually, the system starts at 10% duty-cycle of the pump. Not 10% pressure.

That means the pump is cycled on/off rapidly such that it's actually running 10% of a given measure of time. 50% would have the pump cycled on/off such that it amounts to 50% run time, etc. In a nutshell, the DC power to the pump motor is pulsed.

The idea being that the pump potentially develops full pressure for the sake of best nozzle atomization, yet the overall volume delivered is altered. ;)

Make sense?
 
BC847 said:
Actually, the system starts at 10% duty-cycle of the pump. Not 10% pressure.

That means the pump is cycled on/off rapidly such that it's actually running 10% of a given measure of time. 50% would have the pump cycled on/off such that it amounts to 50% run time, etc. In a nutshell, the DC power to the pump motor is pulsed.

The idea being that the pump potentially develops full pressure for the sake of best nozzle atomization, yet the overall volume delivered is altered. ;)

Make sense?
Click to expand...



No sense.....the pressure WILL be less at 10% duty cycle, or how would it effect volume. Lets say the pump will max out at 220 psi on your nozzle set up, now drop the duty cycle of the pump to 10% and you sure arn't going to have 220 psi still.
 
EPA Violator said:
If you set the on at about 25 and full on at 55, instructions say the pump comes on at 10% of the full pressure, thats about 20 psi, if the boost is 25 and the pump is putting out 20 psi it won't spray at all, maybe just dribble, I was considering just making it come full on at 30 psi. What do you all think? Jay
Click to expand...


I'd set it to full on at 30psi, that one pump is going to be like pissing on a bon fire anyways. (If your trying to cool that 800-900 hp)
 
Joesixpack said:
No sense.....the pressure WILL be less at 10% duty cycle, or how would it effect volume. Lets say the pump will max out at 220 psi on your nozzle set up, now drop the duty cycle of the pump to 10% and you sure arn't going to have 220 psi still.
Click to expand...

Think about it like pulsing a nitrous solenoid. If you have 1000 PSI behind the solenoid, you can open the solenoid 50% of the time, and you will be flowing half as much nitrous as if it was open 100% of the time, but the pressure drop across the solenoid won't change much since the transition time from open to closed is so rapid.


If the orifice after the pump is a given size, then when the pump is turned on, it will build a given pressure. If you turn it on and off rapidly, it will build that given pressure while the pump is on, then drop it while it's off. Depending on the elasticity of the system between the nozzles and the pump, and how fast pressure drops when the pump is off, there will be more time at a transition pressure than if it was pulsing a solenoid.

But the concept at least is to maintain a constant pressure while controlling flow.
 
EPA Violator said:
My truck is a 700-800 hp CR, twins all that crap and I am installing a snow water injection, what size nozzles are you all using on this kind of application, seems as though the one 625 will sure pump a lot of water, thought about using the one 625 nozzle and having it start to spray at 25 psi and full spray at 40 psi, I see mid 70's max for boost, and I am using the 220 psi pump. Thanks, Jay
Click to expand...

I think if you are only going to be using one nozzle into the intake horn then dont even bother. the water will not reach all the cylinders to help cool the motor evenly. I am running 5 small nozzles in my set-up. one for each cylinder with the exception of the back two cylinders they share one nozzle. the nozzles are drilled and tapped into the bottom of the intake on the head directed towards each cylinder. With my flux 3.5 and my silver bullet sled pulling I see 1250 to 1300 on the egt the entire time the system is on.
 
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Well, I got to thinking back to physics class and ohm's law (V=IR) and if I use two 625 nozzles tee'ed off from the one line from the pump this would be a parallel circuit so I would lower the total resistance to flow and increase the total flow and still maintain same pressure in both nozzles I think I am right.
 
You only maintain the same volt drop across the nozzles if the pump supplies sufficient amperage, though.
 
Yeah, that's what I mean V is for volts or with water injection pressure drop, I is for current or with water injection flow in volume per time and R is for resistance. Am I correct in thinking that using a tee to two nozzles will maintain the same pressure that would be in one nozzle but will just increase flow because total resistance is decreased compared to just one nozzle? All of this is assuming the pump can flow enough of course, which I hope is the case. Does anyone know the flow rate of these pumps? I have the 220 psi upgrade from Snow. Thanks,Chris. I will call you in a few minutes. Jay
 
EPA Violator said:
Yeah, that's what I mean V is for volts or with water injection pressure drop, I is for current or with water injection flow in volume per time and R is for resistance. Am I correct in thinking that using a tee to two nozzles will maintain the same pressure that would be in one nozzle but will just increase flow because total resistance is decreased compared to just one nozzle? All of this is assuming the pump can flow enough of course, which I hope is the case. Does anyone know the flow rate of these pumps? I have the 220 psi upgrade from Snow. Thanks,Chris. I will call you in a few minutes. Jay
Click to expand...

sounds like a lot of work/
 
Yes, two nozzles in parallel will both have the same pressure.
 
Begle1 said:
Think about it like pulsing a nitrous solenoid. If you have 1000 PSI behind the solenoid, you can open the solenoid 50% of the time, and you will be flowing half as much nitrous as if it was open 100% of the time, but the pressure drop across the solenoid won't change much since the transition time from open to closed is so rapid.


If the orifice after the pump is a given size, then when the pump is turned on, it will build a given pressure. If you turn it on and off rapidly, it will build that given pressure while the pump is on, then drop it while it's off. Depending on the elasticity of the system between the nozzles and the pump, and how fast pressure drops when the pump is off, there will be more time at a transition pressure than if it was pulsing a solenoid.

But the concept at least is to maintain a constant pressure while controlling flow.
Click to expand...


WRONG

This isn't pulsing a solinoid, this is pulsing current to a DC motor, that in effect slows down the rotation of the motor, therfore reducing flow and pressure.




EPA Violator said:
Well, I got to thinking back to physics class and ohm's law (V=IR) and if I use two 625 nozzles tee'ed off from the one line from the pump this would be a parallel circuit so I would lower the total resistance to flow and increase the total flow and still maintain same pressure in both nozzles I think I am right.
Click to expand...


Seems to me those little pumps are internally regulated, so to a point adding another nozzle might keep the same pressure (flow that was regulated is now going to the nozzle)

Now if there is no internal regulation (or already flowed out with one nozzle) adding more nozzles can only lower pressure with increased flow.
 
Joesixpack said:
WRONG

This isn't pulsing a solinoid, this is pulsing current to a DC motor, that in effect slows down the rotation of the motor, therfore reducing flow and pressure.
Click to expand...

What's the PWM's hertz rate?

If it was something slow, like 10-20 hertz, with a ridgid line, large pump and small orifice, I bet it'd be effective.
 
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