This is a basic method to help determine what size water jet to use. This is based on water....Alky injection demands a diff approach to calculating proper jet selection, and a better understanding of alky injection is necessary in order to do that = another thread will be made to address those needing info for alky injection.
Please review the following document: http://www.aquamist.co.uk/info/docum...aper/title.htm for a detailed insight in to what?s going on in the combustion chamber and why water injection if introduced in the right amount is wanted.
In short, the factory is dumping fuel for cooling and knock suppression in order to protect the engine. How much of the total fuel being dumped for this is typically between 10% - 15%. Ideally you want to replace this dumped fuel and instead use water because it does a much better then fuel for this purpose.
Once the things mentioned in the above link become understood the water injection user will realize that ideally he/she wants to introduce water in a ratio of water to fuel. The user also understands that just as with fuel, too much water inhibits or reduces performance. I want to quote one paragraph from the above linked document that IMO will cause the reader here to actually read that document:
"The relationship that you should seek to manage with water injection is the ratio of water to fuel. Metered to exacting proportions as little as 3% water to fuel can replace the amount of heat absorption that fuel previously provided when leaning from 10:1 to 12:1 AFR. There is no system that can meter water in that exacting a relationship with fuel that does not utilize a full fuel injector driver, port installed nozzle jets, high flow pump(s) and a rising rate pressure regulator. At this point you are talking about stand alone engine management like a Motec and a duplication of the fuel system but for water. That being the case the best solution is to use a system that will get you as close as you can to mirroring the fuel injector flow and run at least 10% water to fuel for margin."
Note: On cars that are highly modified or are used in an extreme racing environment more water can be used.
On to a basic method with which to use in determine what water jet to use on your system.
You would need to know before hand:
1) Capability of the fuel injectors your using (cc?s per minute)
2) Rated PSI of the water pump that you intend to use
So if for instance, the fuel injectors in your car are rated at 577cc/min and you had 4 of them, you would be injecting 2308cc/min of fuel (4 x 577 = 2308cc/min). Take this total and times by a percentage between 10% to 15% or maybe even 20 (highly modified)
Here?s some simple examples of how a stage II/III injector is broken down with regards to above
Stage II 100% duty cycle
S2 injectors rated at 682CC x 4 = 2728cc/min x 10% = 273.8cc/min
S2 injectors rated at 682CC x 4 = 2728cc/min x 11% = 300.1cc/min
S2 injectors rated at 682CC x 4 = 2728cc/min x 12% = 327.4cc/min
S2 injectors rated at 682CC x 4 = 2728cc/min x 13% = 354.6cc/min
S2 injectors rated at 682CC x 4 = 2728cc/min x 14% = 381.9cc/min
S2 injectors rated at 682CC x 4 = 2728cc/min x 15% = 409.2cc/min
S2 injectors rated at 682CC x 4 = 2728cc/min x 20% = 545.6cc/min
OK so now you get an idea, but injectors do not typically get maxed out at 100% duty cycle, more likely they are maxed out at 85% duty cycle. So take the total (using stage II/III again) 2728 and times that by .85 = 2318.8. This is a more realistic to real world operating conditions
Stage II 85% duty cycle
S2 injectors rated at 682CC x 4 = 2318.8cc/min x 10% = 231.9cc/min
S2 injectors rated at 682CC x 4 = 2318.8cc/min x 11% = 255.1cc/min
S2 injectors rated at 682CC x 4 = 2318.8cc/min x 12% = 278.3cc/min
S2 injectors rated at 682CC x 4 = 2318.8cc/min x 13% = 301.4cc/min
S2 injectors rated at 682CC x 4 = 2318.8cc/min x 14% = 324.7cc/min
S2 injectors rated at 682CC x 4 = 2318.8cc/min x 15% = 347.8cc/min
S2 injectors rated at 682CC x 4 = 2318.8cc/min x 20% = 463.7cc/min
Now you need to know the capability of the WI pump you are using. If you are using a pump rated at 100psi, such and such jet might flow 280cc/min but that same jet with a pump rated at 75psi might only inject 215cc/min.
Aquamist jets using Aquamist race pump
Aquamist jets using Aquamist/Shurflo 150 psi pump
NOTE: This is a very simple and not a scientific method but it allows the WI user to have a good starting point from which to begin with. Aquamist sells kits with 3 jets to allow the user to tune the WI system to their needs.
Last edited by turbojack : 02-12-2007 at 05:17 PM.
This is great information, thank you!
It's taking information a few knowledgable people on the board have said (and some info they haven't), and phrased it & posted it in a format and wording anyone can look at and apply to their situation.
For instance, in my car I'm running S2/3 injectors that are topping out at 80% duty cycle. That calculates out to between 218.2 cc/min (10%) and 327.36 (15%). My car's pretty modded, but I'm going to steer clear of anything over 15% for now.
That means that my M3 nozzle with my Shurflo pump is a bit undersized, but the M5 I have is most likely too large. So I this point I should probably go to an M4, or switch to an Aquamist injector size (pending flow numbers).
Yes I was thinking about the S3 flow as well when I posted that. But I think (not sure though) Pitviper is using the S2/S3 injectors without the S3 fuel system.
Stage 3 owners need to adjust the math accordingly to reflect the increased flow capabilities of that system.
Yes I was thinking about the S3 flow as well when I posted that. But I think (not sure though) Pitviper is using the S2/S3 injectors without the S3 fuel system.
Stage 3 owners need to adjust the math accordingly to reflect the increased flow capabilities of that system.
You are correct on both counts.
The S2 and S3 injectors are the same, the difference in flow being the rail/regulator on teh S3
This is great information, thank you!
It's taking information a few knowledgable people on the board have said (and some info they haven't), and phrased it & posted it in a format and wording anyone can look at and apply to their situation.
For instance, in my car I'm running S2/3 injectors that are topping out at 80% duty cycle. That calculates out to between 218.2 cc/min (10%) and 327.36 (15%). My car's pretty modded, but I'm going to steer clear of anything over 15% for now.
That means that my M3 nozzle with my Shurflo pump is a bit undersized, but the M5 I have is most likely too large. So I this point I should probably go to an M4, or switch to an Aquamist injector size (pending flow numbers).
I have another question related to this. If these calculations are for water, what happens when you add methanol? On some of the Aquamist literature, it says to add .1mm to the nozzle size for each 25% of methanol you add to your water. How would this convert into the nozzle sizing we use? (M-sizing)
If I'm using an M5 @ 100psi, can I switch to an M5 @ 150 psi with running a 50/50 mix?
This is great information, thank you!
It's taking information a few knowledgable people on the board have said (and some info they haven't), and phrased it & posted it in a format and wording anyone can look at and apply to their situation.
For instance, in my car I'm running S2/3 injectors that are topping out at 80% duty cycle. That calculates out to between 218.2 cc/min (10%) and 327.36 (15%). My car's pretty modded, but I'm going to steer clear of anything over 15% for now.
That means that my M3 nozzle with my Shurflo pump is a bit undersized, but the M5 I have is most likely too large. So I this point I should probably go to an M4, or switch to an Aquamist injector size (pending flow numbers).
I have another question related to this. If these calculations are for water, what happens when you add methanol? On some of the Aquamist literature, it says to add .1mm to the nozzle size for each 25% of methanol you add to your water. How would this convert into the nozzle sizing we use? (M-sizing)
If I'm using an M5 @ 100psi, can I switch to an M5 @ 150 psi with running a 50/50 mix?
All Aqaumist flow recommendation are based on the cooling effect due to the latent heat values.
latent heat table:
To convert 100% water to 100% methanol, you need to multiply the flow by a factor of approximately x2.5. (methanol's mass is x0.8 of water, so injection by volume need to put the density correction). Most non-aquamist systerm uses oil heater nozzle, all based on lb/hr of oil and not litre/hr of water. Viscosity of oil and water is different, it will have some flow difference using those oil nozzle to deliver water or methanol. You need to consult those non-aquamist company for more details.
__________________
Richard L - Aquamist Engineer
Last edited by Richard_L : 01-16-2007 at 02:17 PM.
This is great information, thank you!
It's taking information a few knowledgable people on the board have said (and some info they haven't), and phrased it & posted it in a format and wording anyone can look at and apply to their situation.
For instance, in my car I'm running S2/3 injectors that are topping out at 80% duty cycle. That calculates out to between 218.2 cc/min (10%) and 327.36 (15%). My car's pretty modded, but I'm going to steer clear of anything over 15% for now.
That means that my M3 nozzle with my Shurflo pump is a bit undersized, but the M5 I have is most likely too large. So I this point I should probably go to an M4, or switch to an Aquamist injector size (pending flow numbers).
I have another question related to this. If these calculations are for water, what happens when you add methanol? On some of the Aquamist literature, it says to add .1mm to the nozzle size for each 25% of methanol you add to your water. How would this convert into the nozzle sizing we use? (M-sizing)
If I'm using an M5 @ 100psi, can I switch to an M5 @ 150 psi with running a 50/50 mix?
All Aqaumist flow recommendation are based on the cooling effect due to the latent heat values.
latent heat table:
To convert 100% water to 100% methanol, you need to multiply the flow by a factor of approximately x2.5
I should never try to figure this stuff out on lack of sleep, but it looks like the latent heat of water is about 2x that of methanol? Or do you have to factor in the difference in mass, as well?
And would that make a 50/50 mix need to be 1.25x that off just water?
So, the most volume that you can inject with an Aquamist jet/pump (non-Shurflow) is 310 cc/m (806-325 1.0mm x2.5 for 4mm 310cc/m)? If you want higher flow, can you just use two jets, or would that be too much for the pump?
Yes, the range of aqauamist jet is designed around the Aquamist pump, 1mm is teh largest jet the pump can couple, still producing adequate pressure to atomise the water at "moderate" to "high" manifold pressure "~22psi".
If you put two 1mm jet inline, the pressure will drop and atomisation will suffer, you will not get more flow.
One somple way to increase the capacity of the aquamist pump is to add a push pump, active it when the main pump is running.
Here is a wiring diagram how it is done:
(add a 806-500 priming pump relay driver)
Do you have the cc/min for the 3 jets included in the HFS-5 kit, when used with that kit? I'm just wondering whether one of those included jets is the right size for my application. I'm running 660cc injectors and hit about 90% duty cycle on 93 octane at 22 psi with AFR around 11.2. I intend to inject mostly alcohol or methanol and run at least 26 psi, if not higher. I currently have 344 whp on 93 octane and am aiming for 400 whp with this kit and a cam upgrade, which is not unheard of with the turbo and other mods I have. Is this enough info. to decide which jet is right for me? Thanks.
Based on the 125 low-ripple flow, the flow estimation will be:
(duty cycle is not important, and HFS trac duty cycle)
0.8mm: 300cc/min
0.9mm: 350cc/min
1.0mm: 400cc/min
Approximation above: I will confirm.
Your vehicle: 660x4 = 2649cc/min fuel, 93 octane.
standard boost for normal afr ~11.5-12
water only: 0.8mm
W50/M50: 0.9mm
Methanol only:1mm
for normal afr ~11.5
for +3 to 6 psi boost
water only: 0.8mm x2
W50/M50: 0.9mm x2
Methanol only:1mm x2
for normal afr ~12-12.5 afr
These are guide line only, need to be trimmed during dyno session. For high prercision duty cycle tracking, a small restictor has to be placeb before the HSV. Single jet =0.6mm and 0.8mm for double jet. More detail will be given with inbox instruction.
Last edited by Richard_L : 01-27-2007 at 10:04 AM.
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Help with water injection jet/nozzle selection
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