maximum flow for 0.4 mm, 0.5 mm, and 0.6 mm Aquamist nozzles
 

This is for my supercharged Focus (big boost Jackson Racing Eaton/roots style supercharger running 14 psi of boost). I'm not sure which nozzle will be best to start with, and I want to know what the maximum flow rate is for those three sizes. The 1s kit comes with the 0.5 mm nozzle, if I'm not mistaken, but I wonder if this will be too much for a Focus that is (before injection) making about 180 whp. Should I start with the 0.4 mm nozzle?

I think the 0.5mm jet is a good start. I based the WI rate by your power output of 180whp. Not sure what that would translate it flywheel HP - I guess it will be around 220-230HP?

You will require approximately 500-600cc/min of fuel per 100BHP. if you are injecting 1.1 litre of fuel /min then one 0.5mm jet will equate to about 20% of water to fuel ratio.

We normally recommend between 10-15% but due to your lack of intercooler and making boost on top of the standard compression ratio(?). I think 20% is about right.

Please post your results when possible.

Richard,

Another relevant question I think:
Is there any rule-of-thumb regarding the activating boost-pressure for the WI?

Thank you, Richard. On the Focus, 180 whp works out to probably around 210 flywheel hp. Does this change your assessment any? Thank you for the information!

No, 0.5mm jet is fine, roots type supercharge tends to have higher discharge temperature than the centrifugal type, the 0.5mm jet shoudl work well.

John,

Rule of thumb for the onset of water injection for normal unmodified factory car should be just nelow the factory boost pressure.

10% of water will normally allow 1 compression ratio increase or arounf 3.7psi. Other factory such as ambient temperatures and fuel grade woudl affect the quoted figure.

Mushin,

Does the Jackson Focus kit come standard with 14psi?

That's roughly what I thought.
Cheers Richard, I'll add this info on my website if you don't mind 8)

Richard,

No, it comes stock with 5 psi, at best. I have a larger crank pulley and smaller supercharger pulley, 42 lb. fuel injectors, and custom tuning.

Mushin,

Unless you have your compression ratio decreased, you need to run at least a 0.7 or 0.8mm jet - no intercooler assumed.