hello i'm posting here in an effort to get some guidance as to how to size the two nozzles for my staged water injection setup on my FD. firstly my reasoning for going with a staged setup was that i plan to run 15psi normally but have the option to knock it up to 25psi should i feel the need. logic suggests that the difference in power levels will be significant and because a lot of the injector/nozzle sizing guides i've read go mainly by power i can only assume that the appropriate amount of injectant for 15psi will not suffice for 25psi and the appropriate amount of injectant for 25psi will be overkill for 15psi. so i've opted for two nozzles each with their own solenoid and boost switch one opening at 10psi and the other at 20psi. i am inclined to use the coolingmist super atomising nozzles however if there is no real advantage to using them then i wil go with whatever gets the best recommendation.

onto my setup:

the motor is a freshly rebuilt REW motor with brand new housings and brand new balanced and side clearanced s4 turbo 8.5:1 rotors with std mazda 2mm 2piece seals. it has a medium streetport nothing crazy. turbo is a garrett t04z with a 1.15 hotside with a 44mm tial mvr on a custom manifold with a 4" dump pipe. my water meth system (i plan on running 50/50) is just an alloy tank with a 40micron filter between it and the pump, then -6 hardline under the car up to a y-splitter to two -4 lines that each go to a solenoid then a nozzle into the elbow. i believe the pump is set to run at 200psi. how can i go about figuring out what size each injector should be?

just got an email back from coolingmist also; at 200psi; cm5 flows 340cc/min and cm7 flows 800cc/min.

appreciate any help,
Brad.

 

no help at all?

 

okay so after deciphering howards thread and using the compressor map reading thread in the single turbo section these are the figures that i've come up with:

by using the formular in the compressor map thread i've come up with 380rwhp at 15psi and 510rwhp at 25psi. now these figures do seem a bit low but i'm assuming theyre worked out for just straight pump fuel.

so using these figures in howards formular gives:

380rwhp:
446/350= 1.276 x 1.1= 1.40 x 375= 526cc/min

510rwhp:
599/350= 1.71 x 1.1= 1.88 x 375= 706cc/min

do these figures seem high, low or otherwise?

thanks,
Brad.

 

They both seem correct for those individual hp levels. But your doing dual nozzles in a "staged" system. Having both nozzles running max seems high....but maybe I'm not understanding you completely.

 

I plan to run one 550cc and one 200cc injector, the 550 coming on at 10psi and the 200 at 20psi. Catch mandrift?

 

If I were going down this road with the parameters you've offered, I would use the 340cc nozzles for both the 1st and 2nd stages.

 

Nozzle placement: they're justdummies up with 1/8npt unions to check clearance, they're connected to a y fitting with alloy tube and tube nuts and then a flexinli e connecting to 3/8 hardline under the car.

 

Brad,

i don't have an answer for you as i have zero experience w water but i can give you some things to condsider.

your turbo:

looking at the comp map:

15 psi = 60 pounds per minute = 868 CFM/1.92 = 450 rw rotary hp
25 psi = 72 pounds per minute = 1042 CFM/1.92 = 543 rw R hp

at 11.3 AFR

60 pounds air/ 11.3 = 5.309 pounds gas = .836 GPM or 3164 CC/Min = 97,051 BTUs
72 = 6.37 pounds gas = 1 GPM = 3785 CC = 116,090 BTUs

Gas Cooling BTUs

at 60 = 752
at 72 = 900

AI

energy BTUs

at 550 CC /2 meth 275 CC/Min 4122 BTUs
at 750 CC/2 meth 375 CC/Min 5667 BTUs

cooling BTUs

550 CC (meth and water) 822
750 CC (M&W) 1130

hope this helps...

howard

 

thanks howard i ended up going with a super atomizing cm7 (600cc @200psi) opening at 10psi and a 180cc regular injector (208cc @200psi) opening at 20psi. im thinking i should adjust the pump to run at 150psi so to lower the flowrate; will the extra 100cc/min be any detriment at all?

brad.

ps picture of my solenoids mocked up (just using 1/8 unions for placement while im waiting on the nozzles to arrive:

 

looks good. my guess is you will just have to run it to answer your questions.

good luck,

howard