# Nozzle sizing/dual nozzle question



## KubotaPowered (Jan 27, 2005)

3.0 VR6 9.5:1 compression, Vortech V1, 14psi of boost, nonintercooled, forged pistons and rods, 440cc injectors and Lugtronic, Snow Performance running through the ECU, 11.7AFR at redline. I'm running about 16.5 degrees of timing at full boost/redline witout knock. Adding half of a degree more nets a power loss of about 8whp but not hearing detonation. The nozzle that is being used is a 375ml nozzle which seems adequate correct? Would like to run two smaller nozzles to total ~375ml-425ml for better atomization. Will there be any benefit with two nozzles or stick with one?


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## [email protected] (Aug 1, 2011)

normally when you run two nozzles, one is supposed to be placed post intercooler for cooling.


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## [email protected] (Jan 13, 2005)

KubotaPowered said:


> Snow Performance running through the ECU


You mean you're using your Lugtronic ECU to trigger and control the water/meth pump? If so, you're matching spray volume to engine load, correct? It's a true map and not on/off control, right?



> Adding half of a degree more nets a power loss of about 8whp but not hearing detonation.


Okay, that's normal.



> The nozzle that is being used is a 375ml nozzle which seems adequate correct?


It depends on the pump pressure that you're running. If you've got it at the standard 180 or 220 setting (depending on version), then I'd say that this nozzle is probably on the large-ish side. Since you're not intercooled, there might be so much heat that it fully evaporates. However, it's also probable that more pressure behind a smaller nozzle (or a pair of them) will evaporate faster, turn into smaller droplets, and thus distribute among cylinders better. It's certainly worth the effort to experiment a bit.



> Would like to run two smaller nozzles to total ~375ml-425ml for better atomization. Will there be any benefit with two nozzles or stick with one?


Atomization is GODLY. Spacing nozzles apart from each other is very smart so long as you can move them apart a fair distance like... 24" or so. (Much less than this span won't produce a big distinction between single and dual.) Btw, where is the single nozzle right now? It should be immediately after the charger since you've got no intercooler. That's where the spray will see maximum heat and turbulence. A second nozzle would be best placed in a TB spacer plate.


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## KubotaPowered (Jan 27, 2005)

Yes, I have the ECU triggering the pump based off MAP, RPM and TPS. The current single nozzle is actually in the charger itself just before the outlet. I have to say that I am very happy with the performance of the kit, not to mention taking full benefit of the system in the tuning. I've always thought that the further away the nozzle is from the throttle body, the more of a cooling effect it has and the closer to the throttle body, the more of an octane bump you see. All due mainly to evaporation and length of the plumbing.


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## [email protected] (Jan 13, 2005)

KubotaPowered said:


> I've always thought that the further away the nozzle is from the throttle body, the more of a cooling effect it has and the closer to the throttle body, the more of an octane bump you see. All due mainly to evaporation and length of the plumbing.


This is all 100% correct. Btw, I'm the guy that brought this point to the VW/Audi enthusiast space. It's the technical justification for the dual nozzle set up that USRT has championed since day one. :thumbup: 

P.S. Ask Snow Performance about it and they'll even tell you it makes no difference. Nonsense! :laugh:


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## 96AAAjetta (Jul 7, 2008)

Not trying to jack the thread but i have a question that seems pertinent to the topic. If you were to run dual nozzles, one near the TB, and one just after a FMIC, both running off the same pressure, would you want them to have the same sized(LPH/GPH) nozzle or different?


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## [email protected] (Jan 13, 2005)

96AAAjetta said:


> If you were to run dual nozzles, one near the TB, and one just after a FMIC, both running off the same pressure, would you want them to have the same sized(LPH/GPH) nozzle or different?


Running different sized nozzles is entirely fine, my man. Generally, I recommend placing the larger of two after the IC and the smaller one after the TB (-NEVER before it if you've got DBW). This allows for the extended distance from IC to combustion chamber to be used for evaporation (which provides the cooling benefits). :thumbup:


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## mk4vrjtta (Feb 3, 2007)

not trying to hijack the thread either, but i was going to move one of my nozzles right after the blower, and was wondering if it mattered that there is 90degree bend in the boost piping appx 1ft after the nozzle?


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## [email protected] (Jan 13, 2005)

mk4vrjtta said:


> not trying to hijack the thread either, but i was going to move one of my nozzles right after the blower, and was wondering if it mattered that there is 90degree bend in the boost piping appx 1ft after the nozzle?


Yes, it matters. However, it probably matters less than completely. My intuition says that within 12" the spray should be evaporated enough to make wall wetting not a critical concern.


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## mk4vrjtta (Feb 3, 2007)

okay, thanks for the help. ill be doing that within the next week or as soon as i get around to rebuilding this blower :thumbup:


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