Water nozzle placement

[JasonCzerak]

Originally Posted by Charles

I literally meant all of the above. Not try each, but do all of the above..at once.

I'm not going to "un-do" what I have setup so far. I figured what I've installed now is the hard part. i'll add more later.

[dvst8r]

I have always been under the impression, that it was the change of state that actually did the work, and the water traveling in suspension, does negligible cooling weather injected prior to the turbo, prior to the intercooler, prior to the intake or right at the back of the valve.

From the little research I have done on this, if you inject it anywhere but into each individual intake runner, it gets thrown right against the bottom of the intake manifold and pools, and the middle runners (in a cummins app) get a ton more water then the outside runners. In a typical side entry manifold the water that is in suspension gets thrown against the far back wall of the manifold and goes down the last runner, or the heavy water droplets that are failing out of suspension drop in the first runner. Leaving the middle runners rather dry.

To me in a cummins app where the stock manifold is already notoriously bad for providing equal amounts of flow, the last thing I want to do is compound it by throwing water down in that same fashion.


Now I could be wrong on all of this, but this is what I have gleaned from people much smarter then I that have done extensive testing on this...

[Charles]

Originally Posted by dvst8r

I have always been under the impression, that it was the change of state that actually did the work, and the water traveling in suspension, does negligible cooling weather injected prior to the turbo, prior to the intercooler, prior to the intake or right at the back of the valve.

From the little research I have done on this, if you inject it anywhere but into each individual intake runner, it gets thrown right against the bottom of the intake manifold and pools, and the middle runners (in a cummins app) get a ton more water then the outside runners. In a typical side entry manifold the water that is in suspension gets thrown against the far back wall of the manifold and goes down the last runner, or the heavy water droplets that are failing out of suspension drop in the first runner. Leaving the middle runners rather dry.

To me in a cummins app where the stock manifold is already notoriously bad for providing equal amounts of flow, the last thing I want to do is compound it by throwing water down in that same fashion.


Now I could be wrong on all of this, but this is what I have gleaned from people much smarter then I that have done extensive testing on this...

You're absolutely right in terms of uniform flow. Although in terms of heat removal, the phase change is a huge energy sink, and does account for the brunt of the heat absorption in most cases. But you can steam water outside the combustion chamber just fine. With IAT reaching and exceeding 400 degrees F boiling water is very possible even at the increased manifold pressures present. Assuming you do this, then you're not trying to flow water, but instead steam.

And spraying pre turbo alters the compressor map. It effectively makes a compressor "bigger" near as I can tell.

[JasonCzerak]

I thought if you sprayed it pre-turbo, you run the chance of wearing down the turbine wheel. kinda like sand,

[dvst8r]

Hmm from the clear manifold testing I watched, it all seemed to be more like water vapor then steam. With that being said I don't recall the outlet temps ever going over about 320F and the highest boost pressure was only in the mid 30's (34psi iirc).

My point was that from the testing I saw, it didn't mater if the water was injected before the intercooler or just before the valve, the amount of cooling was the same. There was no evidence to any cooling from it having time to travel in the intercooler piping system, it was all from the state change that happened in the combustion chamber.

I see what you're saying about if the compressor discharge temp is high enough the state change would happen in the intercooler piping, but in the testing I saw this was never the case. However these were moderate boost levels, with a compressor still well within its map, and on a gasoline powered engine. Lots of other variables.

[dvst8r]

Originally Posted by JasonCzerak

I thought if you sprayed it pre-turbo, you run the chance of wearing down the turbine wheel. kinda like sand,

You do, just like you have a chance at over loading the bearings and seals and over spinning the turbo, when you hit the spray, or have an inadequate wastegate setup.

When racing turbo's are consumables. On the street inject it after the turbo. Unless you are comfortable with it still being a consumable.

[XLR8R]

Originally Posted by XLR8R

pre-CAC/IC water injection via an axial-spray nozzle(s) centered over the inducer(s)

Saturated air will shed heat more efficiently across the heat exchanger(s),

higher viscosity reduces compressor pumping losses, and unsuspended water molecules are centrifugally forced against the compressor housing to increase gap sealing.

No turbo durability issues when sprayed with above method.

Originally Posted by JasonCzerak
I thought if you sprayed it pre-turbo, you run the chance of wearing down the turbine wheel. kinda like sand,

Did you mean compressor wheel?
Plenty of water already transversing turbine...

[Charles]

Originally Posted by dvst8r

Hmm from the clear manifold testing I watched, it all seemed to be more like water vapor then steam. With that being said I don't recall the outlet temps ever going over about 320F and the highest boost pressure was only in the mid 30's (34psi iirc).

My point was that from the testing I saw, it didn't mater if the water was injected before the intercooler or just before the valve, the amount of cooling was the same. There was no evidence to any cooling from it having time to travel in the intercooler piping system, it was all from the state change that happened in the combustion chamber.

I see what you're saying about if the compressor discharge temp is high enough the state change would happen in the intercooler piping, but in the testing I saw this was never the case. However these were moderate boost levels, with a compressor still well within its map, and on a gasoline powered engine. Lots of other variables.

I think manifold pressures reaching and exceeding 70, 80, 100 or more psig will steam the water and remove the issues of water suspension with the water existing solely as a gas instead of liquid.

That is of course assuming the increased manifold pressure doesn't raise the boiling point enough to keep it stable as a liquid.

[ENafziger]

plenum or intake horn injection is fine for smaller quantities, especially if efficient nozzles are used.

Mike, did you have any specific nozzles in mind as being "efficient"? Are the nozzles included with the Cooling Mist kit efficient at atomizing at ~200 psi? Are the Devil's Own micro-droplet nozzles better?

I have yet to find any micron rating on droplet size at xxx pressure...

--Eric

[dvst8r]

For interest sake: Pressure and Boiling Points of Water

Should have been boiling off in the testing that I observed, however it wasn't? Or at least I don't recall it being noted.

[dvst8r]

Or... Maybe it was boiling of a small amount and holding it right to the transition point of that particular system?

But based on the info above it shouldn't have been in the 300's should have been more in the 250's...??? Maybe my memory is off.

[XLR8R]

Originally Posted by ENafziger

Mike, did you have any specific nozzles in mind as being "efficient"? Are the nozzles included with the Cooling Mist kit efficient at atomizing at ~200 psi? Are the Devil's Own micro-droplet nozzles better?

I have yet to find any micron rating on droplet size at xxx pressure...

--Eric

Yes, the nozzles I spec for the systems we build are rated at <50 microns at standard injection pressures (much smaller at higher system pressure, even with pump overhead factored in at max boost).

No idea on the relative efficiency of nozzles used by brand-names you mentioned, though the others' nozzles are visibly different... that's why we started machining our own nozzle assemblies years ago - so I could design around a known quantity droplet size at xxxPSI & flow rate.
(also so the nozzles wouldn't protrude & disrupt the intake airflow)

Since halving a sphere's diameter decreased it's volume eight-fold and surface area by a factor of four, it's easy to understand why droplet size is so important... just like fuel injection - smaller equals both a more homogenous mixture as well as more rapid reaction potential (surface area is where the main interaction between fuel/water & air occurs).

Furthermore, smaller droplets entrained within the intake system are less likely to be knocked out of suspension in the airstream by valve events... that and the wet-flow benefits of our 12-IR manifold were worth an additional 10% HP just using garden hose water.