Engine/Transmission (1994 - 1998) Intercooler vs Intake Manifold Air Horn Water Injection Nozzle Mounting

[MMcCallie]

I'm about ready to add a second water methanol injector nozzle. I bought a 12 GPH 760 CC/M outside thread nozzle from coolingmist.com. The one i now have in my intake horn is fairly small, don't remember but guessing around 6 GPH. I haven't seen as much EGT reduction as i want in the mountains and since i'm now making more power and still smoking at WOT, i know i could use more water. Seat of the pants feels like just 40 hp as is.



A few diesel performance people have told me i should install this big injector in the boost tube just before the hot air enters the intercooler. Some folks i've talked to (who have no experience with water injection) have enjoined that water droplets might cause blockage and restrict airflow. Can anyone verify that this restriction would indeed occur?



My thought is that cooling the air sooner, before the charge air cooler, could help reduce the air temperature the fan is pulling through the radiator. Does anyone have experience with installing nozzles both in the intake manifold and before the intercooler? Where will i see the most cooling and power?



I was just reading a magazine article in which there was a nozzle mounted between the compound turbos. If the hot air can evaporate the water mist within inches between turbos, i'd think it would cool and densify effectively flowing through the intercooler. Any tips before i tap tomorrow?

 

[DPapworth]

My gut feel is telling me that adding water/methanol before the intercooler is the wrong direction. The dominant effect of water injection is to broaden and flatten the deflaggregation (temperature/pressure) curve in the combustion chamber, through the interaction of liquid water droplets and the advancing flame front. The charge air cooling afforded by evaporation in the intake tract is helpful, but it is a much lesser effect.

You need to get the droplets of water to the combustion chamber for the dominant beneficial effect to happen. If you induce water ahead of the intercooler, it seems to me you risk having the water simply condense out and collect in a puddle at the bottom of the intercooler, potentially creating little more than an intake restriction and doing nothing for EGT.


This view is supported by the fact that the manufacturers are experimenting with water injection using the fuel injector itself, rather than the simpler tactic of introducing it into the intake air stream (they call this latter tactic "fumigation"). You can read an academic discussion about these issues here:
http://homepages.cae.wisc.edu/~rutland/research.dir/NOx_water/2000-01-2938.pdf

Another website explicitly states:
"Don't flow water through an intercooler". It can't get much more crisp than that. You can read that material for yourself here:
RSR Water Injection Calculator

 

[Jim Fulmer]

I wouldn't shoot water before the intercooler either! Way back in 03' when I started Matt Snow in this Diesel thing that is exactally what he told me too.



What you want to do is let the intercooler do all it can, meaning let it pull as much temp out of the air as it can.



Now if your running N2O shooting all or at least the biggest shot before the intercooler is the way to go!



Jim

 

[MMcCallie]

Should i just mount both in the intake manifold? The first one is along the back side before it bends down into the engine. Should i mount this one any differently?

 

[RyanB]

Not sure if this is only for a pulling setup or not but Van Haisley told me if I was running an intercooler on my engine setup to have a nozzel as close to the small turbo as possible before the intercooler. The increased heat in the air will turn that water into total gas faster than it would in cooler air. Now this is NOT with a Snow or simmilar system, its with one of the real Truck Pulling water setups which puts out 500psi so that might make a difference as they also say to inject water between the turbo stages!



One thing I have often wondered is if an intercooler is more efficient at different temperatures. Say for instance in comming air was 500 and it dropped to 400 and say with cooler air comming in at say 350 and it dropped to 200. Make any sense? just curious.



RyanB

 

[DPapworth]

The hotter the incoming air temperature, the more heat energy the intercooler will remove. As with other heat flow processes, and as the second law of thermodynamics teaches us, the system efficiency improves as the absolute temperature difference increases. In this case the temperature difference is between the charge air flowing through the intercooler and the cooling air being drawn through the fins by the fan.

So the hypothetical performance numbers posted above by RyanB are backwards from reality -- the temperature difference afforded by the intercooler will be greater with a hotter incoming air temp.

It is perhaps plausible that a 500 PSI nozzle placed between two turbochargers could obtain complete atomization and maybe even complete conversion of the incoming water/methanol into steam. The latent heat of evaporation would certainly contribute to charge air cooling, but it isn't clear that inducing steam into the combustion chamber would have the same beneficial effects there as would transferring water droplets. How do the
two effects trade off? Not clear. A worthy area for experimentation, computational fluid dynamics, and dyno runs.

But I think that if you have just ONE turbo and a low pressure water nozzle, there is little question that adding water before the intercooler is a bad idea. Too likely to end up with a puddle of liquid water, among other issues.

 

[MMcCallie]

Thank you for the inspired responses. I am running a plain Snow pump with a Coolingmist controller. I don't think i'll be needing super high pressure since this is a daily driver and i have yet to add my HT3B so i'm single for now. Thank to the advice in in this thread, i will not inject pre intercooler. Does anyone have a suggestion as to where exactly i should add this second, giant nozzle or is anywhere on the intake good?

 

[Jim Fulmer]

View attachment 65165



This way always seems to work just fine with that system!



Jim