Those intercooler sprayers spray water on the intercooler. Not into it.

 

Yeah, I corrected my statement. You are just mad fast.

 

Knowing absolutely nothing about water injection, I'd expect you'd want the water nozzle as close to the outlet of the compressor as possible, give the water plenty of time to change phase and soak up heat.

And IAT always goes post intercooler, either endtank or plumbing directly after endtank, outside engine bay. As expected, Aidans test shows that in steady even air temps the case of the sensor will skew temps bad. There's nowhere else you can put it.

 

the water will provide biggest effect inside the combustion chamber
and I wouldn't want it cooling down the sensor anyway, rather be running too safe than artificially "safe"

 

Based upon studies done by NACA (the predecessor to NASA) during the 1940s, the optimum place for the water nozzle, in terms of combating knock due to insufficient octane, is inside the combustion chamber ala direct-injection.

This is hard to do.

 

I believe in the runners is the second best place. From my minimal water/meth injection research. Look up direct port meth injection.

 

The key point being simply that the water does most of its work inside the chamber during the compression cycle. Relatively little evaporative cooling occurs in the intake plumbing or the plenum.

You want as much of the water as possible to still be finely atomized when it enters the chamber. The further upstream you inject it, the more likely it is to pool out of atomization into larger droplets, especially if an intercooler is present.

 

yup, exactly where I was going with that

that's why I'm always a bit surprised (and skeptical) when people claim their AIT's magically plummet with w/i and no intercooler

 

Well the water probably cools the sensor...

 

and they think their charge is legitimately below ambient

 

My GM IAT is in the cold side of the intercooler and my water/meth injection is about 6" from the throttle body.

I'm sure water is probably ok to spray in front of the IAT sensor, but I have a feeling meth probably isn't that great of an idea.

When I'm spraying meth on the streets, I run a special tune for it. And when I'm running only water like at the track, I run a much more mild tune.

 

you dont e-cool?

 

how exactly would that work?

 

I d-cool

 

^He actually V-cools but he has a thick accent.

 

Evaporative cooling on the sensor element? Just spitballin here

 

I would be concerned about measuring the air as being warm and then having it actually be cooler and more dense once it is then cooled by the injection. This could inadvertently make the mixture more lean.

 

hmm, so basically it sucks either way.

got it

 

unless it's pretty much repeatable and consistent. then the fuel map would just reflect it.

 

Again, there's very little cooling effect happening outside of the combustion chamber. I don't have the data in front of me, it's somewhere in a binder at home full of old photocopied test reports from WW2.

Any cooling (and thus, density increase) which happens inside the chamber during the compression cycle is irrelevant from the standpoint of fuel metering, as it's a sealed volume. More oxygen cannot enter past the closed intake valves.