...Edit: Oh, specs for the intercooler...
188 mm wide, 210 mm tall, 88 mm deep
12 rows of fins 205 mm long with 115 fins each, aka ~14.25 fpi...
the biggest problem is cooling a very large volume of air very quickly. Assume surface area of 1ft2
60 mph = 100 ft/sec
x 60 sec = 6000 cfm
this is about 1 lbm/min of air passing the intercooler @ 60 mph at STP (less at altitude)
It all comes down to how quickly you can cool 100ft2/sec @60 mph for example. And then you still have air close to ambient, and it's still air. 0.001225 g/cm3 vs 1 g/cm3 for water
I did post the frontal details of the intercooler though. With 25 equal segments across the intercooler face, 12 of which will let air flow through, we have ~29.4 in^2 to work with, which gets us ~1167 cfm @ 65 mph with the engine turning over at 2500 RPM +/- 21 RPM. On the stock camshaft, the VE is in the neighborhood of 86% from the data I have.
However, there is the limitation to the ducting as the opening is only about 19.4 in^2 so I'm not sure how to determine the amount of air passing over the intercooler.
and everyone who has ever taken a thermodynamics class in college knows mc delta t so even if c is the same for water and air (which it's not) then air is already 1/800 as effective as water so even if you managed to cool it a couple degrees is how effective...
If you kept the intercooler wet maybe more effective, but then why not have air/water IC at that point. When I did these experiments it was most effective if you drenched the intercooler but the drag strip did not like that at all.
It's a good thing that even at 60 ml/min, the frontal area of the intercooler is saturated then, no?
...
I know how much coverage I have due to a wet intercooler 
. After nozzle placement is adjusted and tested, I'm going to bump down to the smallest size to see what the effect is. Currently I'm seeing about 2-3 °C drop in IATs at 75 mph max but a better cool down time after boost is evident too...
On that point, I went to town on cleaning the intercooler and given how slowly water "drains" from the fins due to adhesive forces, It seems that now quite flooding the IC, but keeping an even coat of water is fairly doable. More on this in a sec.
Psychrometrics, a topic I've been acquainting myself with since I started this.
A fine mist spray into hot dry air will very rapidly cool the air down, at a diminishing rate as the air approaches saturation. The rate at which the water evaporates is based primarily on the surface area of the interface between the water and the air and the dryness of the air (the amount of water the air can absorb). Water collecting on the surfaces of the intercooler, where it would pool into larger droplets will not evaporate faster than the actual mist would. At best, if you have enough stay time between mist entering the hot dry air, and the humid cool air hitting the intercooler, you are looking at getting the air temp down to about 5-7 °F above ambient wet bulb temperature.
Ideally, instead of spraying water onto the cooler, you probably will get better effect, and certainly better use of each ounce of water, by spraying as fine a mist as possible into the incoming air charge - if you can duct this air to make sure you get all the cold humid air you are making over the intercooler, that's even better. Spraying the mist INTO the wind (away from the intercooler) would also increase the stay time, as well as increase relative velocity between water and air.
In a ducted mist or steam humidifier, the mist or steam is most often sprayed upstream in the duct for this very reason.
Your statements come out to ~2.8-3.9 °C. This matches up, generally with saturating the air to 70-80% relative humidity, which happens to be where I was expecting diminishing returns. Thanks for confirming.
I extended the nozzle out about 3.5-4", ball parking because I didn't measure the pipe extension. After getting home from steady-state testing, et al, with no more than ~70% relative humidity, I'm quite happy with the results. The back of the intercooler was visibly wet on all but the upper-inner corner, the hardest place for air to travel to from the ducting setup. I'll aim the nozzle about 10-15° higher for the rest of the resting, though it seems that I have no less than 90% coverage at the current state. At least for sub-60 mph driving, which is about the final 2 minutes from the freeway to my driveway,
60 ml/min of flow @ 19-20 °C w/ 70% RH is enough to saturate the surface of the intercooler. My tire was completely dry though. I'm seriously considering switching to the smaller nozzle to see if I can get evaporative cooling.
I did a steady-state test tonight. I'll have the log/graph posted up by 0130 PDT. There is a definitive difference between the sprayer on and off even for a pressure ratio as low as 1.2-1.3. I couldn't get to ambient temps under these conditions, though that I suspect is likely a result of having the water settle on the intercooler and not readily evaporating. Truth be told though, I have a mixture of water, isopropanol, and a light chemical cleaner for the aluminum so I wasn't dealing with a known ratios of fluids with specific heat capacities. The server has about 6-ish min before the email routines render it inaccessible, next post from me will be a graph of the log.
