[rotrex]

Point is that the water mainly acts in the chamber or to a degree the compressor.
It needs heat to evaporate. Lots of it. as the the droplets cool down due to evaporation and the water's vapor pressure is rather low and drops with temp, water does not evaporate fast unless you provide lots of HEAT.

This is static effects (heat of evaporation) vs. dynamic effects (heat capacity, vapor pressure vs. temperature).

Intake air cooling in the pipes is a minor effect. Folks have tried that for decades.
the temp readings barely change.

issues like water replacing air reducing power is akin to "running rich costs power as it replaces air". It is a minor downside compared to be able to run at MUCH higher boost than without and/or getting higher cylinder pressures from more ignition advance. -> more power.
You lose a few percent of potential power and gain several times that as real power.
A turbo increases backpressure, hence costs power. As you know, that is only half the story.

shoving the maximum amount of fuel and air into an engine is only one part of the story making power. You also need to be able to extract this energy and convert it into mechanical power. This needs optimum ignition timing to achieve max. cylinder pressures at the right point in time.


What you try with humidity sensors and some cooling is like trying a different cone air filter brand to gain more power. The effects are negligible compared to water or w/m in the chambers.
You ignition will have no issues unless you flow massive amounts of water.
In my engine this was at about 600cc/min pure water. Adding a tad of dwell time in the ECU in the area of the map fixed even that.

If you use methanol in your mix or pure methanol, that all changes.
Methanol has a lower vapor pressure and lower heat capacity. it evaporates much faster given the same temperature environment is provided compared to water.
Energy per time unit is cooling power. As more methanol evaporates per time unit compared to water, it tends to cool the air more in a intake path. In the chamber itself or in the turbine, the difference is of less importance as these places are a much hotter environment.

The chamber is water or methanol flow limited in most cases regarding how much they can evaporate and how much cooling you can achieve.
More fluid= lower air temp in cylinder (where it counts the most) = more power.
Of course there is a limit for a given IAT and compression ratio. At some point, it will flow out of the exhaust. The WW2 engineers tried that, too.
If you stick to the here recommended 10-20% water to fuel ration, this is of no issues. If your boost goes above 25 or even 30 PSI, you can add much more.
See RICERACERs RX7 development. His engine works in the same extreme regime as did the WW2 aircraft engines. The more w/m he adds, the more boost he can run and the more power he gets from the engine.
In his high boost setup with pre compressor injection, the IAT reduction is much more pronounced and an important element to gain big HP numbers.

you can take w/m to the extreme. Just add more boost and more fluid.
You are essentially only limited by the mechanical strength of your engine. 100PSI boost in a 1.5l 4-pot. That's what BMW and others did in the 80s F1 engines getting 1000+HP.

The boost pipes are energy limited when it comes to water evaporation. There is not enough heat to evaporate all the water. The droplets plainly become too cold to further evaporate. This is actually nice, because now they can make it where you really want to have them, in your engine.

the aquamist system in the WRC cars worked so well with pure water because the turbos were used at insanely high pressure ratios producing extremely hot charge. This was caused by the intake restrictors required.
And even they used direct port injection. They did not care about cooling in the pipes. They (and we) cared about cooling the charge in the cylinders. Even more specifically, you care about cooling unburned charge in general and eve more in the area of pressure or shock waves while the flame front advances to prevent spontaneous ignition aka knock. Shock waves compress the charge heating it further. Droplets evaporate faster, cool the mix and by that reduce the pressure. It dampens pressure waves. It also slows heat up at the flame front. Thats why it slows flame speed.

The music plays in the cylinder. It is just not that easy to get it there in a uniform way. This is where all the discussions from nozzle location come from. It is a lot about practicality vs. complexity.



The turbine can also evaporate a lot, if pressure rations are high or efficiency low.

If you use plain water, try a intercooler or charge cooler first.
Your cooling to the due point is not worth the trouble.

I have used a Rotrex C30-74, now replaced by a C30-94, with various nozzle locations and mixes.
non-intercooled I saw 100C IAT with 0.6bar of boost. just look at your compressor maps and do the math.

Injecting water does very very little to change the IATs. Maybe 20C.
Injecting methanol before or after the compressor has more dramatic cooling effects. The most extreme for me was 300cc/min 50:50 water methanol pre-compressor injection. I saw IATs actually dropping to ambient temps as boost was climbing.

I cannot see you getting only a 10C increase in IAT over ambient at 1 bar of boost without charge cooling and only minor post compressor water injection at 200g/sec of airflow.
There is something wrong or missing.


Once you use serious amounts of water that actually makes it into the combustion chamber, droplets do not like to take tight turns e.g. in a plenum with bend runners, all those factors like humidity and even intake air temp become of less importance.
See it as your cell phone playing music in the first row of a rock concert. it will make no difference to the audience.

If you want to make significantly more HP from your setup, especially without charge cooling, you need to get the water into the chambers, lean out the mix 12-13:1 and advance the ignition close to best torque or the knock limit.
if you hit the knock limit first, add more water/meth and further advance the ignition.

In the end, I now use direct port injection with 4 75ml/min nozzles 2" before the fuel injectors. Fuel i complimented by 4x 440cc/min injectors.

For the ignition, I am still knock limited, I found that up to about 60C, IAT plays little role to ignition timing. I only pull serious timing past 70C. Before that it runs really well with a particular aggressive sound.

Ignition timing at peak torque is about 23? without WI and 29? with WI, both at 0.7 bar and 6500 rpm. Engine a build 1.8l Rover K with a 8.5:1 CR in a Lotus Elise.

Mapping the same engine without WI, I can't remotely achieve similar power levels.
The engine is charge cooled, but the pre-rad is currently too small. That does not help.
A new engine radiator sized pre rad is already sitting in my basement, but the car is away in winter storage until March.
Together with bigger lines and a bigger pump, IATs will drop.
This will allow me to extract more power without WI, but also with. The gains are just lower.

Try adding more water/meth and map for it. You will be surprised how well it works.

Pure water in my experience leads to rather slow (initial) burn speed requiring you to use a lot of ignition advance. This is harder to tune.
Adding 50% (wt) methanol compensates that to a degree and makes it easier to tune. The slope of ignition advance vs. power gain is more steady with a smoother transition to knock in my engine.
At least it does for a low to medium boost engine.
Once things are really hot in a 30+PSI engine, this is less of an issue.