spraying 50/50 through SC and A/W IC?

[FI_Rubicon]

Has anyone run water/methanol 50/50 through an air to water intercooler? What are the long term effects and has anyone actually killed an intercooler with water/methanol spray?

I do not plan to use more than 50% methanol and this is a supercharged street car. I also understand that methanol (100%?) is corrosive to the aluminum heat exchanger but am wondering about 50/50.

[rotrex]

I do not expect any long term effects on the CC alloy. Exposure is very limited and the water context reduces the reactivity dramatically.
So unless you spray a lot and tend to stop your engine a fraction of a second right after a WOT run and then store it for a few months with everything on the inside being wet, ö thing will happen.

A much bigger issue is condensation. I have observed this myself in my set-up. Past a small amount of pre compressor spray, I have logged air temperature fluctuations and sudden changes in the applied ignition correction over air temperature. This can be attributed to liquid methanol / water droplets evaporating on the IAT sensor after the CC.

If you want to spray lot's for fluid through a CC, you likely need to do two things:
Increase the methanol content of the mix as methanol evaporates much faster again. Even big droplets eventually evaporate in the cylinder as any other fuel.
Second, try to generate as fine of a mist as possible, e.g. Through a air assisted nozzle.

The hotter the environment you run and the worst your CC works, the less of an issue you have with condensation. Riceracing's set-up is a nice example of a suitable combo for pre-compressor injection: toasty hot Australian weather, small factory intercooler plus high boost and flow.

Unless your setup fulfills those criteria, you are likely better off injecting post CC and/or direct port.

Smaller droplets are better. Droplets size drops with increasing fluid pump pressure for hydraulic nozzles. Properly designed jets should not show much different drop sized with their size, although the the very small ones with their small offices tend to produce the finest mist.

The more extra power you try to extract with the injection system, the more critical distribution gets. The cylinder getting the least mix will be the limiting factor.
The more methanol you inject, the less critical droplet size gets as even puddles and streams evaporate.
This is why I believe many folks get good results with more methanol.
Efficiency though smaller droplets can most of the times be compensated by more flow.

[FI_Rubicon]

Thanks for the info. The rice racing system seems interesting and I will look into it. I have not been into rotaries for years but am a former factory trained mazda/subaru tech. Back when I was playing with rotary cars, the only vendors were basically Racing Beat and the next runner up was Rotary Engineering (now defunct).

Interestingly, this is a jeep so it has an onboard air compressor already - also from Australia. It is a twin pump model designed for continuous use and filling up huge jeep tires. Maybe I can connect the systems together.

In searching around for air assist, I stumbled onto folks doing some sort of hydrogen injection with I think vacuum assisted nozzle. Interesting.

edit:
I have this aFe filter that has an inverted cone. I have enough real estate inside the cone to put a jet in the center aimed down the intake tract.



I don't know if this helps or hurts but the intake tract itself is 4" and I was thinking to bring it down to 3.5" or 3.25', which is closer to the stock size of 3.14".

Would leaving the larger size before the throttle body slow the charge and give it more time to atomize?


There is no room with my setup to really go port injection. I will take a closer look again later but I doubt port injection would work for me. I think I have to go 100% pre TB/SC/CC.

[rotrex]

the time in the inlet pipe before the compressor is largely irrelevant as most of the evaporation happens during the hot stuff, so in the compressor itself and then in the cylinder.
Adding a Millisecond here and there makes hardly any difference.

[FI_Rubicon]

Originally Posted by rotrex

the time in the inlet pipe before the compressor is largely irrelevant as most of the evaporation happens during the hot stuff, so in the compressor itself and then in the cylinder.
Adding a Millisecond here and there makes hardly any difference.

Thanks. I think RichardL mentioned that the farther in front of the SC the better. Should I stick with mounting jets perpendicular to the air flow? I was thinking to add one to the top of my cone air filter to spray directly down the intake tract.

[rotrex]

The methanol evaporates very quickly generating smaller high water content droplets.
Water only evaporates rather slowly in the seconds time scale at low temperatures. It only hits the millisecond evaporation time scale (for the fine mist we talk about here) once temperatures get got, so in the compressor and then ultimately in the cylinder.
What counts most IMHO for any spray going though pipes before a turbo compressor is not having any ridges where water can accumulate or puddle. Turbines do not like big drops.
Between my pre compressor jet and the turbine is just one smooth pipe.

[FI_Rubicon]

Thanks. Yes, I currently have a couple of ridges, including a small one where the silicone coupler goes over the throttle body. I need to tune-up my intake tract to make it smoother and straighter.