Monsterbox

iTrader: (6)

Does the temperature of the tank fluid have any significant impact on the knock protection/octane benefits of either straight water or 50/50 mix?

Contemplating utilizing water from the same tank as water-to-air intercooler tank in the trunk of the car, but this water reaches nearly 100+F. I would imagine this physically cannot reduce the intake air temps any lower than the temperature of the water, but will the injected water still act as knock protection?

FührerTüner

iTrader: (5)

Other depending factors could be whether youre spraying pre or post turbo/intercooler

Sgtblue

iTrader: (16)

Time of contact, area of contact, and temperature differential are factors. But if you're talking ONLY water, it needs a lot more of each to effect IAT's.
Still, intuitively even hot water introduced into the combustion chamber will have knock suppression and a cooling effect on the engine. The combustion chamber temperatures will still cause the water to go through a phase change from liquid to vapor and it's in that change that it absorbs heat and suppresses knock.

BLUE TII

iTrader: (9)

Slightly different application, but interesting story.

I did a test at my local hillclimb on cooling off the outside of my intercooler.

The hot water spray cooled the IC down much much faster than the cold water spray.

The hot water evaporated faster allowing me to put more hot water on which evaporated faster. Evaporating hot water off a hot IC still leaves you with a cold IC.

Much energy required for the phase change.

To apply to water injection.
Should be able to inject more hot water into the intake than cold water, so should have the same effect of more cooling.

At some point, more total water injected means less room for air and fuel which means less power.

I have read the volume of water you want to inject is 12.5% to 25% of your fuel volume.

From this site-
https://www.rbracing-rsr.com/waterinjection.html

WANKfactor

iTrader: (1)

two words; evaporative cooling.

rotaryfreak3

Not unlike this commonly observed effect: https://en.wikipedia.org/wiki/Mpemba_effect

Sgtblue

iTrader: (16)

No...don't think so. But in a way, you're asking two different questions. The knock suppression value of water-only takes place in the combustion chamber during phase change from liquid to vapor. Lot's of heat there to do it. It also cools hard seals and reduces carbon...which can also lead to pre-ignition.
As I understand it, if only water is used, to have much (maybe efficient is a better word) of an effect on IATs it needs introduction earlier...at least pre-IC. Or as Blue TII mentioned, used as a spray on the IC for evaporative cooling. Water temperature isn't critical. An ALCOHOL mix is more effective at lowering IATs and needs less time of contact. But the alcohol has less effect on knock suppression in the combustion chamber.
Pre-turbo, pre-IC or IC sprayer usually requires a big reservoir and usually more sophisticated management.

Monsterbox

iTrader: (6)

Thank you for the info guys.

So I'm listening to everything that's been said here.

And thinking...

May just run 500-750cc of straight water, right into the compressor housing outlet, so that it evaporative cools the hot charge piping and the intercooler inside the intake manifold, which would then take the load off of the intercooler as the hot charge pipe will have been pre-cooled closer to atmosphere right? Then as you guys are saying, the water itself, will then travel into the combustion chamber where it further protects against knock during its phase change.

The pump will be the 200psi coolingmist pump, and spray nozzle with a check valve on the tip, and Ill just have a relay triggered on/off by the ECU at 2psi MAP pressure. The water will be drawn off the 2 gallon metal tank in the trunk which currently houses the pump and water supply for the w2a intercooler system. This way no extra tank needed and could just top it off regularly?

So am I understanding this all right that it should all work?

Sgtblue

iTrader: (16)

Off-hand you'll also want an in-line filter before the nozzle. Any of the AI suppliers offer them.

BLUE TII

iTrader: (9)

I think your intercooler will be most efficient with the highest delta (so biggest difference between intercooler/air temps and water temps), so you should spray post IC.

I always see the people saying pre compressor or post IC, but not in between. But I don't have any experience with water injection myself, just what I have read.

Shainiac

iTrader: (7)

I would inject post-intercooler. The knock protection comes from the change of state from a liquid to vapor, in the combustion chamber. If you inject pre-intercooler, there's a good chance it's hot enough to change that state and cool the air, doing the job of the intercooler. Yeah, that's not a bad thing, but you won't have as big an effect in the combustion chamber if most of the water has already changed state.

As for using the same reservoir, I would not. I would also not run 100% water in the intercooler. After 6 months, the distilled water in my intercooler smelled horrible! I pulled the hose off the heat exchanger to remove it and got blasted with pressurized, rancid water from all the bacteria and critters growing in the water. Run a little anti-freeze or add a couple drops of bleach periodically. My garage smelled like dead animals for a week! You're better off having a tank just for injectant and adding a level sensor so you can have failsafes if the tank runs dry. I did this and it saved my *** more than once. And my motor was A LOT cheaper to break than yours

Howard Coleman

iTrader: (6)

no.

the benefits of running water relate to the latent BTUs of cooling. whether the water is ambient, say 80 degrees, or engine compartment temp around 140 will have very little influence on the actual water density.

while it may work just fine, i am not a fan of pre-turbo AI. water is a very heavy substance, around 8.5 pounds per gallon. the compressor is aluminum, finely shaped and spinning around 100,000 RPM. i just don't like the dynamics. i also don't like clogging up the IC w anything but air. finally, i would rather used the latent heat in the combustion chamber where it counts.

water does a great job in the combustion chamber both from resisting detonation and cleaning the internals. an easy location for your delivery might be the silicone coupler just in front of the elbow.

Howard

Monsterbox

iTrader: (6)

Awesome thank you HC!

Will definitely proceed with the installation of water injection for this setup.

wish I could go post intercooler, but the intercooler is integrated into the intake manifold, which is all post-throttle already, so there wouldn't be much room for the water to diffuse across the 4 intake runners. So I think it will end up best mounted on the compressor housing oulet right before it couples with the charge pipe

BLUE TII

iTrader: (9)

Individual port water injection is actually a desirable set-up if you want to spend the $ on the extra nozzles/check valves.

You can check out the lengths these guys went to for their LSR bikes.

https://www.rbracing-rsr.com/waterinjection.html