Dragon

Ex temp will go down with the water injection. The Denser ex gases that now have water vapor in them will help to push the turbo wheel and cause it to spool faster since it is being hit with more inertia

little rotor

So is there a noticable difference? From data logs can you observe a given boost pressure being achieved at lower rpm? Please give us some numbers to help put it into perspective.

epion2985

thanks Dragon. I have a question. Say you are tuning a new rebuild engine. You start rich like you said and work your way down watchung the temperatures. Now say you hit the sweet spot. Now you want to add water injection (someone above said tune first then add water injection to avoid hydrolock and other probelms) so you add it and it drops your temps. Now 2 questions. One being I assume you can cut down on fule now since water injection is cooling things quite a bit, right? And two, with water injection which is a better way to controll it, with a sensor that monitors boost, or with one that monitors the temperature in the intake manafold?

Dragon

I'd tune with just gas and no water injection to around 1kgcm or so, then put int the aquamist kit and have it start to inject water at around .8 kgcm of boost using the .7 jet that comes with the kit. Your O2 readings won't change with the water injection and you can still tune fine with it on or off even though the ex temps will drop some. How you do it all depends on what final boost your going to run and what turbo you have, intercooler etc...

ZeroBanger

its simple. You have 2 options.



1) tune for water injection.

2) Tune for your IC.



For option 1, You need to realize that with the Water Injection on, the intercooler is doing nothing more than causing pressure drop and lag. you dont need it except if the water injection fails. At any point in this car if you only tune for water injection and it fails, you are screwed. its very possible to have a very reliable water injection system, but you need to make sure its reliable.



for option 2, this is how I am currently set up. My car has enough fuel for 16 psi, but my Blitz smic is small so without the WI I could likely only support 14 psi or so. What happens if I got a bad tank of gas? I'd likely detonate. So I only ran about 12. Now I dont need to worry. I now run 14 psi on pump gas with no issues. I figure the chances of a bad tank of gas and water injection failure are nill.



BTW...I wouldnot run more than 14 psi on stock twins. If it was not for that I'd easily be running around 16 psi on pump gas.



Later.

Dragon

There arn't 2 choices. You NEED to run your intercooler with the water injection. your intercooler cools the air and the water injection further cools the air a little, but cools the internals of the engine a lot. The water injection doesn't do **** until you acive a set boost pressure and before that the intercooler needs to be doing it's job. As boost rises the air charge gets hotter so even with the intercooler you outlet air temps will still increase. The water injection will help get them back down to what the were at the lower boost levels. Water injection doesn't replace the intercooler, it just makes things even better.

ZeroBanger

You do not need an intercooler if you have water injection. sorry, Im running around with sub ambient air temps, my puny blitz SMIC does ****.



I see lots of cars that run without an IC (MR2, etc) an rx7 is no exception. I will someday run only on water injection.

ZeroBanger

Your engine and your $, so you can go ahead and do that if you'd like to, but I would recommend perhaps you should just go out and get a real intercooler before you even think about putting in water injection. [/quote]

dude, I have had my water injection for about 2 months of daily driving, I have had my intercooler for almost 2 years.



Your opinion is one thing, but dont tell me how to set up my car. An intercooler is only a a back up for the water injection because its reliable. It serves NO other purpose. its not that hard dude.

Dragon

I'll guarantee you that your puny blitz intercooler as you state is doing something. With out it you'd probably see +20'c intake air temps. Anyway it's your engine and your $, so you can go ahead and do that if you'd like to, but I would recommend perhaps you should just go out and get a real intercooler before you even think about putting in water injection.



And those lots of cars you see running around with out intercoolers knock one and keep running. RX-7's tend not to survive a good knock, so it is an exception.

Dragon

Your engine and your $, so you can go ahead and do that if you'd like to, but I would recommend perhaps you should just go out and get a real intercooler before you even think about putting in water injection. [/quote]

dude, I have had my water injection for about 2 months of daily driving, I have had my intercooler for almost 2 years.



Your opinion is one thing, but dont tell me how to set up my car. An intercooler is only a a back up for the water injection because its reliable. It serves NO other purpose. its not that hard dude. [/quote]

Ok, and how much power are you pushing and what turbo are you runing.



Edit. I saw your sig.. hmm two craked apex seals eh. an you were pushing a little over 300 before that. Umhmm I don't think you need to even worry about water injection yet. You see this is the single turbo forum where most people are looking for over 400 hp+. I've had my water injection for over a year now and I've been buiding 13B's now for 5 years and I was boosting 1.6 with a T-70. But I see you know best..