ZeroBanger

Someone put an idea in my head and now I'm stuck with it (Thanks T-Von). Anyway, this thread asks the question how to eliminate the intercooler on the FD by using a bullet proof water injection system. Please note, this is not about the merits or installation of water injection, for that discussion please see this thread https://www.rx7club.com/forum/showth...1&goto=newpost

we can state for a fact that water injection is far superior than any intercooler could ever hope to be. We can also say that the intercooler is more reliable than a typical water injection setup. An IC setup is nothing more than piping and an IC. A WI system has seleniods, switches, relays, electric wiring, pressure switches, leds, pumps, tanks, water hose, brass fittings, filters, nozzles, plus all the supported installation.

What if we were able to build a water injection system that was very reliable? Currently if you have WI and an IC, the IC is nothing more than a backup incase something happens to the WI (run out of water, etc).

There are somethings that you can prevent. Owning a rotary makes us very careful not to run out of oil, so I think if you run out of water thats your fault. Some company makes Aux fuel cells, some of them could fit nicely in the hatch area. This could give water for a long time and be very strong/resist cracking. Once all of your electrical connections are soldered and secure, th e area I would be most concerned with is the pump dying.

An idea I thought of is to use dual pumps. these can be setup to have different water lines or be spliced into the same line. There are drawbacks and plus to both approaches. for simplicity lets say you share the same water lines. One idea would be that only one pump operates, but you would have a water pressure gauge that monitors the psi. If the gauge drops below the minimum PSI (based on your pump) and you are in boost (you can tell from the pressure switch) that would mean the pump doesn't work and it would send a signal to the aux pump. You can also install an aftermarket air temp gauge/switch such as the one summit racing sells. If it detects an air temp of a pre-set value, it can activate the other pump. It would assume that if your air temps are critical, that the pump is not working. Or it can be setup that the 2 pumps are on seperate water lines and based on critical air temps, the 2nd pump will join in (it would have 2 nozzles of its own). Based on what I have seen and read clogged nozzles are not likely, but there would be maintenance every month plus filters in all the lines.

I would likely have a total of 4 misting nozzles (Maybe 6) that would be attached to the piping that connects the elbow to the bottom IC hose.


Ok, I'm out of idea, have alot of time on my hands and downright crazy. Please humor me. Thanks.

spurvo

What about a progressive pop-off valve that is controlled by intake temp? If you run out of water, the temp goes up, the pop-off vents, and you never run positive pressure in the intake charge. Obviously, you feel this by having the car fall on its face. You could still drive the car to wherever a water source is, and if the problem is electrical, you can still drive it home to fix it, right?

Let see... intake sensor provides a sensing current to a transistor that in turn controls a variable solenoid to control intake pressure. As intake temp goes up, resistance in the sensor goes down, current to transistor increases, voltage to solenoid increases, plunger comes out, intake charge is vented.

Hmmm... need to make it RPM dependent (throttle position, maybe?) to reduce lean out by slapping solenoid closed at decel and idle. Hmmm...

ZeroBanger

What ever we do, it needs to be on the level of the intake charge, I agree. We cant simply base it on a low water indicator in the water tank, due to the fact the pump could be dead. Maybe we can do something like an attempted recovery, if fail shut the boost down, something similar to what you are saying.

This could be done, i know it!!

spurvo

Well, how to shut boost down when in the middle of boosting and suddenly the intake temps skyrocker? Just opening the WG or slapping closed the TC won't be fast enough, you still have a pressurized charge as the turbos spin down. Mechanically driven blow off valve? Kinda what I described above, isn't it?

mjw

iTrader: (1)

My question would be what about partial throttle and cruising conditions where you are not boosting the car? How would the air temps be controlled over a long freeway cruise with no intercooler (assuming you set this up having the WI come on at x-PSI)? Or are you thinking of having the WI running constantly?

ZeroBanger

why would you need it? The intercooler is only in use when you are boosting, am I wrong?

the_glass_man

iTrader: (2)

why not just run methanal? Then there wouldn't be a need for either.

ZeroBanger

agreed, except this is for a daily driven or track driven car. You just cant buy methanol at the gas station conveniently. Again, this isn't about alternatives, the thread is how to make a bullet proof or near bullet proof water injection system, not alternatives.

911GT2

Clarify please? In my limited understanding, the only intake is the obvious one, that feeds directly into the turbos. The air then goes into the IC and then to the throttle body, etc. How is that any air gets into the engine without first going through the IC?

I can see if you said that the IC was only necessary when boosting, but it is used all the time as far as I know.

ZeroBanger

I dont know, maybe I should say that the reason we need an intercooler is because the turbo causes the intake charge to heat up. During normal cruising you would not need an i/c or water injection. Again, I dont know anything so dont take my advice.

bureau_c

I think you're right...intake temps under non-boosting conditions are no different than for any other car. My question is why would you want to make the IC go away...don't the two systems compliment each other? I would think the IC makes a nice backup to a failed water injection system. Are you doing this to eliminate the intake restriction posed by the IC?

Personally, I am very interested in doing this to my car, but not as a means to replace the IC...I'm interested in the idea of getting better-than-FMIC performance out of a stock IC-equipped car. For substantially less money.

jds

ZeroBanger

you have turbo lag and crummy throttle response cause of the IC. Also, you can have an angle mount radiator, cleaner engine bay.

but yes, there is some irony that water injection is designed to keep you from detonating, and if you replace the IC with it, you could cause detonation if there is a malfunction.

Also thing of the pressure drop of the IC.

911GT2

It sounds like an awesome idea. I don't know how practical it would be though. How much water do you go through now with your current set-up?

On a track car I'd say it's probably worth it. Or even if you have a quick pipe replacement for the IC that can be changed over when you get to the track. Personally, I wouldn't want to worry about having enough water all the time when driving on the street.

Then there's the problem us northerners would have of the water freezing in the winter. Not practical at all.

DCrosby

You drive your car in the winter !?


I've said my peace about Water Injection...
But as far as reliability goes, I figured I was going to use the Rear windshield washer tank, and run a water line to the front.. and from what I understand WI uses about 1 Gallon of water / tank or somewhere near there depending on how much you boost... on the track you basically check it every pit...

On the street you check it every Gas / Up
gas up and water up... then go...

As far as pump failure I was going to wire in My Water Injection Like Nos based on MAF and TPS... and then accordingly add water... and if the water wasn't there it would retard sparc and open wastegate... and basically make it N.A....
You can hook up a wire that connects through the water just before it goes to the nozzle, and if the connection is interrupted (Sensor is open, relay closes turbo shuts down..)

And in non turbo air flows through the IC but it doesn't add much cause the air in the IC isn't as hot as the ambient air... only compressed air is hotter than ambient..

cpa7man

iTrader: (2)

I used to run WI on an old piston turbo car of mine, I would run a mixture of 50% water and 50% methonal. Than no freezee.

t-von

iTrader: (8)

Exactly! Thx for he props Zero

Everything about this subject could be very beneficial to our rotarys. Especially the ones living in really hot climates. Hell I live in west Tx and it was 110 degrees last week for two days. Thats a bunch of BS if you ask me! I don't know about you guys but, I can't stand driving my car on hot days like a sissy. Any ways, if you guys have read that link posted above, you should be amazed at Zero's intake temps. Also in another thread he started( about intake temps being to low) I posted an intake temp chart from Sport Compact Car magazine (project Rx7) showing the differances in an intercoolers ability to lower intake temps under hard accleration. The intercoolers used were the M2 SMIC medium and large. The differances in temps were only a couple degrees but, the intake temps were an average of 30 degrees higher than ambient. Zero has a small Blitz IC (slightly larger than stock)and his temps with WI were way lower than the larger M2 IC's in that test. I know a FMIC would have lowered the temps better but, at what cost? More lag? Less airflow for the radiator? More money? Now I don't want to turn this thread into a SMIC vs FMIC war but, it's odvious no IC will ever lower intake temps lower than ambient. Also in addition to what Zero said above, you wouldn't have to worry about heat soak. Plus our rotarys would run much cooler with verticle front mount radiators. With that said, damnit we have to put our heads together and built a near bullet proof WI system .

t-von

iTrader: (8)

Hey Zero, I just thought of something. If this idea works, and that Anti-detination device from KDR lives up to the hipe, you would have to change your famous quote from "The -7- Can't Lose" to "The -7- Has No Equall"! Ha ha ha ha

DaedelGT

One thing I'd like to throw into the hat. When you get off boost, the turbos are still extremely hot and even though the air isn't as hot as it can ge,t (200° +) it's still going to be way too high for safety. I think you'd need a third nozzle that would run regardless of boost, based entirely on intake temps, to cool down this extremely hot air. Maybe have it turn off when boost pressure is reached so you don't have to recailbrate the other two.

If you had brought this up in a semester I probably could have done the equations for you. I'm not sure how much of the heat from the turbos (really really ******* hot they are) actually gets transferred to the air flowing through them. They are always at a minimum of your water temp.

Cannonbear

i'd always heard that shorter IC piping would reduce lag and improve throttle response. So in theory if you could redirect IC piping (be it side mount or front) you would have less of each and the WI would be more beneficial.

I know i didn't state anything groundbreaking, but i've seen some of the IC kits out there and its like 6ft of piping where 4ft would do if some organazation took place (as well as cutting).

Im not sure how much room you could free up, but even some inches of shorter piping would help!

t-von

iTrader: (8)

I've too thought about that situation before but, that can be easily overcome with proper placement of the WI nozzles. When I do this to my car, I'm going to place the nozzles as close to the turbo outlet as possible. This way during boost, the water will inject immediatly cooling the hot air along with the piping. This will also allow the air to fully cool before getting to the throttle body(less water vapor in the UIM). Now during this "off boost" situation you speak of, the piping would have already been cooled down substantialy from when the car was previously boosting. Therefore, the accual piping could help provide some temporary relief. Also you could rig up some sort of timer to run the WI a few seconds after boosting.

racerfoo

You could also put some sort of sending unit in the water tank...to give you a "Low Water" light like in fuel tanks. That would be easy depending on the tank used.

Also, if you are using a 2nd pump for a backup, the secondary pump should be hooked up to another LED type light so that you know you're running on the backup pump, and you need to fix something.

i like the intercooler possibilities now....SMIC, FMIC....and NOIC

DaedelGT

racerfoo, I believe the low water level sensor is coming in his set up and the 2nd pump will have its own on switch/LEDs.

t-von, it's not nescesarily the piping to worry about, but the turbos. They are always going to be hot. Maybe we can get zerobanger to measure his air temps right after the turbos after crusing for several minutes off boost. Cooling down the piping after the turbos will only help so much. I guess we shall have to wait to see

bureau_c

I guess I'm still a bit paranoid at the thought of eliminating the IC entirely. However, I can certainly see how this could drastically change the definition of the perfect IC for our cars. The ability to drop temps goes way down on the priority list, since its really just a backup device to WI, and the most important thing becomes finding the solution with the lowest pressure drop, best flow, whatever.

That's probably fodder for another thread though...
jds