-water Injection-
08-28-2003, 06:10 AM
#11
Senior Member
Join Date: Jul 2001
Location: Tulsa, OK
Posts: 3,346
You'll still need and intercooler. Waterinjection is good for two main reasons. It will allow you to run more boost safely or more advanced timining safely. This is of course a result of the intake charge temps being reduced by the atomized water. And of course it would help improve the overall reliability of the car if you left the boost and timing the same as it was before the H20, but wouldn't effect horsepower.
08-28-2003, 10:37 AM
#13
Senior Member
Join Date: Sep 2002
Location: bay area
Posts: 235
I have a huge write up on this thead:
http://www.rx7club.com/forum/showthread.ph...water+injection
IN a nutshell, I find that my air temps are from 20-32C on a hot day with the WI and it pulls hard as hell even when its 100F outside. I have one nozzle in my elbow pointing 90 degrees down the pipe (toward the hot air) and one in my intercooler end tank. they come on at 8 psi. I have a 2 gallon water tank that lasts a long time. Cost for a single stage setup is about $140, a dual stage like mine runs about $180 for the parts.
Injector and selenoid 1
A view of both the injectors, the other is in the endtank of the IC, you cant see but the other selenoid is mounted behind the IC:
pic of the water tank and the pump:
considering it does the following:
1) steam cleans your engine, sparkplugs and exhaust eliminating carbon deposits.
2) gives sub ambient air temps, therefore advancing your timing.
3) allows you to run more boost than you could without or gives you a huge safety cushion with your current set up
4) car no longer feels like a dog on a hot day.
5) no more heatsoaking or power loss between 1/4 mile or dyno runs. Ok, to clarify you are sitting in traffic for long time in hot weather...your intake sensor will get heat soaked, but as soon as your boost the air will be cooled before it enters the combustion chamber which means that while heatsoak technically exists, it is not relevant because the air is cooled before reaching the engine.
6) my car doesn't backfire like it used to in hot weather. when my intake temps get hot my car back fires upon deceleration, no more.
7) I Could run 87 octain and/or remove my IC and run only water injection.
8) in my case, my car is set up to have enough fuel for 16 psi (without the WI) but my IC (BLITZ SMIC) can only support about 14. I only run 12 cause if I get a bad tank of gas, i'll pop my engine. Now I have no fears running 14 psi on pump gas on the street with the water turned on. the chances of the Water Injection malfunctioning and having a bad tank of gas at the same time are slim to none.
9) octain of the gas is increased, due to the cooling effect of the water/alcohol or just water being injected.
10) I wanted a 10th advantage but I cant think of one right now.
Disadvantages:
1) hydrolock. If its set up wrong you could have water going into the engine at idle or when the car is off, killing the engine. not an issue when done right.
2) gas mileage. I would guess that since the timing will be advanced you use more fuel, but thats just a guess.
3) problems are difficult to diagnose. Had some issues early on and took me 3 weeks to figure them out. been running solid for a month no problems daily driving.
4) you have to maintain the water tank.
http://www.rx7club.com/forum/showthread.ph...water+injection
IN a nutshell, I find that my air temps are from 20-32C on a hot day with the WI and it pulls hard as hell even when its 100F outside. I have one nozzle in my elbow pointing 90 degrees down the pipe (toward the hot air) and one in my intercooler end tank. they come on at 8 psi. I have a 2 gallon water tank that lasts a long time. Cost for a single stage setup is about $140, a dual stage like mine runs about $180 for the parts.
Injector and selenoid 1
A view of both the injectors, the other is in the endtank of the IC, you cant see but the other selenoid is mounted behind the IC:
pic of the water tank and the pump:
considering it does the following:
1) steam cleans your engine, sparkplugs and exhaust eliminating carbon deposits.
2) gives sub ambient air temps, therefore advancing your timing.
3) allows you to run more boost than you could without or gives you a huge safety cushion with your current set up
4) car no longer feels like a dog on a hot day.
5) no more heatsoaking or power loss between 1/4 mile or dyno runs. Ok, to clarify you are sitting in traffic for long time in hot weather...your intake sensor will get heat soaked, but as soon as your boost the air will be cooled before it enters the combustion chamber which means that while heatsoak technically exists, it is not relevant because the air is cooled before reaching the engine.
6) my car doesn't backfire like it used to in hot weather. when my intake temps get hot my car back fires upon deceleration, no more.
7) I Could run 87 octain and/or remove my IC and run only water injection.
8) in my case, my car is set up to have enough fuel for 16 psi (without the WI) but my IC (BLITZ SMIC) can only support about 14. I only run 12 cause if I get a bad tank of gas, i'll pop my engine. Now I have no fears running 14 psi on pump gas on the street with the water turned on. the chances of the Water Injection malfunctioning and having a bad tank of gas at the same time are slim to none.
9) octain of the gas is increased, due to the cooling effect of the water/alcohol or just water being injected.
10) I wanted a 10th advantage but I cant think of one right now.
Disadvantages:
1) hydrolock. If its set up wrong you could have water going into the engine at idle or when the car is off, killing the engine. not an issue when done right.
2) gas mileage. I would guess that since the timing will be advanced you use more fuel, but thats just a guess.
3) problems are difficult to diagnose. Had some issues early on and took me 3 weeks to figure them out. been running solid for a month no problems daily driving.
4) you have to maintain the water tank.
08-28-2003, 12:42 PM
#15
Senior Member
Join Date: Nov 2002
Posts: 3,108
talked some people running water injection, and they said you can run a lower octane fuel. Which i understand why. But they also said you can run a lot leaner mixture.
But aren't we still trying to aim for 14.7 stoich? (or slightly richer)
But aren't we still trying to aim for 14.7 stoich? (or slightly richer)
08-28-2003, 01:07 PM
#16
Senior Member
Join Date: Jan 2003
Location: PA Pittsburgh
Posts: 575
I say water injection is good. But you dont need it inless you want to boost high 15+ psi. I woudlent mind testing it out once i get enough money that i dont care if i blow my engine up. Someone go get dragon he prob has some insite on this.
08-28-2003, 03:40 PM
#17
Senior Member
Thread Starter
Join Date: Jul 2003
Location: in my pants
Posts: 227
the only way this can blow up your engine is if it hydrolocks. BUT, autospeed.com came up with a module that varies the flow of a water injection so that it rises with engine load.
http://www.autospeed.com/A_1539/cms/article.html
actually aquamist products feature everything from simple modules that regulate the amount of water injected by sencing boost preasure to ecu's that you can proggram and map it anyway you like.
http://www.autospeed.com/A_1539/cms/article.html
actually aquamist products feature everything from simple modules that regulate the amount of water injected by sencing boost preasure to ecu's that you can proggram and map it anyway you like.
08-28-2003, 03:42 PM
#18
Senior Member
Join Date: Dec 2002
Location: fredneck MD
Posts: 4,107
the thing is, you dont inject at all times. It wiould still be useful to have a intercooler for thoes times off boost. The air has to pass through the hot turbo even when you are not boosting. Lag isnt going to be increased that much by having an intercooler.
08-28-2003, 04:53 PM
#19
Senior Member
Join Date: Sep 2002
Location: bay area
Posts: 235
to clear things up...someone said you dont need it unless you boost 15 PSI...I blew my engine at 12 PSI on the dyno. Water injection would have saved me 6400 for my rebuild and other stuff I got done.
As far as having a 14:7, mine is 12:1 and i'm happy with that. Tuning for a 14:7 would work, but you better never run out of water or malfunction with the WI.
As far as hydrolock, you will never hydrolock as long as you only spray water when you are boosting and make sure the water is a fine mist (EG you need a high psi pump).
For example I'll give you a quick idea how to figure out the nozzle size. You can go with an expensive aquamist that varies the output based on the fuel, but remember its $$$$ to install and very expensive to buy (but worth if if you have the cash) or you can do this..
My nozzle is .77 @ 60 PSI and the other is 3.87 @ 60, so im around 4.65 Gallons per hour. My fuel at 100 pct duty cycle is 3500 CC ( 2 X 1200 and 2 X 850=3500). Here is the chart that gives my totals, the duty is the duty cycle on the power FC, the pct is the percent of water to fuel. you want to be between 10 and 20 pct. As you can see, I never have too much water. I plan to get a 100 psi switch for my pump, that will raise my nozzles to a total of 6 GPH and put me in an even better water distribution. Just don't put too large of a nozzle or your car will drown out and the ignition will break up.
duty pct duty pct
42 19.73% 69 12.01%
47 17.63% 72 11.51%
49 16.91% 75 11.05%
51 16.25% 78 10.62%
54 15.34% 81 10.23%
57 14.54% 85 9.75%
62 13.36% 87 9.52%
65 12.75% 90 9.21%
As far as having a 14:7, mine is 12:1 and i'm happy with that. Tuning for a 14:7 would work, but you better never run out of water or malfunction with the WI.
As far as hydrolock, you will never hydrolock as long as you only spray water when you are boosting and make sure the water is a fine mist (EG you need a high psi pump).
For example I'll give you a quick idea how to figure out the nozzle size. You can go with an expensive aquamist that varies the output based on the fuel, but remember its $$$$ to install and very expensive to buy (but worth if if you have the cash) or you can do this..
My nozzle is .77 @ 60 PSI and the other is 3.87 @ 60, so im around 4.65 Gallons per hour. My fuel at 100 pct duty cycle is 3500 CC ( 2 X 1200 and 2 X 850=3500). Here is the chart that gives my totals, the duty is the duty cycle on the power FC, the pct is the percent of water to fuel. you want to be between 10 and 20 pct. As you can see, I never have too much water. I plan to get a 100 psi switch for my pump, that will raise my nozzles to a total of 6 GPH and put me in an even better water distribution. Just don't put too large of a nozzle or your car will drown out and the ignition will break up.
duty pct duty pct
42 19.73% 69 12.01%
47 17.63% 72 11.51%
49 16.91% 75 11.05%
51 16.25% 78 10.62%
54 15.34% 81 10.23%
57 14.54% 85 9.75%
62 13.36% 87 9.52%
65 12.75% 90 9.21%
08-28-2003, 07:32 PM
#20
Senior Member
Thread Starter
Join Date: Jul 2003
Location: in my pants
Posts: 227
the thing is, you dont inject at all times. It wiould still be useful to have a intercooler for thoes times off boost. The air has to pass through the hot turbo even when you are not boosting. Lag isnt going to be increased that much by having an intercooler.
yeah thats a good point. I though taking out the ic would cut alot onthe lag, but if not then yeah, its definetly worth keeping.
As far as running out of water, unlese you are running something like 30psi and spraying in insane amounts then you shouldnt worry. I knwo people who run at 20+ psi and a 2 gallon tank lasts them 3 gas tanks. And with about between 10 and 17 mpg. At this point water is nto a big problem. You run out of gas alot sooner, and water unlike gas can be obtained at little cost, we are talking cents to no cost.