Single Turbo RX-7's Questions about all aspects of single turbo setups.

Water Injection

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Old 11-14-01, 12:54 AM
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Question Water Injection

Has any one had any experience with water injection on their turbo rotary? I have done as much homework as I can find on the subject and all seems to be pretty good. The drawbacks being that you have to continously replenish the tank doesn't bother me. Let's hear it......
Old 11-15-01, 07:55 PM
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I also want to know more about this topic....
Bump.........
Old 11-16-01, 02:24 AM
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This is a very touchy subject. Some people swear by it, others think that it is a substitute for adequet tuning / fuel / octane.

Water acts to cool the intake charge and combustion camber. Reducing the engine's tendency to preignite... knock.

I use it on my turbocharged Z3... since it only uses a RRFPR and I have to run 89 octane fuel... it lets me run an extra 4-5 psi without knocking.
I do not use it in my FD since it is fully tuned with a Haltech E6K and I only run 15 psi.
Old 11-16-01, 08:23 AM
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Guys, in case you didn't notice, this is a technical forum. Keep it on topic or don't post at all - period. I deleted the off-topic BS posts.
Old 11-16-01, 08:34 AM
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what the heck. My post about Corky Bell says NO! was on topic
he is very opposed to water injection. Says so in the book im reading right now. I thought that might be something since he is pretty good w/ turbos
Old 11-16-01, 12:58 PM
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There are huge benifits to be gained by running water /mathanol injection. You can run more advance without pinging, you can run more boost on pump gas, so you can overall make more HP. anyone who says that it doesn't work, has got their head cross threaded.


Well done Ryan...........
Old 11-16-01, 02:54 PM
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Originally posted by Node
what the heck. My post about Corky Bell says NO! was on topic
he is very opposed to water injection. Says so in the book im reading right now. I thought that might be something since he is pretty good w/ turbos
I would like to see Corky Bell tell that to the F1 engineers during the turbo era. I'm not bashing on what you're sayin, its just that Corky Bell isn't always right. Water Injection adds a nice buffer zone that can save your motor sometimes.
Old 11-16-01, 03:27 PM
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Lightbulb

Well the history on water injection goes back to WWII, the P-52 Mustangs we're supercharged and to get enough cross sectional area for an intercooler, would eventually lead to worse aerodynamics.....hence the inception of water injection. To cool things down. Corky Bell has said some strange things. I too have read his book. If you want better overall cooling go with nitrous, but it's more expensive and doesn't benefit from the tuning. Plus it requires more fuel.......Water injection SHOULD net you better gas mileage.
Old 11-16-01, 07:06 PM
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Isn't this how Jim S. is getting to run his boost in the mid 20s. Water is the recipe for having the motors live with the high boost. Cooling the air/fuel charge with water has been around for a long time and works. We setup racing motors way back in 1979 with water injection and a little alcohol to prevent it from freezing (at least that is what they said).

regards

Rick
1993 RX-7
Old 11-16-01, 09:06 PM
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Originally posted by Amir


I would like to see Corky Bell tell that to the F1 engineers during the turbo era. I'm not bashing on what you're sayin, its just that Corky Bell isn't always right. Water Injection adds a nice buffer zone that can save your motor sometimes.
I know
He has a rather strict tuned or **** theory
Old 11-17-01, 12:54 AM
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Originally posted by Node

I know
He has a rather strict tuned or **** theory
Mr Bells theory regarding water injection can be placed in the... "I know **** department"

There are many advantages to running it, I have used it for years on my own cars and on customer cars with alot of benifits.

Do a search on the topic, as it has been talked about before at length. It does work, and it is not a patch up as some idiots would have you believe.
Old 11-17-01, 02:59 AM
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my basic concern is this. the stock intercoolers are really crap, both 2nd and 3rd gens. However, with the benefit of running water injection, you could lower the intake charge temp significantly. The cost for a system from spearco or Aquamist is less than $300 dollars. No way a good intercooler kit would cost nearly as much. that's pretty much the way a lot of the Grand national guys do it. Eventually when you do get a better I/C. You would reap both benefits.

I would like to know how much water is needed to be run....i.e what size jets and how much further would the timing need to be set. I think i pretty much have made up my mind.

Nitrous Express claims that once you have Water Injection set, it's much easier to tune Nitrous.
Old 11-17-01, 04:31 AM
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300cc per minute when above 10psi boost above 5000rpm, below those parameters you need a lesser percentage, anything under 7-8psi below 4000rpm doesn't really need it
Old 11-17-01, 05:36 AM
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yeah, corky isnt godlike but his book definately helps out on alot of stuff although there is a lot of **** that could be changed/slightly modified/taken out or added
Old 11-17-01, 05:35 PM
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HWO:
Did you have to add more fuel when you added the water? I'm running 10 psi at about 4g and would like to have the torque stay a little flatter. Who's system are you using and did you like it? I probably won't run as much water first, but then would increase it slowly. Thanks for all the info......keep it coming.
Old 11-17-01, 10:12 PM
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i'm have a very homebuilt system which i chucked together with whatever **** i could find lying around, i am currently not using it, but it does work. basically works on a pressure switch, windscreen washer motor and a irrigation spray nozzle
Old 11-17-01, 10:50 PM
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Water injection

I also thought about water injection and its advantages. Has anyone tried injecting water or a water-alcohol mixture using alcohol injectors?
Old 11-18-01, 02:47 AM
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Wow that's serious bussiness, i don't think you would nee that much water...the average aftermarket system uses, much smaller jets .
Old 11-18-01, 03:31 AM
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Originally posted by fastrotaries
Wow that's serious bussiness, i don't think you would nee that much water...the average aftermarket system uses, much smaller jets .
300cc per minute is what Peter (RICE Racing) reccomended, who plays with water injection on this forum more than him?????
Old 11-18-01, 09:34 AM
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Theory question

Would it be better to inject the water after the turbo, so that it is injected into the hot, compressed air, or just before the turbo, so that it might get more atomized by the compressor?

I'm thinking before might be better, because you wouldn't have to worry about good atomization from your nozzle, but I've read on numerous occasions that after is better. Hmm.

I don't think I'd run such a system without safeguards, like a boost cut when the tank runs low, but the idea is... fascinating.
Old 11-18-01, 10:42 AM
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Pre turbo?

Would pre turbo injection cause erosion to the compressor blades? I know they are spinning kinda fast. I would think you might have problems puddling too... if you run too much. Other than that I think it might be a good idea.
Don.
Old 11-18-01, 06:43 PM
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I know that injection in front of the turbo is how a lot of racers do it, but then again they don't even run an air filter......i'd say right after the turbo.......but most of the pictures i've seen on 2nd gen that have W/I do it right before the TB.....Same goes for nitrous.
Old 12-08-01, 10:42 AM
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Water injected before the intercooler will condensate. Systems without IC can spray direct in the Turbo inlet, with IC it won't work well.
Old 12-08-01, 04:59 PM
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Originally posted by SpiceMike
Water injected before the intercooler will condensate. Systems without IC can spray direct in the Turbo inlet, with IC it won't work well.
Most people i know running water injection spray it pre turbo and then it flows thru the intercooler, dont know of any of them having problems with condensation.
Old 12-08-01, 05:04 PM
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Cool

Let the intercooler do its job then have the wter injection after the intercooler. Seems this would offer a cooler charge prior to combustion.


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