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Discussion Starter #21
So then would the best option be to do a volute spray, mix of H2O & meth, using CO2 to pressurize the mix ( bike application) ? Second question; If you're carrying say, a one quart mix supply, where do you apply the CO2 to pressurize ? As the storage volume goes down, you need ever increasing amounts of CO2 to run the system.
 

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Fill a small bottle, much like a small fire extinguisher etc, or just another co2 bottle so to speak.

Obviously the air supply to this would need regulated down to a more sensible pressure, maybe 150psi or so. Which would be more than adequate for good atomisation for a pre-compressor setup

Given the tiny volume of air/co2 you would be moving it would be negligible compared to what is stored in the high pressure bottle. Much the same as boost control using co2, which is also a total loss setup
Or an air shifter, etc etc.

You'd never use say a full litre or quart of fluid during a 1/4 mile race....so you'd only need a max of a litre or quart of air. Which is nothing really.
 

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Discussion Starter #23
Steve, so I have a source of mix at atmospheric pressure. I reach my boost point, say 8 lbs, a switch turns on the CO2 bottle ( regulated down to 150 psi, I get a jolt of pressure to the mix.... it's now going to keep flowing until I vent out the bottle back to ambient air pressure ? Wouldn't that blow out the whole quart ? How do I control the presure / timing /flow to keep it restricted to time under boost & then cut it off?
 

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Yep. not that much consumption. Is there any reason not to use straight meth? I'm just thinking it may atomize even better with the low heat of evaporation. The only downside I see straight off is that a backfire will light in the pipes at that point.
Oh, Biondo has fairly small co2 bottles. You may find ones cheaper or different sizes that may work better for you. Make sure the meth bottle will take the pressure of the co2. We can be talking over 1000 psi unregulated. You don't want that coming apart between your legs.
 

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Steve, so I have a source of mix at atmospheric pressure. I reach my boost point, say 8 lbs, a switch turns on the CO2 bottle ( regulated down to 150 psi, I get a jolt of pressure to the mix.... it's now going to keep flowing until I vent out the bottle back to ambient air pressure ? Wouldn't that blow out the whole quart ? How do I control the presure / timing /flow to keep it restricted to time under boost & then cut it off?
If you are using a solenoid to turn on the pressure, have it turn off under 8 psi or something like that. I would be tempted to keep the regulated co2 in that charge bottle at all times, and just use the solenoid at the output from that bottle. Otherwise engine vacuum at idle could pull out of the bottle/
 

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Steve, so I have a source of mix at atmospheric pressure. I reach my boost point, say 8 lbs, a switch turns on the CO2 bottle ( regulated down to 150 psi, I get a jolt of pressure to the mix.... it's now going to keep flowing until I vent out the bottle back to ambient air pressure ? Wouldn't that blow out the whole quart ? How do I control the presure / timing /flow to keep it restricted to time under boost & then cut it off?
Use a solenoid.

I'd keep the bottle pressurised, then use a solenoid prior to the nozzle and open it when needed. Yes it is a basic setup though.

Or if you used boost pressure to fill the reservoir and push the fluid out, that can work too with suitable atomising nozzles that work at low pressures as already said.
And are covered in the Aquamist forum thread I mentioned.

 

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Been doing for almost 10 years on my rotary powered RX7, same engine, was my DD car when not on the motorcycle up to about a year ago. I just replaced the turbo due to needing a rebuild, ended up ditching the old school garrett T04S for a SXe 62mm, bearings were shot, and there was no noticeable errosion on the compressor wheel.

Keep it stupid simple...

1 - Make your water/Alky tank out of thick aluminum
2 - Run a line from your Turbo to the top of your aluminum water/alky tank
3 - Run a line from the bottom of the tank to a solenoid
4 - Run a line from the solenoid to your pre turbo nozzle
5 - Use a nozzle similar to this: Internal Mix Wide Angle Round Pattern Atomizing Nozzle and plumb it as required (line from item #2 also needs to be run to the nozzle)

Thats it, all mechanical, except for the solenoid.

Now, I dont deserve the credit, google rice racing pre turbo water injection, he was the first person I ever heard talk about pre turbo water injection, somewhere back in the mid 90s. Not that he invented it, but he did a lot of testing on his own, and share lots of information (back then). Here's a video of his system that he posted back then:

 

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So, my question becomes: Why pre turbo?
I may have the wrong logic on this. But why would you want to sent more mass through the turbo that isn't air? And why would you want to heat up that methanol as you go through the turbo? The delta T possible after the turbo is much greater than before. What is the thinking on going pre turbo for injecting a cooling liquid?
 

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Yea spraying through the turbo doesn't really decrease the heat of compression. The most bang for the buck is to find the highest air temp in the system and spray at that point.
 

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Any questions asked, have already been covered in the Aquamist forum thread.
I'm not sure entirely what to make of some of the posts there and elsewhere on the subject. I even saw people posting that if the fluid is not completely atomized, the wheel will take care of it! I'm not sure I want that to ever happen. A few said that it can slow the acceleration of the turbo. More than a few said that it increases the efficiency of the compressor due to filling in the clearance between the blade tip and the housing. But if it is completely atomized, I'm not sure that argument holds any "water". I guess the one scientific theory was that the compression happens more closely to adiabatic. Well.....Thermodynamics was a long, long time ago for me. So I can't speak to that.
I guess it all comes down to reliable experience speaking to it.
 

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Why pre-turbo? Spraying water/meth into the compressor cools the compressor impeller and the compressor housing. The next 'gulp' of air that goes into the compressor now hits a cooler impeller and housing, hence the air is denser, hence more mass air can be packed into the same space, and more power results from this. Plus the evaporative process of the water/meth travelling through the charge tubing cools the tubing etc.
Many years ago when I first started playing with turbos, I used some of the stick on temperature strips on the compressor housing , there was a significant temperature reduction with pre turbo water/meth injection compared to no pre turbo injection.. This convinced me that it was worth doing. I'm sure there are other benefits, but this I believe is the main one.
 

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The heat during the compression process doesn't come from the heat of the actual metal parts it comes from the heat of compressing the air. Try putting an air temp sensor in the airflow right at the outlet of compressor housing and run a pressure ratio of 3 or so for a few minutes on a dyno. You will see 350+F degree temps. Now spray into the inlet of the turbo and you will see 325F or so on the outlet. Not a real big decrease in temp. I learned many years ago that you want to put your chemical intercooler at the point of highest temp. In this case you want to spray it at the 350F air coming out of the compressor housing not at ambient air entering the compressor. This is real data that I collected on a dyno many years ago. It isn't heresay from a forum of talking parrots repeating each other.
 

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vw, did you do any temp measurements downstream of the compressor (if so, how far down?) when spraying the same amount pre and post turbo?
 

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Yes, we all know that compressing the air causes it to heat up, but heat also travels to the compressor impeller and housing through the turbine shaft and centre section. (put your hand on a compressor housing after a 1/4 mile run, engine is off, no charge compression is taking place but the housing is f*cking hot! And gets hotter for a short period as heat transfers). Never mind how or why the compressor impeller and housing gets hot - spraying a cooler atomised liquid into the compressor mouth does cool the metal parts, and incoming air then contacts cooler metal surfaces than if no water/meth injection was used. Not hearsay, not parrot fashion, just simple physics.
 

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I personally spray into the compressor mouths and just before the throttle bodies. Best of both worlds IMO.
 

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FYI, real world measured results.... Before WI 360f. After 170f. 1 x 1.2mm nozzle per turbo. Just water with turbo pressure on top of the water in a 1 litre bottle. Uses .8ltrs per pass. Wheels are anodised for better wear. Nozzle at 60psi in the video. You're welcome...
Water injection nozzle video.
 
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