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Discussion Starter #1
Would like some help here, please: I've looked at what is commercially available and it doesn't make a lot of sense. Lets take my example as a starting point. I have a turbo Harley Vrod. I want to use W/M pre turbo to cool the incoming charge. The units I see use a fixed jet and a huge high pressure agricultural pump to try to vaporize the mixture, combined with a controller that may be boost referenced. I can see this if this is a package strictly dictated by economics, but it seems very rudimentary. Why isn't a regular fuel injector used ( they come in infinite sizes, atomize well and can be easily volume controlled by readily available microprocessors )? A small automotive inline pump could supply the needed pressure ( 40-60 psi, as this is pre turbo it would not need to be pressure referenced). It seems a signal from the MAP sensor could be used to determine increased flow to the injector. What have I missed or where am I off base ? Suggestions/ ideas ? Thanks
 

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The large agricultural pumps are pretty much impossible to match. There are no moving parts in the fluid and no metal parts are wetted. Now if you try to run a fuel pump on water you will quickly realize they seize right up due to no lubrication and corrosion. You might think that water is not corrosive and easy on parts and that line of thinking would be very wrong. Same with injectors, stainless steel internals will still rust and corrode with water.
If you want simple and easy when spraying into the turbo, you just pressurize a tank with boost pressure and spray it into the turbo intake. Works great and the turbo does all the atomization. You will also corrode the compressor wheel leading edge spraying water through it.
 

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You won't wear the compressor impeller if you atomise the water/meth before you spray it in-ie,a proper water/meth nozzle or jet.
 

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You would think that but that is not the case. Spraying a stream of liquid into the compressor doesn't seem to erode the blades. However spraying a fine mist does erode the blades. I have run both on the dyno and this was my results strangely enough.
 

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At my workplace, we have essential two really big turbos....called recompressors. They recompress steam into usable condensate. Each has an impeller about 7' across and the housings are at least 12' tall.
Obviously we would not want particles going through. And steam is fine. But water droplets cause erosion very quickly. And that gets expensive.
 

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Our experience has been different, a few of our cars use water/meth for charge cooling (AIS systems) -all spraying into the compressor mouth- one BBC /Precision combo together for 7 years without any obvious erosion of the impeller, my own combo for two years ,no erosion.
 

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Our experience has been different, a few of our cars use water/meth for charge cooling (AIS systems) -all spraying into the compressor mouth- one BBC /Precision combo together for 7 years without any obvious erosion of the impeller, my own combo for two years ,no erosion.
How many gallons of water have you sprayed through it?
 

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Discussion Starter #8
comments; a) I'm not sure a system using only boost pressure would be sufficient to atomize the mixture or would be able to be easily turned on/off. Were only talking maybe 15-16 pounds maximum on a Garrett T25 b) this is a system that would be demand based, probably come in at 8 pounds & up. A year of riding might use a couple quarts
 

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vw chuck, I couldn't say for sure, around 1 1/2- 2 litres used per meeting, average 15 meetings per year for about 7 years on the BBC combo.
A small electric pump (windshield/headight washer) could be used with a small atomiser jet, turn it on and off via an adjustable boost pressure switch ,if you want it simple.
 

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Spraying a proper fine atomised spray into the impeller will cause it no harm whatsoever. Certainly not during any realistic lifespan of any engine anyone would be using here.

but a low pressure system will need suitable nozzles. The stuff currently available for a pumped system....is clearly not suitable for that application. But there are a lot of hydroponic type systems out there for the likes of a greenhouse or similar that use low pressure spray nozzles, or those similar to squirty bottles for various cleaning type compounds ( although obviously they're not suitable )

The thread over on the Aquamist forum about pre compressor injection has already covered almost any configuration anyone would want to try
 

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Musi used to sell a pump less water injection system. You could use nitrous or CO2 to pressurize the water.
Not sure if still make it.

We use water injection in diesels a lot. But we use engine driven pumps. The electric systems can make the pressure needed to inject water properly at the boost diesels often run.
 

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Rodney at Pro Meth makes the pumpless system that uses co2 for pressure.
Yeah Pro Meth Immediately came to mind. They also have a volute injection system.

I don't think you can get away from damaging the compressor by spraying at it; liquids are a lot more dense than gases. Turbos weren't designed to compress liquids, nor to phase change liquids into gases. That said, spraying pre-compressor etc effectively extends the compressor's efficiency. So there are gains to be had from it. All comes down to your willingness to replace the parts as necessary.
 

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Good thread on spraying pre compressor.
 

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The fact that you're on a motorbike...a co2 based system probably makes a lot of sense.

You may already be using co2 for boost control ? maybe an air shifter ? so why not also use it for water injection ?

It adds no weight, it offers plenty of pressure to work with so you can spray it wherever you want using readily available nozzles.
 

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Nothing compresses liquids.......period.
 

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This is what I was responding to. I guess I should have quoted. Was just being a bit of a smartass pointing out that nothing can compress a liquid.


Yeah Pro Meth Immediately came to mind. They also have a volute injection system.

I don't think you can get away from damaging the compressor by spraying at it; liquids are a lot more dense than gases. Turbos weren't designed to compress liquids, nor to phase change liquids into gases. That said, spraying pre-compressor etc effectively extends the compressor's efficiency. So there are gains to be had from it. All comes down to your willingness to replace the parts as necessary.
 

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This is what I was responding to. I guess I should have quoted. Was just being a bit of a smartass pointing out that nothing can compress a liquid.
Yeah technically you can compress water and some other things, to varying degrees. But that's not what a turbo can do. So you're just slapping little droplets at crazy high speeds when you spray pre compressor.

It might have some gains, but if you have a nice turbo you want to keep, not the greatest idea. If it's a chinese turbo or you just want to send it, go ahead.

If you are set on it, I know people have better long term success spraying with pure meth pre compressor.

You can do the same thing just down stream, with no real draw back.
 
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