Fuel Injectors as Water/Meth Injectors
 

Hi,

I'm looking to design a water injection kit using a high pressure fuel pump, some top feed fuel injectors with an rx7 lower fuel rail. My only question is how much flow do i need. I see some people using nozzles rated at 6 - 8 lbs per min for their injection systems. But about the smallest injectors i have lying around are 19 lbs. Will this be too much? If so I will need a way to adjust injector duty cycle...which i think is very doable.

BTW I am building this system for a turbocharged 4g63 2.0 liter running 20-23psi of boost on pump gas and would like to run 50/50 water meth.

TIA!

I had the very same idea, and I don't think it would be a problem if you had a method to control the injection. My plan was to use the staged injector setup of Megasquirt to control it as extra fuel. With the ability to control injector duty cycles, there shouldn't be a problem with injector sizing as long as it's reasonable.

The problem, however, with using them for a meth system is corrosion. As far as I know, the whole system that you use for the meth injection has to be designed for alcohol (ie, you can't just use normal injectors, you'd have to get injectors designed for alcohol). Otherwise you'd probably encounter problems with corrosion.

Re: Fuel Injectors as Water/Meth Injectors
 

RB Racing tried it years ago and found lots of corrosion, very quickly.

What makes you think that fuel pumps or injectors are happy pushing water? :?:

Re: Fuel Injectors as Water/Meth Injectors
 

eh just a friends crazy idea

so i should stick to fuel oil burner injectors? lol - what i'm confused with is how large to size them

2.0 turbo ~300-350 crank hp

You can buy corrosion inhibitor for radiators cheaply. I'm planning on trying a similar setup with a little corrosion inhibitor added to the water. The parts I need for my prototype should arrive by the end of the week.

If it works, it will be a nice, cheap system with full mapping capability.

well i gave up and bought a solenoid and a 6.3gpm mister nozzle from mcmastercarr last night :lol:

Interesting! I totally hadn't thought about that.

One thing to keep in mind is that the specific gravity of fuel is less than that of water. So a an amount injected at certain flow rate at a certain pressure for fuel will be less than the amount injected if the fluid is water.

Measuring the delivery rate is easy - just have it squirting for a minute in a calibrated container.

It would be interesting to see if corrosion inhibitors do help a fuel pump and injectors push water. Hadn't thought of that :eek:

Got the control curcuit built up last night, the FPR should arrive this afternoon, hopefully, I'll have it in prototype state by next weekend..

Here is the build of the control curcuit, it all came from a local electronics shop in kit form www.jaycar.com.au

I'm using a Pulse Width Adjuster to control the duty cycle of my injectors.

Here is the initial board build up:

http://img122.imageshack.us/img122/6596/wi16hy.th.jpg

I've also built a duty cycle counter/generator just to make it easier to bench test it all.

For a quick demo of the adjustability, I took these two pics:

In this one, the engine is at 41% duty (LED display), and the adjustment for this duty cycle range is set to +16 units, which results in an injector duty cycle of 54.8% (multimeter).

http://img212.imageshack.us/img212/6520/wi28pl.th.jpg

By changing the settings on the adjuster to -28 units, I've altered the output of the device to 20.2%.

http://img133.imageshack.us/img133/9414/wi30su.th.jpg

This give me a lot more adjustability than I really need, and it's fairly cheap and simple (but, you have to build it yourself)....

I could probably use a megasquirt for the same functionality, but, I really like the way this is indexed to the fuel injector duty cycle, this way I just need to work out the percentages, then whatever tuning changes are made to the engine, the water follows.

Still tossing up weather to use corrosion inhibiter or soluble oil to protect the injectors.

I fired up a prototype setup using corrosion inhibiter last night, the sickly sweet smell when it fired up was 'interesting', but, it seemed to work.

I kinda like the toxic green colour though.

The spray adjustments via the duty cycle worked perfectly, I was able to get from a soft, barely wetting spray, all the way up to a remarkably high flow, but, just turning a trim pot.

http://img230.imageshack.us/img230/8...stem0fd.th.jpg

The spray pattern is kinda horrible, but, the injector is old and I have no idea when the last time it was used, so I'm hoping the pattern will improve after a clean.

This is the only picture where you can see the spray.

http://img126.imageshack.us/img126/2940/spray6xz.th.jpg

It seems to be very concentrated and jet like, rather than a mist, I think I've seen pics of blocked injectors with a spray like this so I'm hoping that's all it is.

interesting... any updates?

I've tried some other injectors which seem to spray a nicer, finer mist, but, I've been distracted by other projects.

Hopefully, I should be able to get back to it in a couple of weeks or so...

Check out http://ausrotary.dntinternet.com/for...water+soluable

This is the same idea I have been discussing with a few other guys. Seams soluable oil at a rate of 10-15% in water works fine. Has a good artical about BWM doing the same thing in the eighties

nice!

thanks for the link.

-ken

For even more reliability you should use the Lucas disk type all stainless injectors. The internals of these injectors are 100% Stainless.

I have been in the lubricants business for about 12 years and I want to put out the thought that certain additives may help prevent rust or corrosion but may cause deposits to form if they do not burn cleanly.All chemicals,even motor oil when burned leave some residue.In a motor oil this is called sulfated ash content,measured by percent of weight left over after the oil is burned.most motor oils have an ash content of about 1%.Think of it like a cigarette burning and the ash thats left over.I just want you to consider that some chemicals you add to you WI mix may not burn off that well.More specifically,its not so much the oil itself that doesnt burn cleanly,but the additives such as antifoam,rust&oxidation inhibitors,detergents etc.that leave the deposits.The discussion of adding chemicals to WI just caught my eye is all.I would hate to see you guys use an additive that created harmful deposits.---

Maybe the WI would keep everything clean enough so that deposits are not a factor so maybe,on second thought there isnt that much cause for concern.As far as soluble oils go though they can get a fungus cake at the bottom of the tank wich may clog small orifices.I have been playing with the idea of adding a high quality synthetic two cycle oil to the water/meth mixin the neighborhood of 100:1.what do you guys think?

Would the deposits remain the in the chamber though.

I'd assume they would be evacuated by the exhaust, in a car without a cat converter they should get blown straight out the back. The other question is, would a cat converter break down the residual deposits?

Ben Did you ever get to try the newer FULL stainless internals? Has that "toxic green stuff" solved the problem of corrosion? Also were you test ingecting h2o/meth/toxic green stuf or just h2o /toxic green stuff? I have a very similar home made controller that is based off of rpm and boost, (1 bar right now, still string to solve that problem I need at least 2 bar) it has similar controls to the dash pot, 1 for base rate and 1 for gain.

I was curious about wether anybody made an injector you KNOW could survive water/methanol. I have never disassembeled an injector but my buddy was telling me they have windings submerged in the fuel and that he thought the meth would attack the dissimilar metal windings. Curious if anybody has any more info on this?

Hi all, well Meth is supposed to be aggressive to rubber parts... I think to have discovered it by using aquamist systems... :lol: but it is not supposed onto metal components. That should be really too much aggressive...

Rubber is pretty generic I have found many materials that have good compatability.

Here is a small list of "rubber like" materials

O-Ring Materials Compatible with Methanol

Aflas (0) Buna-N (Nitrile) (3) Butyl (1)
Chemraz (4) Epichlorohydrin (0) Ethylene-Propylene (4)
Fluorocarbon (0) Fluorosilicone (4) Hypalon (4)
Kalrez (4) Natural Rubber (4) Neoprene (4)
Nitrile, Hydrogenated (4) Polyacrylate (3) Polysulfide (0)
Polyurethane, Cast (0) Polyurethane, Millable (2) Silicone (4)
Styrene Butadiene (0) Teflon, Virgin (4) Vamac (4)