Home made water injection

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Frederick Stienheld
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Post by Frederick Stienheld »

The water is being injected just after the turbo output, so it is in the main air stream and will be going to all cylinders. As such you may as well just trigger it in relation to 1 cylinder pulse (hence RPM) & the current boost level, if you know what I mean?

As he has said, it will be triggered at 5 or 6 psi... what he needs to do is have the duty cycle increased with increased boost pressure rather than having the fuel pressure increased with boost pressure. And the fuel pressure should sit at a constant pressure to suit the injector being used.

That's my thoughts anyway.
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kheading
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Post by kheading »

Frederick Stienheld wrote:The water is being injected just after the turbo output, so it is in the main air stream and will be going to all cylinders. As such you may as well just trigger it in relation to 1 cylinder pulse (hence RPM) & the current boost level, if you know what I mean?

As he has said, it will be triggered at 5 or 6 psi... what he needs to do is have the duty cycle increased with increased boost pressure rather than having the fuel pressure increased with boost pressure. And the fuel pressure should sit at a constant pressure to suit the injector being used.

That's my thoughts anyway.
I understand what your saying here.
Yes in a factory injection system, when the motor needs more fuel, the computer pulses more or longer to increase the rate of fuel delivery but on a budget aplication, you can trick the injectors to deliver more fuel by increasing the fuel pressure behind it and still run at the same pulse.

I hope i can borrow this idea to work in my system as i think/assume that the jaycar injector pulser will only offer one pulse rate once set.
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Post by Burntrubber »

Just my 10 cents about a year ago me and my mate made a water injection system for his turboed Ford Laser. We used a washer bottle pump from a VT Commodore because they run about 35-40 psi rather than 25-30 thats all most jap ones do. We used a proper misting jet from Aquamist cost $30 if I remember right and an adjustable pressure switch to turn it on at 10 psi. Everyone we asked said pfft won't work need better pumps relays solinoids ect ect but it works. The reason he did it was he has no intercooler and he wanted to run 12 psi or higher. It ran reliably for about four months then blew the head gasket the iternals of the engine were clean as. Its still going now he just has to make sure it does'nt run out of water he recons you can tell when it runs out. To get around it running out he could get a late model washer bottle with a low level indicator I seen a VW with one.
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Post by DR_GEM »

Thats an awesome idea burntrubber - i was actually thinking of using an auxilary output on my aftermarket ecu to control the timing of such a water injection setup but was gonna use a hobbs pressure switch with a water fountain pump - although i think the water fountain pump maxes out at like 7 or 8 psi so i dunno.

Just another question occurred to me, if say for instance the spray was constant ie all the time, will this have the ability to fry your rods you think even at low rpm and low air speeds\boost?? cos maybe as a mist being sprayed at say a constant 10psi, would it be strong enough to cancel out the minimal fuel spray from injectors at low boost\rpm or even idle? or is the problem with running it constantly merely one of longevity of the parts\water supply involved? anyone?
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Post by Gemi Coupe »

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Post by Crumz »

Gemi Coupe wrote:You could set the water lines up so it circulates back to the tank, which would help to keep it cool in the lines, by running from the pump, to the injector rail(and injector) and throught the presure reg, then back to the tank.
Thats a damn good idea.
you could use a micro switch on the throttle, so that at (example) 1/4 throttle the water pump begins circulating, with enough time to prime before its needed.
I was thinking the same, except in a little different way, but then I thought what about overtaking? Going from a low throttle/no boost situation to a full throttle/down a gear/high boost situation only takes a millisecond, but it'd still take at least a second to prime the lines (I would think).
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Post by GEM184 »

Turbosmart Eboost2 has a aux output that can be used to switch water injection on at desired boost or rpm. Plus you will have a great boost controller as a bonus just a thought...
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Post by Burntrubber »

I looked at doing water injection for my TG instead of an intercooler I was going to make it better than my mates one. I lined up these cheapish 12v pumps from cdax systems they are alot cheaper than Erl or Holly those were the only other available that I could find. I scraped the idea because I got a intercooler for $20.

Heres a link to those cdax pumps

http://www.c-dax.co.nz/efx/include/comm ... U&CatID=22
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Post by FieldEffect »

:? if you were in melbourne i could knock you up a simple circuit with a microcontroller to control your water injector.

You can build up a table of rpm, MAP, TPS any input you want and output a dutycycle to the injector

I have a mate at the moment building a circuit for an STI performance workshop in melbourne that controlls front mount intercooler water sprays for WRX's based on MAP and TPS.
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Post by kheading »

Well ive learnt that the earlie vl pump used a steel impeler with an alloy casing, while the later model used a plastic impeler so i should a fair bit of life out of it. The stainless steel water tank is made with inbuilt surge thank in it and vl pump mounted on it. Ive learnt that i can increase the base pressure of the malpassi regulator to around 60-70psi witch will atomise the water well enough. The plan is to (hopefully) tune the motor to run on 15psi with out water, incase the system fails for any reason, then the water will be introduced as a cooling bonus.
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Post by isuzu_gem »

i have help design a system on 10sec-rx7 car that we used at summernats. it was the highest hp 13b on pump fuel ever in the event which made 463hp@ the wheels on 18psi with a relativly small turbo for todays standards (t66)
it was a relativly crude set up but worked as long as it was set up properly, we used a high quality irragation mist nozzle which was set at a 90deg angle to the air flow to improve atomisation, the fluid tank was pressurised with boost pressure and when it reached a certant level of boost (in our case 14psi) the computer shiched on a solinoide at over those levels which was inline to the mist nozzle,we found that if we tuned it with out the water injection (we were going to try a water/methonal mix but wasnt alloud) it would loose power with the water injection turned on as the water acts like fuel and takes up space in the inlet charge but inlet temps were down 13deg!, when tuned with the water injection on during the power run it gained about 15hp as it alloud more timing at the same boost levels and the inlet charge was lower than befor. turning the water injection off but using the same tune ended up leaning out and nearly destroying a motor.
after the whole experimant we decided to not do it anymore as in real world situations it wasnt very practable but for summer nats it worked better than we hoped for
i have spent some time thinking about how to improve the set up and have found a good way to get a better atmotisation and so u can use it after the compressor and i would use it with a 50/50 water methonal mix,
early style volvo efi injectors used stainless steel insides and are around 400cc so the methonal wont corrode it and the water wont let it rust up, u can get bilge(spelling) pumps that will be able to suply up to 60psi and have plastic or stainless steel blades that will withstand the mix and are 12v too problem with our old set up and most common types is being able to change the flow rate to suit the motor and u will need something to be able to pulse the injectors and get the flow right for all conditions, with the old set up it was great for top end power but for mid range power it affected the power because the inability to regulate the flow, using something like an old microtech digi computer set up just for the water injection would work well and would be able to be used for other functions of the car like thermo fans ect ect (sorry but i dont know if you already use an aftermarket computer) u can use the aux out put of the digi to tell the main computer(if it is an aftermarket type) to retard timing when the water level is low with a common level switch you can find at the wreckers

unless set up correctly it wont make much of a difference to power
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Post by antus »

Crumz wrote:
Frederick Stienheld wrote: Surely altering the delivery pressure isnt going to alter the flow from the injector? Wouldnt the injector be designed to work over a range of pressures? To accomodate for fuel pump fluctuations? Isn't the duty cycle the only way to control the supply from an electronic fuel injector?
In a basic summary, yes. That is the only way to increase the amount one injector will flow.
However, a larger injector will also flow more than a small injector for the same length of open time (duty cycle).
Are you guys sure of this? I thought the fuel pressure regulator kept the pressure constant despite pump variations because it did alter the flow through the injector. More pressure=faster flow=more fuel for the same open duration. Im pretty sure the injectors have no form of regulation.

If you have a rising rate regulator the pressure vs air delivery/fuel requirements is still constant so the last thing to do is to set your air/fuel maps on the ECU and by doing so your taking the line pressure in to account. As soon as you change something that effects these balances (intake restrictions when using MAP sensor too I figure) then you need a re-tune.
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Post by Buggzy »

there is heaps of info and guys selling complete kits that have been prooven. on AUSROTARY.com
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Maloney2203
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Post by Maloney2203 »

good idea
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Post by jackybee »

street commodores in there tech section have a water injection part check that out
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