Water/meth Injection Kit.

[Daboss]

Hey there forum just a quick question for you, about the topic. I was wondering what the effect of just running distilled water through the injection kit would have? Would it raise the octane level or would it just lower intake temps? Would just using distilled water lower the afr's or would it just lower the intake temp?

[TiTAN]

it suppresses detonation / lowers intake temps a little, the methanol is what raises the octane level, ideally you want to run a ~50/50 mix of the two.

there is no point shoving a WMI kit on there unless you are going to tune the car to make use of it (like running your mothers starlet on leaded race fuel just because you can when really all it needs is 91 ron)

edit: Have a read of this. http://forums.nasioc.com/forums/showthread.php?t=937176

Edited July 6, 2009 by TiTAN

[rtune]

water suppresses detonation, which as avoiding detonation and being able to advance timing

is the objective of a higher octane rating, so water seems just fine to me .. yeah so a mix or

pure meth is more hardcore, but nothing wrong with water.

the trick is getting the atomization right, and getting the quantities right for engine load,

boost pressure, and so on. WMI kits are scary simple: a nozzle like the kind you find in

a greenhouse (or two) and a pump, of the kind you find in a motor home. And a controller.

And a lot of tubing between the nozzle and the pump..

compare that to a fuel injector that can pulse a precise metered quantity of fuel to

the millisecond..

so I reckon no matter what, there will be places where you are misting too much,

or misting too late, or misting too soon. None of this might matter but it getting the

setup working right and then taking advantage of it with a tune is an inexact science..

if you get it right there are amazing gains to be had, similar to the gains if you

got a specific 110 octane race fuel tune. But then remember you are out on a limb

should the injection cease at full boost, you get detonation all of a sudden..

[benro2]

it suppresses detonation / lowers intake temps a little, the methanol is what raises the octane level, ideally you want to run a ~50/50 mix of the two.

edit: Have a read of this. http://forums.nasioc.com/forums/showthread.php?t=937176

In fact, using water alone *will* increase the effective "octane" rating, but not as much as with a 50/50 water/methanol mix. I don't know where that website got its info but they're definitely wrong in saying that *only* methanol will give you an effective raised octane rating! Normally I wouldn't argue with a properly written article on a website, but I've read all the autospeed articles below and they refer to actual tests conducted on actual WW2 planes. Some of the results are pretty astonishing - something like a raise in 20 octane points when using a 0.6 water:fuel ratio (probably a LOT more than you want to run on a car though!)...

To the OP, there are a few good articles on autospeed:

http://autospeed.com.au/A_107970/cms/article.html

http://autospeed.com.au/cms/A_110212/article.html

http://autospeed.com.au/cms/A_110213/article.html

http://autospeed.com.au/cms/A_110368/article.html

http://autospeed.com.au/cms/A_110369/article.html

http://autospeed.com.au/cms/A_1539/article.html

It probably makes sense to use a 50/50 water/methanol mix though, unless you're doing it for fuel consumption (ie: running very lean all the time, meaning water is being used even when off-boost), or you don't want to have to run fireproof lines in your engine bay due to the methanol, etc.

As for your original question: yes, it does raise the effective octane level. You don't *have* to run distilled water - tap water will be fine if you run it through a filter - but distilled is obviously better. Yes, it will definitely lower the intake temps, but it can actually increase the AFR's at the same time.

Have a look over on performanceforums.com - there are a few people on there who are very knowledgeable on the subject!

[TiTAN]

The bit you seem to be missing is that the water doesn't aid in the combustion at all, it is there to cool down the intake/hot spots in the combustion chamber. Simply adding water into your petrol doesn't change the ron rating on the other hand mixing something like methanol/toluene/heptane/acetone which do aid in the combustion into your fuel will effect the ron rating though the heptane probably isn't going to do you any good in an engine.

Edited July 6, 2009 by TiTAN

[Daboss]

Thanks guys responses were excellent and I have loads of information on the subject. What I understand is water is good but with high cooling properties. Just water will cool down the intake temps and at the same time might make fuel mix leaner which will increase afr's, were a 50/50 mix will yeild a greater octane number and definetly lower afr's. So water good but, methanol/water much better.

Edited July 6, 2009 by Daboss

[Daboss]

Hey guys I have a question to ask bout my kit. I am now running 50/50 methanol water mix and upon injection into the system I do not see a drop in afr's. Isn't that what the methanol suppose to do richen up the mixture?

[r33_racer]

Try increasing the jet size.

Also should add 1% oil into the mix for lube

Edited July 7, 2009 by r33_racer

[**RB2530**]

The bit you seem to be missing is that the water doesn't aid in the combustion at all, it is there to cool down the intake/hot spots in the combustion chamber. Simply adding water into your petrol doesn't change the ron rating on the other hand mixing something like methanol/toluene/heptane/acetone which do aid in the combustion into your fuel will effect the ron rating though the heptane probably isn't going to do you any good in an engine.

Just want to clear this up...

1. Water technically doesn't burn and aid in the combustion but there is a theory that the water 'may' dissociates producing Oxygen and Hydrogen which will aid in the combustion.

2. RON or Research Octane Number is a 'relative' number that decribes how the fuel behaves (with respect to pre-ignition) in comparison to reference fuels that are made up of different ratios of iso-octane and heptane.

The test or reference fuel is put through a test engine with varible compression ratio. Pre-ignition vs comp ratio is characterised. If a commercial fuel is placed in the engine and it performs the same it is said to have the RON of the test fuel. So 98RON is called 98RON if it has the same resistance to pinging as the 98RON test fuel. Commercial fuels may not contain any Octane but can still have a RON.

So it follows that, if water even on its own has the ability to 'reduce' pre-ignition, it therefore increases the RON of the fuel. This is by definition and not opinion.

I would recommend trying WI. You wont get much power increase without changing ignition timing although after a while your combustion chamber and valve seat should be cleaner which may help. The big advantage with higher RON is the fact that you can run a fair bit more ignition timing. So on a stocker you advance the CAS...

I am currently working on a tunable WI unit that can be mapped to engine load via the afm voltage. The water will recirculate back to a tank via a cooler so it won't be heated by engine bay temp. A bit like how the fuel system works.

Also as someone else said, getting the atomisation of the water right makes a big difference. The reason for this is that the smaller water droplets, the more exposed water surface area you have and the more effective the water will be...It will cool much more effectively and also inhabit the combustion chamber much more evenly...

[CEF11E]

I have run water injection before in a turbo setup where there was no space for an intercooler. I ran a 50/50 mix and spray jet with a 43psi diaphram pump, anti drainback valve and pressure switch. it worked quite well I was able to run 13psi without pinging with it and only 6psi without,

I then played with it quite a bit and ended up using an injector distilled water methonol mix and the same 43psi pump. the injector was fired by the standard ecu injector driver on cyl #1 but would only fire once the afm read 2.95 volts. (this was when the car came on boost under moderate load.

this gave me a ratio of 1:6 as i was using the same size injector as the ones for the fuel. it worked really well but I had issues with the injector sticking as water is obviously not good for fuel injectors. it was a really simple setup. but there were 2 problems with it.

1. as boost rises you are LOOSING water pressure as the manifold pressure pushes against the pressure you are injecting. as 0 psi its 43psi at 10 psi its 33 psi ect... unless you use a rising rate reg hooked up to manifold pressure. never got that far before i sold the car.

2. if you ever forgot to fill the tank and you gave it a boot full the car would ping its tits off!!! happend to me more than once even though i had a reminder light installed on the dash.

[**RB2530**]

1. as boost rises you are LOOSING water pressure as the manifold pressure pushes against the pressure you are injecting. as 0 psi its 43psi at 10 psi its 33 psi ect... unless you use a rising rate reg hooked up to manifold pressure. never got that far before i sold the car.

Yep this is a known problem and thats why the WI kits use at least a 100psi pump.

Another way of dealing with it is to use a sealed water tank and pressurise it with boost pressure. The obvious problem is that your water tank must be able to withstand boost pressure, otherwise you will pop your tank apart...

I have tested a couple of those plastic red jerry can tanks. They must meet and an Australian Standard designated hydrostatic test. They must withstand 2.5bar for 30mins 2x or something like that. The trouble is in a WI application is the loading on the tank will be many, many more cycles and even if its only 1.5bar, after 1000s of cycles they may fatigue...

A fix may be to fabricate a decent stainless steel strap that holds the tank together...or get a decent fabricater to make a tank out of aluminium 3 or 4mm plate. I considered using an air receiver off the brakes on a truck but I think they are mild steel and may corrode due to the water..

[CEF11E]

yep the receiver is a good idea. I was going to a stainless tank welded up and use an intank pump with a decent volume air line feeding the tank from the manifold so it owould still fill quickly from vaccum to boost when it is nearly empty.

I have a freind that has a 12v air compressor from a truck air horn that feeds air into a pressurised tank from the top and the water pickup at the bottom. using an injector again but running methonol 80 water 20. the tank has a pressure switch that turns on the compressor as soon as pressure drops below the desired level. the whole system is really compact and works much better than most of the commercially available kits.

he is running mega boost. 40+ psi on a low compression gsxr1300 engine is his dethkart... I refuse to be a passanger

[**RB2530**]

yep the receiver is a good idea. I was going to a stainless tank welded up and use an intank pump with a decent volume air line feeding the tank from the manifold so it owould still fill quickly from vaccum to boost when it is nearly empty.

I have a freind that has a 12v air compressor from a truck air horn that feeds air into a pressurised tank from the top and the water pickup at the bottom. using an injector again but running methonol 80 water 20. the tank has a pressure switch that turns on the compressor as soon as pressure drops below the desired level. the whole system is really compact and works much better than most of the commercially available kits.

he is running mega boost. 40+ psi on a low compression gsxr1300 engine is his dethkart... I refuse to be a passanger

If you fed the receiver / water tank with pre-throttle body air the tank would never be under vacuum....And yeah the air over water idea is a good one too...I thought of using exhaust manifold pressure to pressurise a tank but don't know if the pressure difference would be big enough...It would depnd on turbo and exhaust design. Plus it could be very disastrous if water somehow got drawn into the exhaust mainifold...

[Daboss]

Ok only info I got was that the injector supports 500hp. Info i have for you is that my car is running afr's of 12 to mid 12's on stock turbo at 12psi. ALL I want to know is should a 50/50 mix of meth and water bring the afr's down? As I see no change when the injection suppose to have been injecting in the system.

[**RB2530**]

What you have to do initially is work out what the overall change in fuel entering the engine is when the Water/methanol injection is switched on...

When the WI is switched off you just have petrol entering...so rate of fuel flow will be 'very roughly' determined by injector duty cycle % x full flow number of injector (for standard fuel pressure). ie for stock RB25 fuel system = 375cc/min 43psi FP at 100% duty x 6 cylinders. At say 70% duty cycles this will be 375x6x0.7=1575cc/min. This = 1.16kg/min petrol.

If you are running 50/50 water / methanol by volume this = 60/40 water/methanol by mass and your WI nozzle is supplying the water/methanol mix at 200mL / min (for example) then the mass of methanol entering engine will be 0.2x0.4 = 0.08kg/min.

So the amount of fuel increase is not much at all. = 1.24 kg/min which is a 6% increase in overall fuel..

Now there are many assumptions made here. One main one is that all of the petrol and methanol burns...In reality it doesn't. Stoich for petrol is 14.7 afr so if you are running in the 12's not all petrol will burn. Also the methanol is soluble in water and i dont know if it burn when mixed with water...

So based on this my 'best guess' is that your afrs would change no more than 5%. Depending on what you are using to measure this change will be too small to measure..

Any chemistry gurus please feel free to comment...

[Daboss]

What you have to do initially is work out what the overall change in fuel entering the engine is when the Water/methanol injection is switched on...

When the WI is switched off you just have petrol entering...so rate of fuel flow will be 'very roughly' determined by injector duty cycle % x full flow number of injector (for standard fuel pressure). ie for stock RB25 fuel system = 375cc/min 43psi FP at 100% duty x 6 cylinders. At say 70% duty cycles this will be 375x6x0.7=1575cc/min. This = 1.16kg/min petrol.

If you are running 50/50 water / methanol by volume this = 60/40 water/methanol by mass and your WI nozzle is supplying the water/methanol mix at 200mL / min (for example) then the mass of methanol entering engine will be 0.2x0.4 = 0.08kg/min.

So the amount of fuel increase is not much at all. = 1.24 kg/min which is a 6% increase in overall fuel..

Now there are many assumptions made here. One main one is that all of the petrol and methanol burns...In reality it doesn't. Stoich for petrol is 14.7 afr so if you are running in the 12's not all petrol will burn. Also the methanol is soluble in water and i dont know if it burn when mixed with water...

So based on this my 'best guess' is that your afrs would change no more than 5%. Depending on what you are using to measure this change will be too small to measure..

I found out that my nozzle size is 500cc/min. Ok so the afr will basically not change at all, so all I can really do is advance timing a bit. I was thinking the afr's would drop a point or at least half a point and I would be able to lean it out a bit more with the safc. Also how much oil are we talking about adding to a 1.5 gallon tank. I also want to kno what is 12 still the safe afr to run even with the injection kit installed or can I go a bit leaner?

[benro2]

Two more interesting points I picked up off the performanceforums:

1. Injecting the water before the turbo can actually have the effect of shifting the whole compressor map to the right. So essentially, you can use a smaller compressor but have it act as a larger compressor when you're injecting water. I believe you can do this without any damage to the blades when the correct atomiser (ie: extremely fine water droplets!) is used.

2. Not sure about the reasoning behind this, but someone mentioned that if you run your car *leaner* than stoich (!) in combination with WI, you can actually make more power than richening the mixture as you do normally, without WI. So in other words, without WI, you richen the mixture not only to stop detonation, but it actually does make more power (up to a point obviously) than if it were running leaner (but well above stoich). So running leaner than stoich *with* WI, you'd be injecting massive amounts of water, plus you'd be running the huge risk of instant engine destruction if the WI ever failed. But still, interesting concept! Would like to find out why they think this works though...

Edit: I just re-read point 2 and even confused myself! I'll have to find the post again when I'm not as tired. I've probably missed something important in there...

Edited July 8, 2009 by benro2

[**RB2530**]

Two more interesting points I picked up off the performanceforums:

1. Injecting the water before the turbo can actually have the effect of shifting the whole compressor map to the right. So essentially, you can use a smaller compressor but have it act as a larger compressor when you're injecting water. I believe you can do this without any damage to the blades when the correct atomiser (ie: extremely fine water droplets!) is used.

2. Not sure about the reasoning behind this, but someone mentioned that if you run your car *leaner* than stoich (!) in combination with WI, you can actually make more power than richening the mixture as you do normally, without WI. So in other words, without WI, you richen the mixture not only to stop detonation, but it actually does make more power (up to a point obviously) than if it were running leaner (but well above stoich). So running leaner than stoich *with* WI, you'd be injecting massive amounts of water, plus you'd be running the huge risk of instant engine destruction if the WI ever failed. But still, interesting concept! Would like to find out why they think this works though...

Edit: I just re-read point 2 and even confused myself! I'll have to find the post again when I'm not as tired. I've probably missed something important in there...

Yep I agree with point 1. Compressor maps would be or should be based on dry inlet air at standard temperature and pressure which is 25degC at 1atm. So as soon as you add WI the evaporative cooling effect would drop the air temp and increase the air density and viscosity etc etc. Damage to turbine blades will always occur (even dry air will cause a bit of wear over a long period). Its all about the rate of wear or damage. Really fine droplets will have minimal impact on the blades.

The only problem is that the most common failure mode of a nozzle is that it gets partially blocked and the water does not atomise as it should. Good atomising nozzles run at very high water pressure. So if your pump fails partially or completely you will end up in scenario where the atomisation won't be right. When you switch your pump on or off the pressure wont rise instantly so you will always get situations where your atomisation wont be 100%. So IMO there still is a reasonable risk in adding water pre-compressor. It will largely depend on your WI setup.

[r33_racer]

There was a bloke on calais turbo forums who ran it pre turbo, and after a couple of years he was saying there was no noticeable wear on the blades....perhaps a billet compressor wheel could fix that over the standard type, if it were a problem. I believe he has a high pressure pump, along with a y piece valve that took boost pressure from the manifold and with the water pressure plus boost pressure it atomised the air even better then just straight water pressure....I believe this valve is easily bought, where from i dont know. I never looked into it much more.

But with it pre turbo, i believe he was able to squeese an extra 70-80hp out of it as it was flowing enough air as if it were a 800hp turbo, rather then the 700hp it actually was.

[**RB2530**]

There was a bloke on calais turbo forums who ran it pre turbo, and after a couple of years he was saying there was no noticeable wear on the blades....perhaps a billet compressor wheel could fix that over the standard type, if it were a problem. I believe he has a high pressure pump, along with a y piece valve that took boost pressure from the manifold and with the water pressure plus boost pressure it atomised the air even better then just straight water pressure....I believe this valve is easily bought, where from i dont know. I never looked into it much more.

But with it pre turbo, i believe he was able to squeese an extra 70-80hp out of it as it was flowing enough air as if it were a 800hp turbo, rather then the 700hp it actually was.

Yeah I have seen those nozzles. I think they are featured in an Autospeed article somewhere. These nozzles work on the same principle as a paint spray gun.

Also the comp wheel blade velocity reduces as you get closer to the centre shaft so if you are going to add atomised water pre-compressor you would try and aim the spary towards the centre of the comp wheel. BUT any water that hits the shaft /nut would bounce back and you would lose atomisation.

Also adding methanol would reduce the surface tension of the water and there atomisation would be better however menthanol may attack compressor wheel material after a while....interesting