Water/meth injection: a theoretical and practical discussion

[jimGTS]

it wont be of equal flow.

for this same reason its why people uprate there inlet manifolds, to get equal and/or more gas flow to each cylinder.

cylinder 3 i believe is known to be the weakest link for flow on the stock manifold, hence why people normally add a little more fuel to this cylinder.

least that was my understanding.

[2mad]

Cheers Jim , Thats defiantly given me something to think about.


Nearly got all the parts to go fmic (st205) and w/m on my new setup, pray i get it right
Will post my findings .

[bobhatton]

OK, thanks for the tip, I'll have a look at the mani later today to see what's feasible.

Would you suggest mounting the nozzles in the top of the plenum pointing down the runners? - Or in the runners themselves near the top?


I have no system in mind yet, but as always cost will be kept to a reasonable minimum.
I've got a long time before the car will be ready, so planning to bide my time and wait for a good quality recirculating pump to come up for sale second hand, then build the rest of the system up from there.

In the runners only.

Here you are, everything you will need from one place.

http://www.coolingmist.com/pagedisplay. ... re_Key=all

Bob this ones for you (I know i've been playing devils advocate) and am quite happy with tfs's theory .. But heres my question, spraying 12 to 15" before the throttle body (rev3) what sort of flow (w/m) per cylinder do you think im getting from each runner . Do you think its an equal flow of w/m


Do you know for a fact one of the four runners could have restricted flow compered to the others , because its a dry manifold

This question is more important to me than if w/m cools intake charge.


Kev.


Ps. w/m = water/meth

If I said to you please remove your 4 fuel injectors and just use one in the pipe work from the intercooler, would you be very happy with that?

[2mad]

In the runners only.

Here you are, everything you will need from one place.

http://www.coolingmist.com/pagedisplay. ... re_Key=all

Bob this ones for you (I know i've been playing devils advocate) and am quite happy with tfs's theory .. But heres my question, spraying 12 to 15" before the throttle body (rev3) what sort of flow (w/m) per cylinder do you think im getting from each runner . Do you think its an equal flow of w/m


Do you know for a fact one of the four runners could have restricted flow compered to the others , because its a dry manifold

This question is more important to me than if w/m cools intake charge.


Kev.


Ps. w/m = water/meth

If I said to you please remove your 4 fuel injectors and just use one in the pipe work from the intercooler, would you be very happy with that?

Good point, cant argue with that Bob . Does a rev3 manifold really flow w/m that bad if im tuned for 11.5 afr w/m off it will cause me problems

[bobhatton]

Unless you fit a O2 sensor in each exhaust port all you are going to read is the average of all four cylinders, so you will never know if one is running lean and the other 3 are running rich.

11.5 afr is lean for a turbo engine unless you have a large amount of intercooling or on high octane fuel.

[2mad]

Unless you fit a O2 sensor in each exhaust port all you are going to read is the average of all four cylinders, so you will never know if one is running lean and the other 3 are running rich.

11.5 afr is lean for a turbo engine unless you have a large amount of intercooling or on high octane fuel.

I was running 11.5 afr w/m off on my last build , 10.8 afr w/m on but like you said "you will never know if one is running lean and the other 3 are running rich" Cheers Bob something more for me to think about .

Kev.

[2mad]

Must admit i'm coming round to Bob's way of thinking, question, running 4x0.3mm jets one per cylinder, what if one jet clogs how would I know . It does happen and could be the death of my engine, running one 0.7mm jet if it clogs my wideband would tell me straight away.
Plus how do I run 4x 0.3mm = 1.2mm of jet flow at the 0.7mm of flow I need, if you see what I mean .

Kev.

Ps. got my st205's fmic for my water/meth injection project today, cores 600mx300x100mm its massive

[ashley]

If one jet clogs, that cylinder would run leaner (assuming you're injecting meth) so your wideband should still warn you, it just won't be as obvious as if all 4 ran lean at once and you'll have to do some work to find out which one was blocked...

[bobhatton]

Must admit i'm coming round to Bob's way of thinking, question, running 4x0.3mm jets one per cylinder, what if one jet clogs how would I know . It does happen and could be the death of my engine, running one 0.7mm jet if it clogs my wideband would tell me straight away.
Plus how do I run 4x 0.3mm = 1.2mm of jet flow at the 0.7mm of flow I need, if you see what I mean .

Kev.

Ps. got my st205's fmic for my water/meth injection project today, cores 600mx300x100mm its massive

You have to filter what ever you inject into the engine just the same way as the stock fuel is.

You need to be working with flow not a hole size.

[ashley]

Doesn't hole size dictate flow?

[Nails]

Id imagine its down to pressure too. Just like injectors? A hole will dictate flow accordingly to gravity. Up the pressure and you'll get more through?

[Nails]

Id imagine its down to pressure too. Just like injectors? A hole will dictate flow accordingly to gravity. Up the pressure and you'll get more through?

[ashley]

Agreed, but the pumps we tend to use with water injection aren't variable pressure are they? (They might be, I just assumed they weren't)

[JAAASH]

Mine isn't adjustable. Pump just states its 200psi. (Cooling mist kit)

[ashley]

Thinking about it though - the controllers vary the voltage to the pump (I think), which I guess would vary the speed the pump runs at, and so vary the pressure/ flow rates achieved.

So with larger nozzles you'd dial down the voltage to compensate and reduce flow...but presumably you'd have lower pressure at the nozzle and so less effective atomisation.

[2mad]

Thanks for all the responses
I triple filter my water using reverse osmosis (you can just buy distilled) down to 5 microns and have two filters on my w/m injection system again filtering down to 5microns. Its just a 0.3mm jet is so small I really would worry about it clogging I guess my wideband would pick it up but it would not be blatantly obvious like my 1x0.7mm jet failing (i dont think?)
Remember I have no way of knowing how well filtered the 50% methanol is I mix in with my water is (if it is even filtered)

As for flow .. on my 1s system its done by jet size the pump flows at a fixed rate, I was really hoping Bob was going to say theres a regulator or solenoid I could buy to drop pressure, I really didn't want to have to buy a hole new setup just for adjustable flow



Kev.

[2mad]

Thinking about it though - the controllers vary the voltage to the pump (I think), which I guess would vary the speed the pump runs at, and so vary the pressure/ flow rates achieved.

Cheers ash, great idea. I will check the net today

Hope my aquamist race pump can even flow enough for 4 jets .

Lots to think about, really do want to try Bobs setup this time round, I just seems to have a few more obstetricals to overcome.


Kev.

[bobhatton]

Plus how do I run 4x 0.3mm = 1.2mm of jet flow at the 0.7mm of flow I need,

Are you sure 4 x 0.3 jets = a 1.2mm jet?

How do you know 0.7 mm gives the flow you need?
How are you determining the flow you need?

[2mad]

Plus how do I run 4x 0.3mm = 1.2mm of jet flow at the 0.7mm of flow I need,

Are you sure 4 x 0.3 jets = a 1.2mm jet?

How do you know 0.7 mm gives the flow you need?
How are you determining the flow you need?

Lol you've really put me on the spot here, I lost my notes from a couple of years ago and my memory is awful.. but i'll have a crack at it.. it goes something like this...


On my old car..
4 x 440cc injectors = 1760cc

1760 x .85 = 1496

15% of 1496 = 224.5cc

On this chart .. http://www.aquamist.co.uk/forum/flowrate4.gif

224.5 = 0.6mm jet but you go up one if your running meth =0.7mm jet


For 540cc injectors I have now..

4 x 540cc injectors = 2160cc

2160 x .85 = 1836

15% of 1836 = 275.4cc

On the chart above 275.4 is between 0.7mm and 0.8mm so I really should round up to a 0.8mm.

So to run 4 jets I need a 0.3mm jet to flow 68.85cc or thereabouts.

Still researching 0.3mm flow rates at the mo but I think there around 155 cc/min way to high

[Lefty1991]

I've been thinking about water injection for my rev3 turbo. I'm using an arc smic running 1.2bar boost. After a few pulls my Inlet temps reach about 50-55 degrees. So I have a couple of questions
1. Will running water injection drop these temps?
2. I don't want to map the car again for water/meth say a 75/25 mix, will it run alright?
3. Would mounting the jet in the IC cold pipe be alright?
Cheers for any advice