WHAT AM I LOOKING FOR ON MY A/F RATIO

[THE ICE MAN]

I want to make sure i am going to be doing this right.
I am installing on a 1300cc engine with 10.5 to1 compression
and will be running 6 and 9 lbs of boost on high.
My question is do i tune it to 12.5 to1 without the water injection
then put water on, or do I tune it to 12.5 to1 with water inj.
If I tune it to 12.5 to1 without water inj. what will I see on my AFR when I turn the water inj. on?
I have a .5mm jet.
I will be running 50/50 pump and race gas at 105.5 octane
Thanks alot guys.

[THE ICE MAN]

One more thing this will be used for1 mile drag racing.
if there is two different a/f ratios 1 for street and 1 for track let me know
Thanks again.

[JohnA]

My understanding is that you can run leaner with the W.I. working.

In any case I wouldn't trust the AFR readings while WI is operating, kinda like nitrous. So I'd set the fuelling without the WI operating.

Is that a Hayabusa? :P

[THE ICE MAN]

John,
Yes a hayabusa and a gsxr1000
Set it at 12.5to1 then turn on the water?

[JohnA]

Have you got stock pistons/gasket?

Your conservative boost setting would indicate so anyway :wink:

[THE ICE MAN]

The 1000 motor I just finished, it has stock pistons, the stock comp, was 12.1
I lowered it to 10.5 to1

The hayabusa is not ready yet that one will have turbo pistons and spacer plate set at 9.0 to1 and will run higher boost 15-20 lbs

I still need to know at what A/F ratio I should use with & without water?

[JohnA]

...I still need to know at what A/F ratio I should use with & without water?
It depends on the Comp Ratio, among others.
If the CR has been lowered enough (relative to boost levels) then you can run a bit leaner than otherwise.
With W.I. you can run a bit leaner still.

As a rule, with crap intercooling and inadequate CR lowering, AFR of 11:1 is a good idea
With good intercooling, low CR you can aim for 12:1
With W.I. on top, you're looking at 12.5-13.0:1 perhaps.

Of course cam timing, fuel quality and ignition timing will also affect things.

[THE ICE MAN]

Thanks John.
Any other replies welcome
I am trying to achieve at least 205MPH in less than 1 mile
on a 1000 suzuki with 230 H.P.

[hotrod]

I sent you some stuff on this in answer to your PM, but in general you can run significantly leaner with adequate ADI ( sorry guys I prefer the air craft term of antidetonation injection because mixtures of water and alcohol can vary so much from user to user and folks seldom run just pure water).

If you have a quality AFR meter, then I would suggest you get a good max power tune dry and then add the ADI and see how the meter records the change in AFR. Then try a couple different mixtures of water and methanol, and see what happens.

I have seen some debate on how a meter will be effected but I have not seen anyone actually get experimental data.

You may not be able to get absolute fuel air ratios but if you know how much it is effected by the injectant mix you run you should be close enough for tuning purposes.

You may also want to touch base with the guys at RBRacing.
http://www.rbracing-rsr.com/bonneville2.htm
They seem to know what they are doing with this sort of thing.

Larry

[THE ICE MAN]

I checked out RBR racing and according to their chart they want to see a 12.5 to1 without water and then somewhere around 10.5-11.0 afr with the water injection based on 15-22% water injection
They say 12.5 to 1 air fuel
and 10.5 -11.1 AIR to (FLUIDS) RATIO water and fuel
They do the salt flats thats 2-3 mile runs!
and i am sure they went thru plenty of motors for their research

we are currently running a turbo 1000 now with stock compression
12.1 and we set the air fuel to 11.3-11.5 with 105.5 octane
minus 2 degrees timming
with myself as pilot i went 201.1 MPH in 9/10's of a mile

Heres were i dont know how far to push it
new bike 10.5 comp. and water inj
so maybe i can go a litle leaner than 11.3-11.5 with water??
or have my target 11.3-11.5 with water
Velocity racing does turbos for bikes i think they had problems at the begining setting them up in the 12. ? to 1 range without water on a 1 mile run so they went to the 11.3-11.8 range without water and everything was good.

[THE ICE MAN]

O.K. I talked to 2 guys on the board that have good knowledge and experience on water injection and will try some of the things we discussed
I am looking to get this bike at least 205 MPH in 9/10's with the motor making a reliable 230 H.P.
Putting the motor in tommorow will tune in next week, and keep you updated.

[Richard L]

There is water injection Hayabusa currently running water inejction on the 200mph.org site.

I will try to invite him over here to help answering some of your more involved questions.

[mx5]

They say 12.5 to 1 air fuel
and 10.5 -11.1 AIR to (FLUIDS) RATIO water and fuel


Huh?!? You think 20% water to fuel, can move your AFR from 12.5 to 10.5 ..... ? this just doesn't sound right. have you tried calculating whats your Air to Water ratio?

I think you got it the other way around. 10.5-11.1:1 WITHOUT water and 12.5:1 WITH water, since with water you don't need that extra fuel for cooling the cylinder walls ...

[JohnA]

They say 12.5 to 1 air fuel
and 10.5 -11.1 AIR to (FLUIDS) RATIO water and fuel


Huh?!? You think 20% water to fuel, can move your AFR from 12.5 to 10.5 ..... ? this just doesn't sound right. have you tried calculating whats your Air to Water ratio?

I think you got it the other way around. 10.5-11.1:1 WITHOUT water and 12.5:1 WITH water, since with water you don't need that extra fuel for cooling the cylinder walls ...

Ah, but the second one is air to FLUIDS ratio. So fuel is effectively less than before.
Interesting take on AFR, but it assumes a linear relationship between fuel reduction and water mixtures added. I wouldn't be so sure about this one.

[mx5]

Ah, but the second one is air to FLUIDS ratio. So fuel is effectively less than before.
Interesting take on AFR, but it assumes a linear relationship between fuel reduction and water mixtures added. I wouldn't be so sure about this one.

Yes, and that's what I told to calculate. Now get the calculator and check how much replacing 1.5% of air with fluid (roughly, assuming about 20% of fuel injected water) changes your air to fluid ratio in a 12.5:1 air to fluid mixture ... Changing 1.5% of the air with water doesn't make the air to fluid ratio to 10:1, at least according to my calculator ;)

[hotrod]

Ratios and proportions are always fertile ground for confusion, because there are so many ways to interpret them especially if they are stated as word problems rather than a math formula.

Lets put some numers on this and see what comes out, based on how I am reading this.

Assume:
1300 cc engine displacement, and 6 - 9 psi boost with an assumed VE of about .90. Just to pick an operation point lets say 8000 rpm.


That would give a swept engine volume of about 213 CFM at .90 VE or 192 CFM of air at a manifold absolute pressure of 23.7 psi ( pressure ratio of 1.61) for a true air flow of about 310 CFM or about 21.7 lbs of air/min.
(sorry guys I grew up with imperial units ;) )

At a 12.5:1 air fuel ratio (by mass) you would need 1.736 lb/min of fuel, if the WI rate is at 22% of fuel,(the max recommedation) then you have 0.38 lb/min of injectant.

Your total "fluids to air ratio" becomes 21.7 : (1.736 + .38) or 10.255:1.

At least that is how I am inerpreting the recommendation from the RBR calculator.

Larry

[Richard L]

Water to fluid ratio is quite straight forward to calculate

But if you want specifically on the cooling effect due to evaporation, you need to take the latent heat of each liquid into account and re-calculate to that effect.

Some time ago I have made a chart up to show how much water is require to replace the rich-air/fuel ratio, here it is again - It was done quite quickly and do point out any mistakes plaese:


http://www.aquamist.co.uk/forum/afr.jpg


This one I have included 25% of merthanol:

http://www.aquamist.co.uk/forum/afmr.jpg

[Richard L]

If the chart is correct, it appears that all you need is 3% water/fuel will replace two points of afr (10-12.5).

I'd better explain how the chart was calculated:

Without water:
10Kg air + 0.95kg fuel = 10.5 afr
.
.
.
10Kg air + 0.80kg fuel - 12.5 afr



With water
10kg air + 0.95kg fuel + 0.00475kg = 10.5 afr + 5% wfr
.
.
.
10kg air + 0.95kg fuel + 0.095kg = 10.5 afr + 10% wfr

Substitude the latent heat of each liquid and plot the result with excel.

Latent heat of fuel = 350KJ/kg
Latent heat of Methanol = 1109 Kg/kJ
Latent heat of water 2256KJ/kg