Calculating my fuel flow- working out water inj jet size

[StavFC]

I do suck with maths, I wont try and deny that :Laugh:Hammer
 
I am trying to work out a rough jet size for my water injection, and they usually say 10-25% fuel flow, depending on how much you are depending on it.
 
Anyone know the rough fuel flow of a T04E\'d street ported 13B thats meant to have about 350-400bhp? :xconfused:confused::3Confused

[StavFC]

Doing my basic retard maths and guestimations by how rich rotaries run, I reckon something along the lines of 2.4-2.7 litres of fuel per min for a 350-400bhp 13B at full howl? Or is that not enough?

[Prof]

Some places rate the nozzles by HP - that will work just the same for Rotaries.
 
I plan on running similar power to you and have an Aquamist 0.6mm nozzle and pump will be set to 150 psi max (cooling mist pump).  You may need a spark amp though, as the water will quench the charge and tend to put the spark out.

[StavFC]

I dont want to rate by HP, I want to know by CC/ML.
That HP thing wouldnt work with rotaries really if calculated on a piston engine, it wouldnt be THAT accurate anyhow, as it depends on the AFR and BPFC of that particular engine, and thats very different on a Rotary to a piston engine.

[Prof]

No offence, but the power the engine produces is directly proportional to the fuel/air it uses.  Yes rotaries have a longer combustion chamber and are consequently less efficient than the piston engine at combustion, but both a rotary and a piston engine will be similar in fuel consumption for similar AFR\'s at similar power levels.
 
As you only want water injection when you hit higher boost, and will probably be running the injectors close to 80-85% at that point, you can use one of the injector calculators to work out your flow at a given HP then decide how much water you need.  Unless your eeking out the last ounce of performance from your engine with WI (and therefore tuning for it) it really isn\'t that critical how much as long as it doesn\'t swamp the engine.

[StavFC]

Simple fact is, regardless of anything else, rotaries often run far richer AFRs on boost compared to piston engines, so its NOT the same as using piston engine calculations.
 
I dont want probably or guesses made from piston engines, I already made a guestimate closer than that, I just wanted to know, in real numbers, from someone who I expect is better at maths and better at rotaries than me, the fuel flow at full wack what your average 350-400bhp rotaries use.
 
I cant check injector duty to be 100% sure even if I had injector sizes, and nor can anyone unless they got an ECU that can show them, but I\'d hoped someone here might know enough about their engines or just a bit of maths to give me a close enough number.

[BlitzBoy]

What ECU are you running that you cant check Injector duty?
What Water Injection system are you using, from there I may be able to help?

[Prof]

Simple fact is, regardless of anything else, rotaries often run far richer AFRs on boost compared to piston engines, so its NOT the same as using piston engine calculations.
 
I dont want probably or guesses made from piston engines, I already made a guestimate closer than that, I just wanted to know, in real numbers, from someone who I expect is better at maths and better at rotaries than me, the fuel flow at full wack what your average 350-400bhp rotaries use.
 
I cant check injector duty to be 100% sure even if I had injector sizes, and nor can anyone unless they got an ECU that can show them, but I\'d hoped someone here might know enough about their engines or just a bit of maths to give me a close enough number.

Perhaps it would be better if you give us some real world figures - such as what injectors you are running - what engine, what mods - then perhaps doing some more involved maths might make more sense.  350-400 is quite a range ! :rolleyes:
 
Are you using the WI as a safety net, or will you be tuning for it ?
 
Perhaps if your question were phrased better you might have got a better answer.
 
For instance - if you tune for WI, then it\'s quite acceptable to drop the fuelling when the WI comes in, as you can run leaner to get more power knowing the water is there to lower the onset of knock.  But if you are going to use it like that - you\'ll need to be very precise about what your injectors are doing - and if you don\'t have an ECU that can show you that, then you\'re already stuffed and need to sort that first.
 
and for the record - Stoich is stoich for petrol/air combustion - regardless of what type of engine - and as you make the most power at/close to that point - getting as close to it is the art.  A lot of people run their engines far too rich and sacrifice power, but with a rotary it\'s easy to lean out and go bang if you aren\'t sure what\'s going on.
 
Not trying to diss you - but perhaps some more info might help ?

[StavFC]

Running F-Con.
 
And its not quite a range, as said, I estimated 300cc more a min difference between those two powers (50bhp) in fuel, so about 30cc difference of water/meth if talking 10%, thats not "quite a range", thats as near as damnit spot on, unless you reckon you could get more accurate than being half a ml out a second prof? lol.
 

Stoich is stoich for petrol/air combustion

Who in their right mind on ANY performance car runs stoich or anything close at peak power? What a bizzare thing to say.
 
Seems to me you are just arguing just to be clever/right now, and on that note, I give up on this thread, useless with replies like that, ill find out elsewhere somehow.

[Prof]

Try one of the WI forums....
 
:wave

[Prof]

Try one of the WI forums....
 
:wave

You could try this - for rotary applications double the capacity (2.6L)
 
http://www.alcohol-injection.com/forum/nozzle-size-calculator/

[AtomicRex]

Ouch....Prof...consider yourself bitch slapped! lol

[Prof]

Ouch....Prof...consider yourself bitch slapped! lol

Don\'t worry - I suspected as soon as I saw the reply that it might have been the said same Stavros that I\'ve had dealings with on another forum - but never mind - we try to be helpful, he is a rotary owner after all :Thumbs-up

[Nik da Greek]

Ah, yes, the most opinionated, rude, abrupt and know-it all person ever to log on any forum ever, (no, I don\'t mean Prof! ) and the reason I stopped buying Redline magazine cos I couldn\'t stomach reading his pretentious invective every month. Maybe we could take his attitude more seriously if he hadn\'t publically taken apart every single "project" car he\'s ever had in the quest for building a "drift monster" and then utterly failed to ever put it back together and finally quietly sold it on as parts and moved on to murdering the next perfectly good performance car?

[BlitzBoy]

ahh so this Stav Guy is a writer for Redline magazine?

Well he would need to take his car to tuner as he has an FCON anyway to have it retuned if he is tuning for water, as official HKS tuners are the only ones to have the software and dongle I think to read the ECU.

StavFC if ya still reading you didnt answer what AI system you have , if it is an aquamist system talk to Richard on the Aquamist forum he has made the best systems for Rotaries at the moment and will give you the precise answers you require.