Target Air/Fuel ratio - Kawasaki ZX-10R.net
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post #1 of 63 Old 04-27-2009, 10:32 PM Thread Starter
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Target Air/Fuel ratio

A buddy of mine has a 2009 zx-14 with a pcv with autotune,and ti-force full system.
Does anyone know the optimum a/f ratio #s 13/1 14/1 etc...
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post #2 of 63 Old 04-27-2009, 10:39 PM
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13:1 is a pretty good starting point for WOT A/F on a NA bike. It's aggressive, but pretty good. I've personally seen pretty good results off the dyno (ie: at the strip) with A/F's in the 12.5-13.0 : 1 range. Please note that those are only for WOT... not part throttle #'s. :)
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post #3 of 63 Old 04-27-2009, 11:23 PM
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For top speed contests I´d suggest 14-14.7/1, 800 rpm prior peak hp upto rev limiter (again, on a non turbo motor)
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post #4 of 63 Old 04-28-2009, 12:41 AM
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Air fuel ratio?

to be safe 12.1:1-12.7:1 is slightly rich, i mean slightly. This way you wont burn holes in pistons. 14.1:1 is lean period. my dyno guy shut my run down at 9000 rpm's cause he didn't want me to blow my motor on the dyno. Google the word "stoicheometric" it is the optimum A/F ratio for an internal combustion engine. Then you can form your own opinion about what A/F ratio you want for your bike
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post #5 of 63 Old 04-28-2009, 09:51 AM
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tune to 12.9-13.0 to start that should get you close.
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post #6 of 63 Old 04-28-2009, 11:21 AM
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Quote:
Originally Posted by BIGBADBRY View Post
to be safe 12.1:1-12.7:1 is slightly rich, i mean slightly. This way you wont burn holes in pistons. 14.1:1 is lean period. my dyno guy shut my run down at 9000 rpm's cause he didn't want me to blow my motor on the dyno. Google the word "stoicheometric" it is the optimum A/F ratio for an internal combustion engine. Then you can form your own opinion about what A/F ratio you want for your bike
As a matter of fact, did YOU googled the word stoichiometric?
Do you know what the A/F ratio is at that point?
Is 14/1 leaner or richer than the stoichiometric A/F ratio?

Please, don´t get confused and translate that to other people and DO your homework first, rather than thinking you are correctly reproducing what your tuner said.

Best power ratio is around 12.7/1, but that ratio won´t give maximum achievable top speed. Going towards stoichiometric will.

Last edited by sextaafondo; 04-28-2009 at 11:23 AM.
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post #7 of 63 Old 04-28-2009, 12:00 PM
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Quote:
Originally Posted by sextaafondo View Post
Best power ratio is around 12.7/1, but that ratio won´t give maximum achievable top speed. Going towards stoichiometric will.
.......I have to know how tuning OUTSIDE of the "best power ratio" will give more top speed?

Regardless, the bike in question will pull the stock gearing to the limiter (if it's unrestricted) all day long. Running the bike lean @ WOT on the rev limiter to get a mph or two that it has no gear for is, well, stupid.

Listen to Vince if not me... that guy knows what he's talking about.
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post #8 of 63 Old 04-28-2009, 12:30 PM
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Well... you´ve heard about flame speed?

You can achieve up to 10mph by leaning the last 800rpm. Of course, you don´t want to go further than 14.7 (and is useless and from that point onwards the engine is at risk)

The fast guys know this.
Perhaps you might want to give a try and you will notice that your bike goes far beyond that GPS # where it previously stuck.
You think 14.7 is risky.. ok try 14.

Again, no turbo motor.

The 08/09 10R with full exhaust (no PC3/V) is running pretty close to stoichiometric at WOT close to the rev limiter, and are doing GPS197mph with +1front/-1rear every day.

And...this is not a knowleadge contest. I know what Vince knows and he is right. What I said does not invalidate what he said, in fact I fully coincide.
I just added some point that is not usually given out. Take it or leave alone.
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post #9 of 63 Old 04-28-2009, 01:56 PM
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stoicheometric is where it will get the best combustion and is a general term that changes with selected fuel use. methanol is around 6.4:1, ethanol is around 9:1, e85 ethanol is around 9.8:1 only problem is that most of us are using an A/F sensor that is calibrated to gasoline. best power usually occurs at around .88 to .89 lambda which on gasoline is around 13 to 1.(14.7 x .88) on e85 like I run in my gsxr .88 lambda is around 8.6 to 1 but will still read 13 to 1 on most a/f gauges because the gauge is taking the lambda reading from the sensor and converting it to an a/f for gasoline. some A/f meters allow you to change the fuel that it uses for its calculation. anyway enough of that, many things effect a/f so there is no right answer but from my time on the dyno I have found that a good place to start to tune to on pump gas and many of the VP race fuels is around 12.9-13:1. on e85 ethanol around 12.6-12.7:1. all of these readings are taken on an A/f meter calibrated for gasoline. 12:1 is way too rich and will probable cost the bike 10+ hp on a naturally aspirated engine. turbo and nitrous will be very happy and safe at 12:1 but not a NA engine. And also I have never seen a NA engine burn a hole in a piston because it was too lean, a nitrous or turbo engine yes but cant see it on a NA engine. your best bet is to take it to a compitant tuner and you will know its right.

Last edited by Vince10R; 04-28-2009 at 02:01 PM.
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post #10 of 63 Old 04-28-2009, 01:56 PM
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.....how am I (or this guy) going to get 10 more MPH on a bike that already hits the limiter in 6th gear... by leaning out the last 800 rpm?

I mean really... let's think about this: an extra 10mph --in addition- to the 190 or so my 06 does at sea level on stock gearing with a big tire on it (and it's still pulling into the limiter...). Leaning out my mixture a full point and a half would give me a 200+mph on a stock bike IF I did have the gear to get there? How much HP do you think that is that you're picking up by going lean like that? And is it honestly worth the risk/complication for a street driven vehicle that sees the limiter in 6th maybe a handful of times per year? That's just plain bullshit. Show me a dyno graph, or anything that coincides. All my graphs and real world testing show otherwise. I HAVE run it back-to-back AND on the dyno: the bike likes it fatter. It picks up 1/4mph and still pulls all the way through 6th. It sure as hell didn't pick up enough hp "in the last 800rpm" to go 10mph faster @ 190ish mph when it was lean. It didn't lose a damn bit of hp when we took it from 14.2 to 13.0... and it went faster in the 1/4 by 1-2mph at 12.5:1 vs 13:1 (dyno #'s, all those).... though I still don't know exactly why.

"The 08/09 10R with full exhaust (no PC3/V) is running pretty close to stoichiometric at WOT close to the rev limiter, and are doing GPS197mph with +1front/-1rear every day."
----show me the same run(s) with the A/F cranked down to the low 13 range and show me that it actually goes slower. I'd like to see that.

...and we're not talking about speed trials here anyway... we're talking about a good, strong, SAFE street AUTOTUNE that the guy can set his bike to and forget about. Even IF (big if here) you're right, it's about usless to this guy anyway. We can all appreciate some pedantic input/bench racing here and there, but this guy wanted some real world info... and it's just responsible to give advice to strangers with a safety margin added in. I sure don't want to be the guy that gave him the aggressive advice and he ends up fragging the top of the piston @ 170+mph because he had a bad load of pump gas. Common sense man.

Last edited by SpazOnaZX; 04-28-2009 at 02:01 PM.
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