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Target Air/Fuel ratio

33K views 62 replies 17 participants last post by  famishiko 
#1 ·
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...
 
#2 ·
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. :)
 
#4 ·
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
 
#6 · (Edited)
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.
 
#8 ·
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.
 
#9 · (Edited)
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.
 
#11 ·
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. your best bet is to take it to a compitant tuner and you will know its right.

That's awesome info Vince.... I didn't know that one about how they figured out the A/F for lambda. :) Maybe that's why Ivan likes runing CO2 readings instead of A/F, eh?
 
#10 · (Edited)
.....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.
 
#13 ·
:crackup: I don´t have to tell you forget everything I said.

Perhaps if you read this comment of mine that seems ridiculous to you from another member, you will take it into account.

Just to extend a little bit more the topic, you can´t see the advantage of this A/F ratio on the dyno.
As a matter of fact you can probably see a very slight drop in power, but as the bike is accelerating on the dyno (as it does in the 1/4 mile) you´ll need a fatter ratio to show best power (and accelerate faster).
Once acceleration is not necessary (at 190mph) you can take advantage of the faster flame front inside the combustion chamber, of leaner ratios.
Fatter ratios achieve good power and best acceleration times, but not best top speed.

Then, if you´re hitting the limiter in 6th, continue to drop teeth at the rear until you don´t anymore.
Best 2nd gens here are doing are doing GPS 198mph without internal engine work. You may think that this is pure :bs:, but it´s not. (about the same the 3rd gen does without Pcommander)
08-09 GSXR1K are doing GPS 203mph without the hell of a work.
In every case lambda sensors showing around .76 / .75V close to rev. limiter.

That means something is being done right down here, and in no case, as I consider myself not to be any kind of moron, I will throw here some false info (not even "in doubt" info)

As Vince says, best power is get from a .86V lambda reading. Completely agree with that and the rest you said Vince. Really good post.:thumbsup:
 
#15 ·
autotune #s

My buddy with the 09` zx14 just finished riding/auto tunning his zx-14,so we opened up his pcv with my labtop to take a look at the a/f #s the auto tune gave,they ranged from 13.4 to 13 all across the map.The 80-100 columns were 13.
We also did a few roll ons 40mph-120ish,and the auto tune really made a big difference in his mid-range,for the first ever I had to catch him and i did right around 80-90mph.
 
#24 ·
The GSXR speed limiter is real here too. Guys have a switch at the handlebar to manually set the bike into a false 5th, once in 6th gear.
Setting the bike all the time in 5th (with a TRE) proved to make the bike slower in acceleration, so most everyone in this mod just put a manual switch.

As I said, at least the series arriving here, the 10R hasn´t this rpm or speed restriction. :thumbsup:
 
#25 ·
Yeah tre is no good, people dont realize that the ecu will add fuel to compensate for ram air by gear and when you tell it its in fifth when its in first it will not run correctly. we changed mine inside the ecu by reprograming the actual ecu rev limiters. If I get to dyno a 10 I will run it in sixth also to verify the US version doesnt have it. :thumbsup:
 
#27 ·
responsible guys, last 2 posts above me :+2: well said.

so heres a completely different question all kinds of off topic. Im a smog tech in california, i dont mean a monkey with a wrench claiming to be a mechanic... i mean a diagnostician.
...
BUT, never dyno tuned bikes... do moto motors really melt/frag/burn at 14:1? almost all our cars out there are running 14.7:1. if it has an 02 or an A/f on it... 14.7:1 with exception, some of the hondas are running 22:1 not kidding. why is there this discrepancy, and please dont write back some simple stfu truck bs like "cause its harder" gimmie some numbers, wach the throttle on your whatever commuter car and it wont blow at redline. srsly, im at a loss what this fuss is about(once again, no dyno tune expeirience to gain power, normally im gaining emmession quality)
familiar with lambda, stochiometry and hexidecimal.
 
#28 ·
No way it melts at 14:1 unless its nitrous or turbo.(these like to be around 12:1 for safety and power) You could probably run it to 16:1 without melting it on a naturally aspirated engine.(not that I would but you probably could). Is the honda 22:1 under full power? also could they be pumping air downstream to help the converter out?(this would give a false reading in the exhaust but in the cylinder it would be the correct mixture. also all of these bikes will go to 20+ to one on decel after closing the throttle abruptly. :thumbsup:
 
#40 ·
The other thing with the Bazzaz (and I'm not sure it is the case with the Power Commander 5) is that it can auto-tune to a set air/fuel ratio but it looks for the same ratio everywhere in the map, which is not correct.

Solution, set it to 13:1 (or whatever) and accept all the changes near full throttle but not below. Set it to 14:1 and accept all the changes at moderate load only. Set it to 15.5:1 and accept all the changes at light load only.

This is still a bit tricky, because "throttle position" isn't the same as "percentage of maximum torque output" - not even close - but I don't think the mapping allows for that. What you really want is probably something like 13:1 above 80% load, 14:1 at 60% - 80% load, and 15.5:1 (for best fuel consumption) below that ... but 80% load is a small fraction of throttle opening at low engine RPM ...
 
#41 ·
The other thing with the Bazzaz (and I'm not sure it is the case with the Power Commander 5) is that it can auto-tune to a set air/fuel ratio but it looks for the same ratio everywhere in the map, which is not correct.

Solution, set it to 13:1 (or whatever) and accept all the changes near full throttle but not below. Set it to 14:1 and accept all the changes at moderate load only. Set it to 15.5:1 and accept all the changes at light load only.

This is still a bit tricky, because "throttle position" isn't the same as "percentage of maximum torque output" - not even close - but I don't think the mapping allows for that. What you really want is probably something like 13:1 above 80% load, 14:1 at 60% - 80% load, and 15.5:1 (for best fuel consumption) below that ... but 80% load is a small fraction of throttle opening at low engine RPM ...
 
#43 · (Edited)
Hate to re-open a thread but got a curious question. I had my bike up on a dyno here last week and with the new collectors and stacks it leaned it out more than I thought it would. Was pulling right around 15.1 all the way. If it laid down 163.66 what would you guys estimate it at proper A/F?



Was cool though, a brand new VMax with 1800 miles on it, running half pump gas/half VP110 made 167.50. I was also running 25-28 psi in the rear, the operator said it was slipping a little but I didn't notice that, I just don't think he realize the bike has a pretty strong pickup around that speed.

Oh, sextaafondo, the bike did hit a higher speed this time around...I think it's safe to say you can get past the top speed restriction here as well, I just have never seen it verified.
 
#44 ·
Question ... Did you block off the air-suction valve (the gizmo above the cylinder head that lets extra air into the exhaust ports)? If you don't do that, you will get a false lean reading.

I don't think there is any way you really pulled that much power running that lean.
 
#45 ·
Ivan's block offs put on a year ago, there is a thread with all my mods. I can scan the sheet if you'd like but I don't think it's going to matter huh?

Remember also that VMax's are shaft driven...aren't the parasitic losses greater with shaft driven bikes compared to chain/belt?
 
#48 ·
Yes; since the time of that post it has been learned that you can set individual target air/fuel ratio cells in the PC5.
 
#52 ·
guys i fitted a wideband lambda kit to my 06 10,i have a full akro and the bosch lsu 4.2 sensor is fitted in the factory boss that akrapovic puts on there system,it is in the part of the exhaust that is single pipework so it gets all avaliable gases..when i had it on the dyno(dynojet 250i)the dyno guy fitted a new pump filter to his dynojet gizmo,put his sensor down one of the exhaust cans!when it was run up my air/fuel gauge was reading eg;13.6 when the dynojet screen was reading 14.0/14.1!!!SO TOO THE TECH GUYS IN THIS TRHEAD DO YOU THINK MINE OR THE DYNOJET IS MORE ACCURATE? BERING IN MIND THAT MINE IS SEEING ALL EXHAUST GAS AND THE DYNOJET PROBE IS ONLY DOWN ONE OF THE CANS?????(PS THE DYNO GUY SAID MY GEUSS IS AS GOOD AS YOURS)?
 
#57 ·
Go to factory pro's web sight and see what he says about air fuel ratio and horse-power. The o2 sensor can be fooled, just a pin hole ex leak in front of sensor will make it read lean. By sticking it in one pipe and leaving the other muffler open you might have sucked a little air past the other muffler. Seems like all i ever read here is "dyno jet" thats ok but there may be other ideas out there that work as well or better. The air fuel ratio is just a small bit of info that you can get from ex analysis and it the part tha can fool you. With a 4 gas analyzer you can break the ex down into o2, co, hydrocarbons, and co2 it can then take these gases and come up with with lambda and or air fuel ratio. You might also go to www.bridgeanalyzers.com and see how they adjust fuel.
 
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