What afr makes most power
- Thread starter nappinj12
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Bullitt995
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The answer is technically the stoich point for whatever fuel you're using. 14.7:1 is the usual for gasoline. Of course you would never run a motor at that. The usable answer is as lean as possible without detonation. It's different for every engine.
motor
race fuel
oxygenated race fuel
turbo
nitrous
1/4 mile
Land speed racing?
i am no expert on the matter but that is a very vague question you are asking without some specific details on your setup.
race fuel
oxygenated race fuel
turbo
nitrous
1/4 mile
Land speed racing?
i am no expert on the matter but that is a very vague question you are asking without some specific details on your setup.
peak power is richer than 14.7:1 for a gasoline burning engine. Stoich value gives the highest efficiency. Which doesn't mean best mileage it just means best burn. The last thing we worry about unless your talking emissions.
Like Smitha mentioned there are a ton of variables so this may be part of the reason you get many different answers.
I dig this up, it's a short article to give you some rough info: http://www.daytona-sensors.com/tech_tuning.html
Like Smitha mentioned there are a ton of variables so this may be part of the reason you get many different answers.
I dig this up, it's a short article to give you some rough info: http://www.daytona-sensors.com/tech_tuning.html
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hp will give you higher mph. you working on yoru launching skills will drop ET.
bobber
Registered
Tuneing [ fine tuneing ] is the key,,and you also have to factor in gear ratio,,what ever HP you have,,there are different gears for each HP,,......ie; too low of a gear,,youll do fine leaveing the tree , but you'll run out of motor near the end of the 1/4.
too high of a gear,,and its the opposite,,,terrible line leave,,,but you have a good upper 1/4 power wave,,,,,,I would start with getting a fine tune done by someone who knows what their doing,,,,remember,,HP is great, but in my opinion,its useless .if its hacky or all alone,, ,but you want a smooth consistant curve,,,Ive seen big HP engines lose to a lesser HP vehicle due to the HP and gear compataibility and also weight distribution,,,Fine tune first,,,get that out of the way,,then work your way back,,the gears for the busa's that ive seen are really reasonable priced, and get a good tire that hooks up,,and as communta stated,,work on leaveing the tree,,,that takes time,you gotta know your bike,,,over time,,I believe you'll get it,,,,,,get the tuneing done first to see what your working with,,best wishes
too high of a gear,,and its the opposite,,,terrible line leave,,,but you have a good upper 1/4 power wave,,,,,,I would start with getting a fine tune done by someone who knows what their doing,,,,remember,,HP is great, but in my opinion,its useless .if its hacky or all alone,, ,but you want a smooth consistant curve,,,Ive seen big HP engines lose to a lesser HP vehicle due to the HP and gear compataibility and also weight distribution,,,Fine tune first,,,get that out of the way,,then work your way back,,the gears for the busa's that ive seen are really reasonable priced, and get a good tire that hooks up,,and as communta stated,,work on leaveing the tree,,,that takes time,you gotta know your bike,,,over time,,I believe you'll get it,,,,,,get the tuneing done first to see what your working with,,best wishes
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Draco1340
Registered
The simple answer is somewere between 13.2 and 13.5 for a stock motor with pump gas and stock ignition advance.
The more complex answer is that there is huge variability in O2 sensors, gasoline BTU content, and air density on any given day, so what you tune for one day might be quite different later that week. For example, I have seen .2 difference from one O2 sensor to another. I have seen different pump gas make a .2 difference just based on different alchohol contents. Remember most pump blends run between 2% and 10%+ resulting in as much as 4% loss in BTUs. The refineries change the blend every spring and late fall every year, and that will change the A/F by .1 or more. Summer blend has higher average molecular density w/ less aromatics. Winter blend has more aromatics for easier starting.
And of course the weather changes and effects your A/F. In New Hampshire the air density altitude can range from -500 ft to 2800 ft and that can swing your A/F by .2 or more. Anyone who thinks that the bike electronics compensates for all that is kidding themselves. So, even if you had the "perfect tune" its only for that day. Most tuners try to shoot for something conservative, knowing that these types of changes typically occur. If you really need the very most out of a tune, you tune on the edge of lean with a datalogger for that days weather and fuel.
The more complex answer is that there is huge variability in O2 sensors, gasoline BTU content, and air density on any given day, so what you tune for one day might be quite different later that week. For example, I have seen .2 difference from one O2 sensor to another. I have seen different pump gas make a .2 difference just based on different alchohol contents. Remember most pump blends run between 2% and 10%+ resulting in as much as 4% loss in BTUs. The refineries change the blend every spring and late fall every year, and that will change the A/F by .1 or more. Summer blend has higher average molecular density w/ less aromatics. Winter blend has more aromatics for easier starting.
And of course the weather changes and effects your A/F. In New Hampshire the air density altitude can range from -500 ft to 2800 ft and that can swing your A/F by .2 or more. Anyone who thinks that the bike electronics compensates for all that is kidding themselves. So, even if you had the "perfect tune" its only for that day. Most tuners try to shoot for something conservative, knowing that these types of changes typically occur. If you really need the very most out of a tune, you tune on the edge of lean with a datalogger for that days weather and fuel.
Best hp afr 12.8:1 Best torque afr 13.2:1 Boosted 11.5:1 to 12.0:1. This is the basic tuning guide. Some Engines like a little more or less fuel due to many reasons... Cams, heads, pistons, turbo, supercnarger, and fuel used! I am running 13.1:1 at WOT at lower TPS position settings for slightly better response on my stock bolt on busa with 12.8:1 at higher TPS position settings. Leaner is meaner but can causes melt down of the pistons and burns valves. Richer is safer... a little less power and on boosted applications keeps things cooler!
Bullitt995
Registered
Running on the dyno and the track/street are two completely different animals for A/F readings. Find a tuner that knows how to use one to perfect the other...
Does no one used loaded dynos on bikes?
r1d3on3
Registered
basically your opening a can 'o worms. im opening the same can. read a 
load of books, online stuff, and ask lots of questions. When it comes down to it, the safe and best route to go is take it to a tuner who knows his stuff and get the bike tuned, or dig in and go the trial and error route.
load of books, online stuff, and ask lots of questions. When it comes down to it, the safe and best route to go is take it to a tuner who knows his stuff and get the bike tuned, or dig in and go the trial and error route.
On a diagonal line from 1250rpm/5%throttle down to 9750rpm/100%throttle I will pass through the following Target AFRs:-
1250/5 13.4
3500/15 13.3
4500/20 13.2
6750/60 13.1
8000/80 13.0
8500/80 12.9
8750/100 12.8
9000/100 12.7
9750/100 12.6
Gen2, normally aspirated, no nitro, shop gas, no ECU flash. Fooling the ECU with drivetrain cog changes. Fastest top speed for a standing start mile, 194.846mph. 1st goal is 200. So, so close!!!
1250/5 13.4
3500/15 13.3
4500/20 13.2
6750/60 13.1
8000/80 13.0
8500/80 12.9
8750/100 12.8
9000/100 12.7
9750/100 12.6
Gen2, normally aspirated, no nitro, shop gas, no ECU flash. Fooling the ECU with drivetrain cog changes. Fastest top speed for a standing start mile, 194.846mph. 1st goal is 200. So, so close!!!
RedBull
Registered
What's makes the hayabusa so much heavier? | Gen 2 Busa Information
Ok so I am looking around online to look at weight specs (unfortunately there really isn't a thing I have come across) to see why the hayabusa is so much heavier than say the 1k's. I know the head is bigger but I would find it hard to believe that a slightly larger engine would account for the...
Mr Brown
Registered
Passing through target AFR? Fooling the ECU through cog changes? What do those statements mean?
And I doubt you're getting to 200 in a standing mile on a stock motor.
Mythos
Registered
@Mr Brown I think MarcW is saying he is avoiding the top speed limiter by changing sprocket gearing?
Picture a grid with idle speed through peak rpm listed vertically on the LH side, throttle position from 0% to 100% arranged horizontally across the top. The grid forms a bunch of boxes or cells. 'Passing through target AFRs' means at X throttle position and Y rpm, the AFR number the fuel map is supposed to achieve is entered in that cell. Most maps have many different AFRs to optimize each possible combination of TP and rpm. You've seen a map fuel table before. It's the various corrections required/ TP and rpm to achieve the AFR you want (target AFR) for that combination of TP and rpm. An AFR table is the just AFR you want to achieve for each combination of TP and rpm. Marc's telling us what AFR his engine is using as he accellertes to top speed.
@MarcW that is very odd that you start at only 5% throttle and rev past redline and then open the throttle progressively wider only to rev to 9750 rpm...and you're doing almost 200mph at 9750? That must be some sprocket gearing you are working with and you must be out on the salt flats to have enough distance. It seems counterintuitive that you're using richer fueling up top where I'd think you want the most hp. Is this throttle technique and AFR table to reduce chances of engine failure at high speed? Most of us just go WOT as soon as we can and hold it there until the bike won't go any faster. Why start slow if the objective is to go fast? Get as fast as you can early as possible and leave yourself more distance to hopefully touch another tenth of a mph faster before you have to shut it down.
I also have yet to hear of a stock busa doing 200 mph.
Picture a grid with idle speed through peak rpm listed vertically on the LH side, throttle position from 0% to 100% arranged horizontally across the top. The grid forms a bunch of boxes or cells. 'Passing through target AFRs' means at X throttle position and Y rpm, the AFR number the fuel map is supposed to achieve is entered in that cell. Most maps have many different AFRs to optimize each possible combination of TP and rpm. You've seen a map fuel table before. It's the various corrections required/ TP and rpm to achieve the AFR you want (target AFR) for that combination of TP and rpm. An AFR table is the just AFR you want to achieve for each combination of TP and rpm. Marc's telling us what AFR his engine is using as he accellertes to top speed.
@MarcW that is very odd that you start at only 5% throttle and rev past redline and then open the throttle progressively wider only to rev to 9750 rpm...and you're doing almost 200mph at 9750? That must be some sprocket gearing you are working with and you must be out on the salt flats to have enough distance. It seems counterintuitive that you're using richer fueling up top where I'd think you want the most hp. Is this throttle technique and AFR table to reduce chances of engine failure at high speed? Most of us just go WOT as soon as we can and hold it there until the bike won't go any faster. Why start slow if the objective is to go fast? Get as fast as you can early as possible and leave yourself more distance to hopefully touch another tenth of a mph faster before you have to shut it down.
I also have yet to hear of a stock busa doing 200 mph.
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