air fuel ratio

[srdub-t]

im prolly not searching right because i cant really find anything but i gotta redtop sr and on my wideband im hitting 10.0 afr all the way up to like fivek rpm then it starts to creep up to like 11.2 and i was just wondering if 10.0 is way to rich or is it not that bad?

[DrifterProdigy85]

10.0 is very rich. Majority stock setup SR's run this way though. Get an SAFCII and adjust the AFR to around 11.6 from full boost to redline.

[IanS]

rich is safe

[BEST1TUNING.COM]

SR's come pretty detuned. You will see lesser performance at that AFR as well as less MPG fuel economy.

Just remember that as you are leaning out the AFR with the AFC, you are also increasing timing. Performance wise SR's dont like very much timing in certain areas. Jumping from a 10 AFR to a high 11-12 is going to bump your timing about 3 degrees on an already less optimal timing value.

Also ignition wise the car is tuned for 10 AFR and Im not talking reliability, Im talking performance. As you are leaning out the AFR you are also increasing the burn speed of the mixture due to a leaner burn which will give the effect of greater ign timing as the burn will complete at an earlier crankangle. These are two seperate ways the tune will suffer from an AFC.

So yes you can lean yourself out but in the end you may not benefit from it. AFR is just a tiny aspect of tuning. You have to look at the whole picture to properly tune an engine and actually get positive results beyond AFR readings.

[turbomrdeuce]

rich is safe

not always thats how i ****ed up all my crank bearings up. Too much fuel=losing viscosity in oil=BOOM

[TchouikoS13]

so in that case, best1tuning.com, what is the best way to go about this?

As in the best way to lean it out properly

[BEST1TUNING.COM]

The best way is retuning the car for best fuel efficiency and performance through a form of management that gives you control of both fuel and ign timing. I think he will be more satisfied with the results doing it that way.

[oki_bum]

So what is a good ratio for then for normal driving? On the highway my a/f gauge is reading 13.2-13.9. Its the same for city too.

[BEST1TUNING.COM]

light cruizing can be into the low 15's and city part throttle should be in the 14's. you shouldnt see 13 unless you step on it.

[turbomrdeuce]

u dont want to be in the 13s if you step on it.... why do you want to run lean??? for your sr best a/f on pump should be 11.8 on race gas the most 12.5 depending on egts. This is regarding to "stepping on it not on cruise"

[BEST1TUNING.COM]

I was refering to when you first get into the throttle. 13 and then down into the low 12's and high 11's.

[turbomrdeuce]

oh ok, well i was just trying to be a little more specific so he doesnt go off and try to tweak his car by himself and blowing it up

[DrifterProdigy85]

14.7 while cruising under vacuum, should gradually richen while more gas and boost is aplied, WOT under boost should be around 11.6-11.8.

[hpmachine]

I've read several different things regarding a/f ratios but it seems that generally you want about 15:1 at idle (stoich is 14.7:1) and then slowly richen the mix as you get closer to boost. Hit about 13.5:1 by the time you are at 0 hg/psi and then be around 11.5-12:1 at WOT. I'm actually having a lot of trouble with mine right now under deceleration and light cruising. It's running way rich- like 12:1 at 8% throttle and 2400 rpm. I've got a jwt ecu and an s-afc.

[IanS]

not always thats how i ****ed up all my crank bearings up. Too much fuel=losing viscosity in oil=BOOM

I didnt say super rich is safe, I meant that running on the rich spectrum of things is much safer than running on the lean side, Ive seen a few too many cars come into the shop with holes in pistons and melted spark plugs from amatuers trying to milk every last HP out of thier engines, I wont run leaner than 11:1 at 17 psi in my Legacy(USDM STI motor), I could tune it leaner(Link standalone), but its not a dyno queen and I dont feel the need to have huge numbers or beat every honda civic I see, Ill keep it rich cause I want it to be reliable. Lots of people want to make more power, but too many of them think they can do it by just turning up the boost, or leaning out the fuel curve, and thats fine, but you have to know when enough is enough.

sorry about venting, I just finished trying to explain to some dumb 17 year old kid that the reason his 02 WRX wont run right is because you cant just stick STI injectors in and expect the stock ecu to componsate. His reaction to this was "well what if I turn the boost up? wont the extra air equal things out" It wouldnt be so bad but the same thing happend last week, but on a 2G DSMI guess Im just mad at the world today

the moral of the story is, if your gonna do somthing, do your research, do it right, and if you dont understand, get help

wow I have wandered so far off topic its not even funny, must be time for bed

[BEST1TUNING.COM]

hpmachine has it right on the money. That is exactly what you want. Oh and by the way hpmachine...if you want me to fix that JWT stuff I have definatly done a few. I really dont see HOW people are paying so much for these....

[turbomrdeuce]

i agree with you best1tuning and you hptuning even though for me 12.1 on pump is a little sketchy but it all depends on your mods and how much boost i guess... But hptuning tune your low throttle settings on your safc that should fix your problem some what but lo throttle tuning takes alot longer than hi throttle

[turbomrdeuce]

I didnt say super rich is safe, I meant that running on the rich spectrum of things is much safer than running on the lean side, Ive seen a few too many cars come into the shop with holes in pistons and melted spark plugs from amatuers trying to milk every last HP out of thier engines, I wont run leaner than 11:1 at 17 psi in my Legacy(USDM STI motor), I could tune it leaner(Link standalone), but its not a dyno queen and I dont feel the need to have huge numbers or beat every honda civic I see, Ill keep it rich cause I want it to be reliable. Lots of people want to make more power, but too many of them think they can do it by just turning up the boost, or leaning out the fuel curve, and thats fine, but you have to know when enough is enough.

sorry about venting, I just finished trying to explain to some dumb 17 year old kid that the reason his 02 WRX wont run right is because you cant just stick STI injectors in and expect the stock ecu to componsate. His reaction to this was "well what if I turn the boost up? wont the extra air equal things out" It wouldnt be so bad but the same thing happend last week, but on a 2G DSMI guess Im just mad at the world today

the moral of the story is, if your gonna do somthing, do your research, do it right, and if you dont understand, get help

wow I have wandered so far off topic its not even funny, must be time for bed

i couldnt agree with you more on the leaning out and idiots blah blah (not trying to insult btw) theres this shop around my area that build frankesteing hondas and boost them and then lean them out to abour 13.2 a/f all the way to redline just to get as much power as they can

[DrifterProdigy85]

You have to tune AFR based off Throttle % and Boost. You dont need to be at 11.5 AFR if your only at 25% Throttle and building a few psi. It should richen gradual as you apply more throttle which also builds boost. Mine at like 20% may build around 2psi around 2500-3000rpm and my AFR is like 14.0. As i apply more throttle and the revs climb while boost is being built, it will gradually become richer and richer till you reach 100% throttle and full boost which is generally near 11.6 AFR. Tuning is done in small steps and not just going from 14.7 under vacuum to 11.5 at boost.
Modified by DrifterProdigy85 at 10:17 PM 5/9/2007

[turbomrdeuce]

im sorry i believe we were talking about full throttle a/f