Whats a good A/F Ratio

[gtpornstar]

Started playing around with a wideband ... was hoping someone else has had some experience with tuning.

I know 14.7 is a perfect burn
Leanest people would use is low 13:1
Safest tune around 12:1
Rich tune 11.5:1

But what about below that ... 10.0-10.5 ?
When do you start to get bore wash ?
I need to adjust my AFR but all this time been running low 10's so thinking what effect this would have had on the motor.

[Ako]

Thats fine - its mega rich and you have a lot of power to be found, but not "unsafe" in any way. You won't have done any damage at all - some mitsi's run this rich out of the box at some points on their mapping, especially when tinkered with a little.

[crnkin]

what engine, what power, what comp ratio, and what induction? makes a huge difference to what is good and what is bad

[Donor]

all this time been running low 10's

Thats pretty quick man!, If i was getting those sorta times I wouldnt be touchin Shit hehe

[gtpornstar]

Thats pretty quick man!, If i was getting those sorta times I wouldnt be touchin sh*t hehe

haha I wish
Maybe in my supra and a few months time ....

what engine, what power, what comp ratio, and what induction? makes a huge difference to what is good and what is bad

1500 motor, around 110Kw at the treads, running high compression (190psi per cylinder) + 12psi boost, no knock ... let me know what you think.

Thats fine - its mega rich and you have a lot of power to be found, but not "unsafe" in any way. You won't have done any damage at all - some mitsi's run this rich out of the box at some points on their mapping, especially when tinkered with a little.

Thanks man, if anything this should reduce chances of detonation as the extra fuel should cool right ? Thinking of leaning to low 11's

[IH8TEC]

fortec performance told me about 11.5 is good for a turbo car when i had my car on the dyno there for a bit of tuning

[crnkin]

lets start then, megasquirt suggests

quote "You are aiming to achieve 11.0-12.5:1 air/fuel ratios at full boost, and 15-17:1 under light loads for a turbocharged engine."

does your engine have oil squirters? this also allows a higher afr, as less gas is needed for cooling of the pistons

Also, at this "relatively" low boost, id tend for the upper end. 13.0:1 can be done, but i wouldnt like to drive it to work and back, aim for 12:1 would be good.

hope this helps

[gtpornstar]

Thanks guys
No oil squirters.
Yes egt's must be high with high compression and almost 1 bar boost.

[Si]

sucky sucky AFR

[deepsyot]

what engine, what power, what comp ratio, and what induction? makes a huge difference to what is good and what is bad

That's about the answer you can expect. There are so many variables when looking at your AFR's. I can run 12.5 at 1 bar boost in road car but in race car running higher compression have to run 11.8 at 0.7bar.
Look at EGT's and knock to determine what you can run. There is no right answer so you'll have to find out for yourself.

[QikStarlie]

shams: im running on the low side of 12.5afr on my 5e. 15psi and crappy 95 octane. lower compression tho. are you using a 5efe or 5efhe? timing? i'd be going for high 11's

[BBBrad]

What kind of wide band setup did you get?

[Akane]

the higher your afr is, the more extreme you are.

[Silent Knight]

the higher your *insert anything here*, the more extreme you are.

^^^That is your answer to everything lately.

[Akane]

coz i'm FRIGGIN EXTREEEEEEEEMEEEEEE! >_<!

btw, my AFR is 12:1 @ max power.

Ofcourse, goes nicely with the BHG, tuner must've went "let's dial this to 15:1 coz Akane's car is extre......... OH SXXT!....... car's overheating! Should I fix it? nah, that'll make me a responsible tuner, what's next, Santa handing out toys on christmas day?"

[EVLGTZ]

Shams - u know my car. Well use to have AFR around 10:1 - 10.5:1

Cleaned up the tune and took a fair bit of fuel out back to around 11.8:1 and its feels like it accelerates much crisper and cleaner.

I think max power worked out about the same, maybe slight gains but thru the rev range it made a notable difference.

[gtpornstar]

Using a 5E motor with 4E head and reground 4E cams to 273 duration and 8mm lift I believe, dont feel it to be much different to the standard cams though on paper you can see a difference
Using a LM1.

Will drop lean it out to the high 11's.
thanks boys

[QikStarlie]

nice, you should probably give me those cams since they arent doing anything for ya

heres an oldish lm1 log of the 5e.

3rd gear. starts at 3000rpm. full boost around 4.5 sec i think. and 7 sec is rev limiter


12.2:1 spose to be all bad i hear...

[strx7]

Remember to tune in 4th, or doe it in 3rd and drag the brakes a bit, otherwise you dont get enough load.

every set up is different, Intake air temp also needs to be considered.

my 2JZGE surf is running 16-17:1 cruising on the open road, and 13.2-13.7 at WOT thru to 6500rpm. On pump gas i personally wouldn't go any leaner than 12:1 at anything above 10psi. If you have avgas then you can push the point a tad more.
10's are too rich for a piston engine i believe, more of a turbo'd rotary AFR.

[QikStarlie]

yeh find a nice long steep hill is the go. tuning in 4th on the road is a bit ruthless in a starlet, 200km/h+ (with the standard box).

i find the 5e falls on its ass going much leaner than 15:1 under cruise conditions