How lean is lean?

[quicksilver7]

Hey guys, recently I was comparing a few dyno charts and one of them had an AFR of 13.5 low end around 2k to 3k rpm. I'm a noob but how lean is too lean? And how far can we go? Thank you!

 

[^pomen_GTR^]

i would say like this:

http://en.wikipedia.org/wiki/File:Ideal-stoichiometry.jpg

 

[quicksilver7]

Oh, so theoretically max power is made at AFR 12.6? I'm confused, some tuning articles that I've read mention that more power can be made since factory tuning is rich..

 

[^pomen_GTR^]

Oh, so theoretically max power is made at AFR 12.6? I'm confused, some tuning articles that I've read mention that more power can be made since factory tuning is rich..

that depend on which factory tuning...i suspect saying that was applicable for american cars with carbies...


well like example of newer generation proton (campro+siemens ecu) mostlikely the tuning was on the very edge of lean...i've read somebody wrote that he dynoed a stock campro car with 16:1 afr....

most boosted ride would opt for richer 13:1 afr at WOT in order to gain highest power and keeping the engine part such as piston and turbine cool enough..(too lean could result catastrophic piston/valve/turbo failure)

if daily tuned ride i would say 14:7 afr was among the best and safer choice...which balance the fc and temperature....

 

[bo093]

if daily tuned ride i would say 14:7 afr was among the best and safer choice...which balance the fc and temperature....

Not just balance FC & temperature, but you are burning nearly all the fuel.
Therefore, not wasting fuel to be unburned.
Even though we have catalytic converter to burn unburned fuel.

 

[D7zul]

Not just balance FC & temperature, but you are burning nearly all the fuel.
Therefore, not wasting fuel to be unburned.
Even though we have catalytic converter to burn unburned fuel.

cat con only convert harmful gasses to environmental-friendly gasses

 

[Dayline668]

Well in charged engine, u need 10-11 to compensate knock, in Malaysia fuel quality is so bad. 13 will definitely knock like hell n timing will need to be super low(this all depend on boost, compression, ron used). 14.7 is the ideal afr, but cruise can go for 15.7 to save some fuel.

For N/A 12.5 makes the best balance of power n torque, idle 14.7, cruise 15.7.

 

[spoon civic]

Well in charged engine, u need 10-11 to compensate knock, in Malaysia fuel quality is so bad. 13 will definitely knock like hell n timing will need to be super low(this all depend on boost, compression, ron used). 14.7 is the ideal afr, but cruise can go for 15.7 to save some fuel.

For N/A 12.5 makes the best balance of power n torque, idle 14.7, cruise 15.7.

gud info bro........................

 

[Izso]

Also, factory tune is rich for a reason. If they set it 'just right', then sometimes at higher revs or at certain conditions you'll run lean or very lean. Lean is bad. Better to waste some fuel than to have your engine cook itself.

 

[YeS_No]

Hye, i just wanna share some experiment & little info to all zth forumer..I've been using Wideband for a while, its brand Innovate and have tested to my car and other's is my friends car which is Honda FD (Mine) / Swift (Mine)/ Inspira / Saga FLX / Satria 4g91 Carbie in standard stock Factory, the result is..

Honda FD - Partial Open Throttle 14.7, Wide Open Throttle 11.5
Swift - POT 14.7 , WOT 11.5
Inspira - POT 14.7 , WOT 11.5
Saga FLX - POT 14.7, WOT 12.3
Satria 4g91 Carbie - POT 12.5, WOT 11

The conclusion is Factory Setting would be around 11~11.5 AFR and its rich condition, with ecu management such piggyback / reflash / Stand alone will trim WOT until 12.5~12.8 for N.A and 11~11.5 for TC or SC. I was very impressed because wideband reading for saga 1.3 FLX already nice and suit for best torque. For carberator fuel system it seems a little wasteful at cruising /low rpm since the reading much higher than other new injection car. Thats the benefit of injection system since its control by ECU management. Just for sharing :rolleyes:

Here are some schedule thats i always refer for self tuning...

 

[quicksilver7]

Good stuff guys!

 

[bo093]

cat con only convert harmful gasses to environmental-friendly gasses

Sorry
I think I fall asleep during class.

Those charts for RON95?
Different RON still the same right?
If never ask, never know right? HEHEHE

 

[D7zul]

my levin smells rich. mayb i should invest on a piggyback..