I found these diagrams. I thought you would be interested.

This one discribes how engine power and fuel consumption (economy) differs from air-fuel ratio.

so we can see, that max power is with 13:1 AFR and max fuel economy is with 17:1 AFR.

This one shows how AFR influence on CO, CH, NOx in exhaust gases.

 

hmmm, very interesting. I thought that 14.7 was best for performance...

 

that's why Hyundai runs a bit rich, performance wise.

14.7 is best for comprimise between power,fuel consumption and pollution.

 

Very good D..interesting find

 

Yep... I've got it down to 13:1 in my GSX from 3500RPM on... getting that darn low throttle wear I want is a pain in the butt... I can't richen it down from 15:1... aggrivates me.

Good find for those who didn't know, and refreshed my memory about the best A/F for fuel economy. If gas ever gets to be $20 a gallon, I'll know what to program my AFC to. lol.gif

 

14.7:1 isn't best for performance, or economy. It is simply the mythical point at which all gasoline will mix with all air and burn completely. I say "mythical" because it NEVER burns completely. There's always unburned hydrocarbons and air stuck in the tiny crevases.

That graph is just a guideline for ONE engine. Not ALL engine's make max power at 13.0 and max economy at 17.4 Each engine is different. Some engines achieve max fuel economy around 20:1 (called lean burn engines). Some engines need 10:1 to make max power (they are using the added fuel to cool the intake air charge)

Some Forced Induction setup make their max power at 13.5:1 some at 10:1. Some N/A engines will make max power 14:1 some at 12.5:1

In general, turbocharged/supercharged engines will make max power running richer than Normally Aspirated engines (usually the cooling of the additional fuel is need to make max power).

Each setup is different. Treat it as a guideline, not as gospel.

 

Thankyou Random... sometimes there are no absolutes

 

What influences our stock ECU to mix air and fuel? Is it only the oxygen sensor? Do you guys clean the sensor regularly?

(Assuming there is no SAFC)

 

MAF sensor is one of the main sensors that tells ECU how much fuel should be dumped, then o2 sensors take or add some more. Factors like temperature, throttle position, etc will influence the amount of fuel being dumped.

 

that is very interesting.... But we only can know about the a/f ratio with a Wideband or with a Dyno.

could be possible to change the A/F ratio that far with the SAFC?.