I have a GSL-SE stockport 13B 6-port with Weber IDA (Racing beat recommended jettings) and I just installed a AEM wideband to the rear exhaust pipe 18 inches from the exhaust port. I want to know what is the recommended AFR for a NA rotary?

 

I would assume the same Air Fuel Ratio for normal gasoline combustion engines?

 

i think its safe to be right about 13

 

The Stoichiometric Air Fuel Ratio is 14.7 parts air to 1 part gasoline or 14.7/1

That's the ideal mixture for combustion... at least that's what they teach us in school.

 

You usually want richer at high rpm... They need to teach you more at school.

 

*shrugs* Its what they base "Lambda" off of and what your WideBand (or Air Fuel Ratio as it's also known as) sensor is looking for, it is trying to keep your air fuel mixture at that 1 Lambda or 14.7/1, it just does it at a tighter range than a normal O2 sensor.

That's what the ideal mixture for efficient combustion is supposed to be, plastered all over the text books and wikis and all that junk...

 

It is ideal, but there are more variables at work in the real car engine. What 14.7 is, is the mixture required for complete combustion. Less fuel and you'll have an incomplete event, more and you'll have fuel leftover (running rich).

When dealing with real engine applications and the fact that it never works how it's supposed to, you usually run richer to combat preignition, among other factors.

^That is exacerbated with forced induction.

As for the OP question. I read some where that while stoich was 14.7, peak HP occurs in the low 13's and peak mpg in the mid 16's.

I'm not sure because I'm a turbo *****, but I would shoot for low 13's, hi 12's.

At idle and low load you can get away with mid 14's easy, though I know that may be hard to tune with carby.

 

When I had my car dyno'd we had a tester in the exhaust at the rear of the car (not as acurate) the car ran best at 13.5