I searched and found one thread that discussed this topic but it was for turbo model and it didnt quite answer my question.

but I'm about to tune my car and I got a question...

I'm using an SAFCII and a AEM UEGO for the wideband, but what A/F ratio should I be looking to achive for optimal power? and its not like its easy as lean out the whole powerband or rich the powerband. what im trying to say is will different RPMs varey in lean/rich for optimal power?

oh BTW my setup is s4 NA with:

Atkins streetport
3mm apex seals
K&N intake cone filter
Centerforce clutch
Racing beat aluminum flywheel
12a tranny mod (shorter 1st, 2nd, 3rd gears)
Manual steering rack
Air conditioning removal
Air pump removal
ACV removal
Racing beat header/presilencer/cat-back
S4 clutch type LSD 4.10 ratio
SAFCII
AEM UEGO wideband
Walbro 255 fuel pump
5th/6th port/actuators & sleeves removed
Dual alternator pulley mod
Battery relocation
Custom dual calsonic Electric fans

 

Damn... Sound like you've got a pretty bad-*** N/A. However, I'm no "N/A tuner", so I can't help you.

Mid 13's?

 

who knows.

but depending on my tune, it should be 185-200whp

so somewhere in the 14's

 

I've got a lot of the mods you do, minus the 3mm apex seals and I have functioning 6 ports (w/ pineapple sleeves). Anyway, you can road tune an SAFC in like 30 minutes with a wideband. Do 2nd and 3rd gear pulls. Lean it out up top (5k or so), probably around 5-10%, and you may need to richen it up under about 4k slightly. Just play with it. The stock ECU does not smoothly hold one AFR under WOT, at least not on my car with no SAFC correction. It will go leaner and then richer some (if it's really bad, you may have ignition breakup), and then hit maybe high 11's by redline.

I wouldn't run it any leaner than 13:1, in my dyno experience it doesn't make any more power. Oh and you may have trouble breaking into the 180's on the dyno with stock s4 rotors and manifolds. I hit mid 170's, and that was with T2 housings and ported s4 manifold.

 

i've been debaiting doing the s4/s5 hybrid manifold and TB mod in the following weeks.

and high 11s seems be a bit rich

 

I have a complete S5 NA intake if your interested. Did you have to change the driveshaft when you put in the 1st gen tranny?

 

didn't have to.

you swap the tail shaft/shifter assembly off the FC 13b tranny onto the 12a transmission, bellhousing and starter bolts right up.

12a/13b N/A clutch/starter assemblys are the same.

 

For N/a Afr's Around 14 Should Be Good. Something About Ambient Pressure Being 14.7. I Read It Somewhere But Forgot Where

 

yes high 11's is rich. that's around what the car does stock. But don't go leaner than 13:1 under WOT b/c the car needs more fuel than that to make power, at least in my experiences on the dyno.

 

From what I've heard, engines in general make optimum power at just slightly richer than stoich (14.7?).

Now, what you'd need to do to keep an NA rotary in the safe zone, I'd don't know.

 

Haha, I meant tune the AFR's for mid 13's. Either way, I have no idea what I'm talking about.