R33 Safc Tunes

[Muzzarat]

hi all, i have an r33 rb25det with exhaust, bigger intercooler, blitz boost controller, splitfire coilpacks, and adding a safc within the next 2 days or so to try to stop it from running to rich.

does anybody no the air fuel ratio for a 25 running 10 psi?

[mad082]

as for what it is currently running now i'd say probably around 10.5:1 at high rpm. tuned you want it around 12:1, however when tuning with a safc you also end up altering the timing so you may not get it that lean. you might only get it to about 11.5:1 before it starts to ping. either way, a tuner should be able to sort it out for you since they will have a wideband o2 sensor to measure it (don't try and tune it yourself without one).

[jjman]

i wasnt aware the safc altered timing. How does it do that?

[Tangles]

hence why you also use the apexi sitc, to be in control of the timing change(s)

safc + sitc with z32 afm = good combo

ran this myself, however changed out for AEM f/ic-8 (like greddy emanage ultimate) when upgraded to GT30 turbo

[Muzzarat]

haha jjust out of curiosity, how does a sitc work, never knew what they were until i googled it just know?

[mad082]

i wasnt aware the safc altered timing. How does it do that?

you are altering the AFM signal. generally the AFM voltage is used as the load scale and the RPM as the other scale. if you alter the AFM voltage you then alter the load scale and since the timing varies depending on the load, you end up altering the timing. most people don't realise this so if they do it themselves they may get the AFR's right but have the car pinging because they weren't paying attention to it.

[jjman]

ah yes. that makes some sense.

Gotcha. good description.

you are altering the AFM signal. generally the AFM voltage is used as the load scale and the RPM as the other scale. if you alter the AFM voltage you then alter the load scale and since the timing varies depending on the load, you end up altering the timing. most people don't realise this so if they do it themselves they may get the AFR's right but have the car pinging because they weren't paying attention to it.