Old school 5-knob SAFC: target AFRs?
 

Just got myself an AEM wideband and have picked up a 5-knob "older than time itself" SAFC and plan to do a a bit of very basic and mild fuel tuning on my 1991 S5 Tii FC. Don't have any major engine mods; in fact I've just got the emissions stuff removed, full intake & exhaust, stock & freshly cleaned injectors and a full tune-up. Have also done a complete rewire of the fuel pump to a straight relay and removed the variable resistor so I know it's going to be running rich.

The 5-knob SAFC just has 5 rpm levels at which to adjust the fuelling (800, 2400, 4000, 5600 and 7200rpm), and can adjust up to 30% either way of stock. Am probably going to do my tuning for 4000, 5600 and 7200 at WOT and will probably take a reading for 2400 at WOT and also when cruising too. Was wondering what I should be aiming for in terms of a little leaner but still safe AFRs. Am not going to be boosting much above 10psi (12psi would be an absolute and unlikely maximum).

Idle & WOT AFR thoughts would be appreciated :)

I have the exact same safc 5 nob on my 88. It was put in by the previous owner and I'm somewhat lost with it. Any clarification on the different settings on it would be great(tips for performance etc.)

safe AFRs at WOT on a turbo are between 10 and 12. a good cruising AFR is 13. These AFRs are conservative, but with a setup like that you don't want to get anywhere near the hairy edge of the fuel curve.