Tuning Queries

[No Crust Racing]

Afternoon gents, some clarification on some tuning concepts would be greatly appreciated and NS is giving me nothing at this point, allow me to elaborate.

CA18DET Currently has

-Stock fuel system, injectors, pump etc (I realise I need to upgrade these to go further, see below).

- T25G, 13psi

- Basic supporting mods, oil cooler, fmic etc

- Used primarily for track duties

- SAFC II Adding fuel from boost transition point onwards, around 16-17%

- AEM Wideband installed

- Standard ECU (going of previous receipts it said "tuned" when the previous turbo was repaired, only thing I note is it's running 7 deg base timing instead of 10 - checked with timing light after noting CAS was clocked). Last dyno sheet was approx 164rwkw at around 12:1 afr.

Now I'm in the process of fitting a GT2560/S15 BB T28 which will obviously flow a lot more air at 14 or so psi than the T25G and will fit some GT-R injectors and possibly a bigger AFM as I expect the standard items to be approaching the limits.

Am I right in my reading that adding fuel in the SAFC retards timing and removing it advances timing? So at the moment my timing will be less than stock as the SAFC is telling the ECU that it's got higher load than it really does to get more fuel, in turn retarding timing? Plus it's got retarded base timing - putting it back to standard 10 deg seemed to make it knock (SAFC knock reading using factory sensor).

If that's the case, putting in larger injectors/fuel pump will require me to add less fuel to get the right AFRs so timing will be closer to "normal" or do I have it backwards? With timing close to factory, will that be my biggest risk of knock or will increased cylinder pressures from more boost be a more likely culprit?

I realise I can go Nistune etc and have full control over timing, I'm only interested in what will occur with the SAFC at this point, as an aside SAFC II has the agbility to transalte between RB25/Z32 etc AFM to CA ecu, manual shows the values required.

Cheers