I am really hesitant to post this question, but lacking a mechanical dyno how do you approach tuning timing from generally scratch?
1. EJ257 shortblock w/ Crawford CP pistons & oem rings replaced, v7 Jap STi (non-ra) heads - avcs disabled for the time being, FP Green, UTEC, 02 WRX hacked injectors, fujitsubo 4-2-1 header.
2. I destroyed the ringlands on my original oem piston #4. The reason I bring this up is because I am suspicious that the timing values I used previous to rebuild were too high.
3. I am comfortable tuning my fuel. As a matter of fact, I bought my UTEC in OCT/NOV 02, new absolutely zero about tuning but tuned it to where my old 2.0 ran a 12.7 @ 104 back in APR 03. However, the extent of my timing tuning has been confined to pulling some around knock spots.
4. I've got a Perrin bigmaf I've yet to install. It's obvious, even untuned, that I am nearing the maf voltage limit (of my current setup) but wanted to have a solid baseline map before I put it on.
5. Lastly, I understand that the overall intent behind tuning timing is in finding Maximum Brake Torque. I believe that generally this is to be done before you touch fuel.
Mick tthe Ginge provided me with a good, solid basemap, however I'm having trouble tailoring it to my car. This is after I've dropped some timing (I know the timing is too low at this point.). Oh yeah, my scaling is set to 420/650.
Click here for very short, recent log - excel format
Here is a log I took at the dragstrip shortly before I broke that ringland back in JAN 04.
Click here - excel file
Caveat: I'm not a tuner. There is quite a bit I still need to learn. Any constructive criticism is welcome. If I've omitted anything, let me know.