My job in Chicago went a lot more smoothly than planned so I had time to come home and put some stuff together....
Here is what I have for documentation so far. We never have looked for ultimate numbers in any of the three days we've worked on the dynos. Only confirming that we can do what we want with the fuel and ignition and that we were making the gains we thought we should with each change.
I've worked with two cars. First was an ITS prepped car that we spent some time with before swapping ECUs trying to optimize the stock setup as best we could. The numbers were not stellar but it's all it had. Playing with fuel pressure to lean out the top end we ran into a familiar situation. When trying to pull enough fuel you end up running very low pressure (~25 psi). This hurts atomization and overall performance.
After swapping ECUs the gains were best below and above peak power. This makes sense since when running the stock ECU we were tweaking the fuel pressure to optimize the peak number and thus compromising the rest of the rev range.
This particular session was our first day experimenting with the ECU. We found that the +/-25% fuel adjustment that we had built into the ECU was not enough to provide the desired a/f ratios above about 7000 rpm. The gains that were made there were done in the 12.8 - 13.0 range. We shot for 13.5 - 13.7 everywhere else. There was slightly more to be had at peak and beyond but the range of adjustment wouldn't allow it. After this day on the dyno we re-worked the ECU to allow +25/-30% adjustment to cover this area of the curve. Seems around -27% is a good jumping off area in this rev range.
All mod ECU runs were made with stock timing.
Stock ECU v. Mod ECU
Yes I resized this one chart and skewed it a bit. Not trying to bulge any curves. Just trying to get it sized decently and fairly sqaure.
Stock ECU v. Mod ECU
This past weekend we finally got a chance to try out the production version of the ECU. It just so happened that the car that was volunteered was a beautiful, almost bone stock 91 convertible. The car had only an RB header and was still breathing through the stock main cat. On the dyno the car just did not want to pull over 6000 rpm with the stock ECU. Power peaked at 122.8 whp @ 5750. With the mod ECU we were able to lean it out, make around 13 more peak hp, and broaden the power band by about 1000 rpm! Good gains. I'll admit not completely relavent to an ITS car but we were only trying to prove that we did indeed have control of fuel and ignition. I'm also posting the a/f logs from this session. The first log represents the stock ECU. The second what were achieved with the mod ECU. These are relavent to an ITS car. Again, stock timing was used.
Stock ECU Dyno
Mod ECU Dyno
Stock ECU v. Mod ECU
Stock ECU A/F Log
Mod ECU A/F Log
