It seemed to take forever to wrap this engine upgrade up but its done now. The first start was amazing, fuel pump on, ecu power on, hit the starter and it burst to life in a few seconds. I quickly checked the BTDC notch with a timing light to confrm the 10 degrees I had set in the ecu was the real value it was reading and then got into playing with the mixture knob to get a smooth idle. Adjustment of the PSRU belt tracking followed and then verification of guages as it warmed up. The Air to Fuel ratio was not reading properly so I ignored it and played with the mixture adjust at a few power settings.
A bit more investigation on the A/F probe indicated that the standard unit I had installed had an effective range of 13.5 to 15. That range is of little use when tuning for power as I target for 12.5 A/F for max hp. A quick chat with Ross from SDS put me on the right track and I ordered a PLX wideband AF meter. This unit provides a range of 10 to 20 A/F readings with .1 A/F ratio accuracy. The sensor module has two analog outputs, 1 goes to the SDS controller and the other to an organic display module. Once installed I had a perfect indication of A/F ratio thruout the entire RPM range I use. One of the ECU contol parameters adjusted is the Fuel Number. This number is entered for every 250 rpm step from 500 rpm to 7000 rpm. You play with this number and fuel mixture adjust knob until you get a A/F ratio of 12.5 or so and a knob set at 12 oclock position which indicates zero mixture bias. Doing this task for the engine rpm range takes 30 minutes with the aircraft tied to a truck, prop on and engine under load. Its of no value to do this with the prop off.
This is a very quick summary of ECU setup, but she’s done and waiting for a chance to go flying and prove out the new engine. I also added 3 more degrees of pitch to the prop in anticipation of all the extra HP I will have available now.
These pictures were taken before final cleanup was done. I’ll try and update these next time I am at the airport. I redid the copper sensing line for coolant pressure and ran it in the wire loom that goes back to the firewall.
