Skytouareg

Enjoyed all your articles on MAP, RPM and mixture. As you noted, current cockpits with EDMs measure LOP and ROP indirectly via EGT & CHTs. The best way to set air/fuel mixtures directly is thru a Lamda or Air/Fuel gauge which use a oxygen probe in the exhaust stack as have used on cars with EFI/ECUs for more than two decades. Unfortunately, the lead in 100LL quickly contaminates the oxygen sensor and another reason to get lead out of aviation fuels so this technology can be adapted to aircraft engines. I have the advantage of flying a experimental Super Legend with a low compression Continental Titan x-340 and can burn lead-free 93 octane MOGAS. So, minus the lead, can adapt a dual Lamda gauge with dual oxygen sensors, to monitor each of the twin custom tuned exhaust stacks. For take off and climbs use a best-power setting of 12.7:1. In cruise, make the rapid mixture pull to the lean-of-peak setting of 16:1. For peak output for best speed use 14.7/1. I still use my EDM for all the other information it provides for monitoring and trouble shooting but the Lamda gauge sure cuts down the tweaking of the mixture knob. The Bosch oxygen sensors are more resilient to lead contamination and as long as you keep the engine LOP this contamination is minimized. Addition of 4 oz of Marvel Mystery Oil to 10 gallons of 100LL helps reduce the contamination for longer sensor life when forced to buy 100LL on cross countries.