Originally Posted by
Sunfish
Ultralights:
The Rotax 912 iS (electronic fuel injection) does all this ....to replicate exactly what can be achieved by running lean of peak in a conventional Lycoming or Continental fitted with an engine analyser and GAMI precision injectors.
Overhead cams/four valves/adjustable timing, etc. is not warranted on an engine spinning most of its life at 2500 rpm and 75% power. All that stuff does is increase parts count, complexity, weight and probability of failure.
I am currently deep into setting up a 912 iS and the wiring is quite complex. For example, you need seven switches to control the engine plus master switch if you follow the Rotax wiring recommendations. *
* ECU A & B, Pumps 1 & 2, Start Power tie, Start and emergency battery mode.
exactly, its the reason the rotax is so much more fuel efficient compared to similar power outputs of its continental counterparts. but most GA aircraft run large capacity slow turning old tech carby engines, so their specific efficiency would be on the lower end of the 12 to 30% efficient scale.