Originally Posted by
Sunfish
The Rotax injected engine has Two of everything; ECU, MAP sensors, temperature sensors, airbox temp and pressure, knock sensor fuel pumps, eight injectors and plugs, coil packs and of course Two permanent magnet alternators with automatic fail over from one to the other and space for a belt driven alternator as well.
There is both an ECU box and a "fuse box". You require seven switches to control the beast (ECU A & B, alternator tie (for starting), start, fuel pumps 1 & 2 and emergency battery mode. The use of a key switch is not advisable because they can be unreliable, I am using only MS 35059. Then of course you will need an EFIS or a $3000 engine display unit because all data is provided by an automotive CAN bus protocol. The supplied wiring loom has plugs on it that must not be inserted/removed from the ECU more than 20 times or you need to replace the wiring loom (plug connect/disconnect must be entered in the engine log).
But wait, there is more, each cylinder has an EGT probe and. at less than 97% power, the engine runs in "ECO" mode which probably means its running LOP (rotax doesn't say) and you adjust required power by setting fuel flow.
Since the engine will immediately stop if it loses fuel pressure even for a fraction of a second, you need a header tank capable of flowing 70 ltrs per minute with no bubbles, a seven micron high pressure fuel filter and of course the aforesaid Two alternators and two fuel pumps.
the benefits of the technology are greater fuel economy and a smoother engine for a few extra kg of electronics.
So yeah, I don't understand why Lycoming and Continental aren't falling over themselves to install cheap, simple automotive EFI instead of those complex, inefficient and unreliable carburettors and WWII era injection... complete with mixture control..
Sunny, Point one highlighted above......Power set by fuel flow, you can call that the BMEP drop from the big old radials or you can call it Best BSFC or you can call it "Appropriately LOP". I think you nailed it
Point two.....hmmmm Lycoming have tried. But the sensors are the issue. The dated complicated and hard to use red knob replaces all that. As you have eloquently stated above, all you need instead is a well balanced F/A ratio and a mixture knob and some very simple knowledge that results in the Big Mixture Pull.