Also, aviation is for profit. I don’t believe in socializing the losses and privatizing the profits.
So you want society to pay those costs in air fares. You want to throw away a lot of the GA fleet, including a vast majority of the trainer aircraft in service. You'd see a lot of flight schools especially smaller ones just fold because their current aircraft is useless and unmarketable, so they have no capital with which to buy new ones. A lot of flight instructors would lose their jobs, and flight instructor certificates are the only ones issued under Part 61 that expire. With fewer people being trained as private pilots you'd have a much smaller pool of mostly richer young folks to pull from for commercial aviation, so the main effect of this will be flying will become a rich son's way to demand more money from society.
The IO-390 is a derivative of the IO-360, which itself dates back to the 1950's. Funnily enough it's rated for a similar horsepower range to the O-360, but with 30 more cubic inches, basically having the same bore and stroke as the IO-580 but with 4 cylinders rather than 6. I wonder why they bothered.
You get to cherry pick an example, I get to cherry pick an example. The Rotax 915 was type certified a few years ago, it runs on premium automotive gasoline, features electronic capacitor discharge ignition, electronic fuel injection, turbocharged induction, dry sump lubrication, and a host of other features. It makes 141 horsepower, fairly close to the Continental O-300 that pulled early model Skyhawks. They just recently announced a 916 version that makes 160 horsepower, which is the same rating as early Lycoming powered Skyhawks. And they'll make their rated horsepower up to 15,000 feet. Couple that with a constant speed propeller and you've got a hell of a power plant for a trainer in both performance and efficiency, for both climbs and cruise.
Instead, the aviation community continues to drag its feet.
In 2004 the Light Sport rule was adopted, which put thousands of brand new lead-free GA trainers in the air, replacing an aging fleet of Cessna 152s and the like. It's been such a success that there's an initiative underway (MOSAIC) right now to expand the scope of Special Airworthiness Certificates to include significantly larger and higher performance aircraft, which stands an excellent chance of modernizing the GA fleet, making it much more practical to market new airframes and powerplants to flight schools and other GA operations. Part of the proposal is to remove engine-specific language from the rule to allow for electric propulsion.
The EAGLE initiative seeks to find a lead free substitute for 100LL by the end of the decade.
But you keep going off.