IMO, the FAA and their standardization processes for fuels like G100UL (GAMI), UL102 (Swift) and 91/96UL (Hjelmco) is the bottleneck here. GAMI in particular appears to have a fuel ready to use (in lab/prototype quantities) and has flown test flights in normally aspirated and turbocharged applications. (Turbos live a harder life, have lower detonation margins and are generally a more difficult test case. Many normally aspirated engines would run fine on ethanol-free pump gas from the corner service station.)
I don't necessarily fault the individual FAA employees; they have every incentive to make GAMI, Swift et al jump through hoops to prove that their fuel is as safe and has as high detonation margins, even in worst case, high, hot and heavy departure conditions, as the proven over many decades 100LL fuel. It's a "heads I lose", "tails we push" set of incentives for them, so I don't blame them for being reluctant to move swiftly.
I feel bad burning 100LL in an engine (from Continental) perfectly capable of (and even happier) running on ethanol-free 87 octane pump gas. I'd happily buy clean mogas instead of low-lead, but it's virtually impossible to find and low-lead is available at the overwhelming majority of airports.
Yet another advantage for aviation diesels (like the Thielert, Delta Hawk, etc.), largely developed due to the military drone program. They can run on Jet-A/JP8/diesel, and getting clean diesel is a whole lot easier than clean gasoline.
I don't necessarily fault the individual FAA employees; they have every incentive to make GAMI, Swift et al jump through hoops to prove that their fuel is as safe and has as high detonation margins, even in worst case, high, hot and heavy departure conditions, as the proven over many decades 100LL fuel. It's a "heads I lose", "tails we push" set of incentives for them, so I don't blame them for being reluctant to move swiftly.
I feel bad burning 100LL in an engine (from Continental) perfectly capable of (and even happier) running on ethanol-free 87 octane pump gas. I'd happily buy clean mogas instead of low-lead, but it's virtually impossible to find and low-lead is available at the overwhelming majority of airports.