Sorry Dan, not personal,

You are just representing a business.

In short, after throwing FUD after G100UL, denying they are voicing/ representing
a vendor, acknowledging they don’t know if a tsio520UB will be supported as is, actually hinting either minor or major mods will be required, they are told …, ignoring other variants like 550 TN, a new paradigm was created..safe envelope…

I can certainly see with joy, my engine, modified to either set max map at 23 inches or to modify the timing or the pistons so we produce less power to avoid detonation… yes making stuff up because we are only told…”we” manufacture the fuel but let third parties to figure out if it works….we don’t test it…

And leaving sarcasm behind, no, according to you, your fuel does not seem to be a viable option for my engine, at least not on paper, or I should say on screen, that is the only evidence we have. Because my command of the English language is far from good, in case it was not clear, by wanting options, I meant a fuel I can run my engine “as is”.

I will certainly give you credit and buy your fuel if it can be used in my engine. So far the things you are told you shared with us, don’t preclude such.

Btw admins, time to bill them as sponsors, they are not here to help settle LOP vs ROP or 100 dollar burger trip suggestions. at least they can contribute to keep BT running

The near future will be a large change in engine manufacturers going to Diesel/Jet-A only for GA aircraft. I don't think there is enough demand for 100LL or UL when we get to the nitty gritty of it.

I think flight schools will be flying aircraft that burn diesel to train future commercial pilots, but I'm unsure how it plays out for us recreational flyers who own older models.

To be clear, in my mind there is a difference between “viable” and “with no issues”. I expect there are going to be issues with any change in fuel. Some real, some that would have also happened with continued use of 100LL. If G100UL does cause widespread problems with well maintained tanks due to materials compatibility problems, that’s a pretty big deal. If it happens to a few select tanks that already had small leaks, that is a minor issue that should have been addressed anyway.

The important thing to keep in mind is that so far, the issues with G100UL are much smaller than those with the other two fuels, so if it is a least of three evils situation, that’s still better than taking the worst of three evils, or having no solution when the one TEL plant suddenly goes offline.

We have been hearing about these diesel engines being right around the corner for 30 years now. There would be a lot of benefits to standardize all aircraft on a single fuel (Jet A) but I am not holding my breath. There are good reasons they have struggled.

A concrete example.

If the engine in the DA50, would be certified in a B36TC, At least, ignoring physical installation hurdles CG etc it would be probably 180 pounds heavier … using web sources … so take w grain of salt

A solution that address 80% of the fleet that doesn't address the 20% of the fleet that burns the majority of the fuel is not a solution. Frankly, it's a distraction. A reduction in performance is not a solution. I'm curious of that 80% what % is currently supported under STC's to burn auto fuel as is..

It appears that only way to get to a reasonably priced fuel is by sacrificing something. Why? Chemical engineering. Lead is a near-magic octane booster. With that key ingredient out of the picture, we can only get so close to a 100% drop-in replacement. The question is which of the key metrics we choose to sacrifice... Cost? Octane? RVP? Material Compatibility? Shelf life/stability?

It isn't the engineer's fault (or the refiner/blender's fault) that a government bureaucracy established a requirement (no lead) that is incompatible with the laws of chemistry/physics and the intended use of the product.

Dan I appreciate your participation here and I assume you're here to learn as well as answer questions. There are a couple of very important isssues I believe you should give serious thought to WRT an unleaded gasoline for piston powered aircraft.

1) Any required modification that reduces performance is pretty much a non-starter. OTOH if you come up with a fuel that requires simple and inexpensive alterations that do NOT affect performance (e.g. horsepower, full power and cruise power BFSC) I think that would be acceptable to the market. Even a small performance change would require modifications to the operating handbooks for all affected aircraft and that would be a huge undertaking, especially considering that there are plenty of aircraft flying today whose manufacturers no longer exist.

2) Very few airports will ever be willing to offer multiple avgas types, it's simply not economical. It's not like the automotive world where retailers often provide two or more choices. Thus the only viable way for multiple unleaded fuels to exist in the marketplace is if they're completely fungible. You might think that pilots would simply choose to fuel at airports providing their favorite avgas but that's not plausible either for a number of reasons.

Both of these issues are pretty unique to aircraft fuel, primarily due to the heavily regulated nature of flying. If this fuel was for a boat, it would be a very minor annoyance if one's boat engine needed the timing retarded a few degrees even if that meant the power output dropped several percent. Boat operators who want to retain the original power output can utilize boutique fuels for the times when that's needed, and since boats are often fueled via portable tanks it's feasible to seek that out. Since there are no regulator hoops to thread it's much easier to comply with whatever changes are needed.

An important fact: a timing mod may, in itself, be a "minor modification" (I can do it in seconds); but once the timing has been changed, the aircraft is no longer a certificated aircraft fit and legal to fly - the performance data which define how the aircraft can operate are no longer valid.

A fuel which cannot be used in the high-compression, spark-ignition engines that represent the majority of aviation fuel sold and used is not a viable fuel.

If it’s chemically impossible to safely replace 100LL, then what’s needed is a domestic lead manufacturer and another 50 years to figure and phase it out.

G100UL, engine wise, does work today. On All engines.

Just saying, until demonstrated otherwise.

It's not clear that it works. So far, in extremely limited real-world application, there have been numerous issues.

And again, it is suspicious that a much larger company, with way more resources than GAMI, would develop a fuel that has limitations. There must be a reason that they have chosen to do so. The most obvious explanation is that GAMI's approach has flaws that the public hasn't discovered yet. Otherwise, the much larger company would have just bested GAMI.

Maybe nobody has discovered a way yet to create a fuel that has no flaws and that works for all engines. Seems like the most likely explanation.

Explain to me how the most obvious reason are flaws in their product. That's pure speculation.

It is pure speculation, yes. Instead of "flaw," you could also call it "tradeoff." There is some tradeoff that the much larger companies were unwilling to make, which results in their fuel not working for all engines. It's highly unlikely that they didn't know how to make a fuel that, just like GAMIs, works for all engines. They've intentionally not done that.

The obvious question is...why? I'd love to get an answer to that.

[NOTE: I just realized this is in an intro thread - perhaps the discussion should get moved to another forum specific to the fuel]

Here are a few resources that I would recommend reading, which might shed some light on the discussion here. The STC vs PAFI program have some differences.

FAA Unleaded Fuels
flyeagle.org has additional info

From there you will find the FAA's policy statement about the fleet authorization process being alluded to for a candidate fuel.

The FAA has some valuable lessons learned documents from the previous PAFI fuel candidates between 2014 and 2022. They also publish the test plans and materials compatibility tests that are being performed. I would highly recommend taking the time to read them.

Materials Test Plan
Materials Test Matrix

Lessons Learned
Best Practices
Considerations