I will not be so silly as to take a firm position on anything that a large consortium of interests is uncertain of, a smorgasbord of interests ranging from regulators to manufacturers to universities to refiners to pumpers to users. Yet you seem certain the solution is to just drop the lead and keep on going as though nothing happened because it works in some airplanes and one supplier in particular is pushing it? Care to enlighten us?

The hardest part to reproduce is the block. And unlike auto clones, each aftermarket manufacturer would need FAA PMA approval. If you are planning on buying clone parts from two dozen different detroit aftermarket outfits they would ALL need to obtain FAA authorization. Not likely, only a few detroit autoparts suppliers have had any success breaking into aviation for that reason. If you ask them about AS9100, and they go "Huh?"...it's not going to happen.

The future AvGas debate fascinates me.

It's a declining market for several reasons.

The first concern is the fuel producers. Last I recall, there was only one AvGas refinery (is this still true?) which constrains supply and vastly increases the price of an already expensive fuel.

A second concern is the technical viability of the 94 octane for EVERY engine. Cirrus is mentioned repeatedly, but what about the owners of C414 C421 and similar turbocharged pistons what would become worthless without massive modification? Many of these are still work horses for local economies.

Is their only remaining option to invest in a PT6 or hope for an inexpensive Jet A piston (yeah right) to enter the market?

Not sure how you get that result. But, first, let me admit to one mistake in a previous post. The GAMI folks are promoting G100UL, not 94UL.

Their particular product, according to them, gets the job done technically. They have a full test cell for aircraft engines, and can run the tests as they did for AOPA recently at will. FAA asked them to have a full ATSM test done over about two years, as they asked of all their competitors.

At what cost per gallon for G100UL, I don't know. The rest is the same certification and economic debate, not technical.

As to 94UL, certainly that fuel, like mogas that is already approved in numerous airplanes, will work. Not technical. Not even legal if they just call it mogas with an STC that many planes already have.

Any of the above fuels, 94UL / G100UL / etc, would be better than 100LL for MOST airplanes. No more (or reduced) fouled plugs, less filth in the oil, etc.

As to the worst of the worst engines that need all the detonation help they can get... I don't know which might be worst, maybe a Lycoming in a Duke? A Rolls Royce in a P-51 Mustang? No, those airplanes will not be happy with something less than 100LL for the worst case scenarios (hot, high manifold pressure, carbon deposits that are heated in the combustion chamber, etc). Detonation will likely prevail. Heck, they probably would like 115 / 130 / 145 fuel !!!

What part of the fleet make up these turbocharged beasts? Each of them CAN be modified to operate without 100LL. Some of the fixes are quite simple. Lower manifold pressure. Some type of detonation monitoring. Lowered compression ratios. Not technical... economic and legal.

So, no, not saying every single plane can run UNMODIFIED on any fuel. I'm saying we should go to UL fuel as soon as possible, and that the limitations are not technical.

I believe Superior makes (made?) their own Lycoming "block" (split cases). The other examples I used, Volkwagen and Chevrolet engines, are also COMPLETE engines, including an aftermarket block.

The Volkswagen clone is in a certified German sailplane, I think.

They are out there. It can, and has been done.

Edit: almost forgot the Porsche powered, and FAA certified, Mooneys

As I already stated, the defunk Thielert Mercedes Benz diesels, and the current Mercedes Benz diesels, all FAA certified.

Well ok, for all we know GAMI G100UL may be the winner in the future fuel sweepstakes. It does sound like a good candidate. I'll try an scare up some news on it and post it here.

I don't know how many refineries there are, or even how important that number is. It's small, we can all agree, I hope.

Once lead is removed, I suspect you will have MORE refineries wanting to sell a relatively high profit margin, boutique fuel that doesn't cause EPA concerns / shipping / storage problems.



Well, I think that you're adding drama to a straight forward process.

First, the 94UL doesn't obsolete anything. In a mostly unmodified engine, there would likely be a decrease in engine horsepower, through a VERY simple process of reducing manifold pressure. Maybe ignition gets retarded a degree or three. Don't know. But the sky won't fall, sorry. They already have low compression pistons because of turbocharging. Obviously, the more difficult issue would be compensating for the "higher" compression ratio engines, which are not pressurized cabin twin Cessnas.

Second, there are alternatives to Tetra Ethyl Lead (TEL). I think the GAMI folks are using a base stock petroleum fuel that is probably (if I were betting man) 94UL. Why reinvent the wheel? Then, maybe throw in a few non-TEL like one of the following????

Alternative antiknock agents

Antiknock agents are grouped into "high-percentage" additives, such as alcohol, and "low-percentage" additives based on heavy elements. Since the main problem with TEL is its lead content, many alternative additives that contain less poisonous metals have been examined. A manganese-carrying additive, methylcyclopentadienyl manganese tricarbonyl (MMT or methylcymantrene), is used as an antiknock agent in Canada[citation needed], but its use as a fuel additive had been banned in the U.S. until 1995. Ferrocene, an organometallic compound of iron, has also been reported as an effective antiknock agent.
Lead replacement additives were scientifically tested, and some were approved by the Federation of British Historic Vehicle Clubs, at the UK's Motor Industry Research Association (MIRA) in 1999.[14]
High-percentage additives are organic compounds that do not contain metals, but they require much higher blending ratios, such as 20–30% for benzene and ethanol. It had also been established by 1921 that ethanol was an effective antiknock agent, but TEL was introduced for mainly commercial reasons to replace it.[7] Oxygenates, mainly methanol-derived MTBE and ethanol-derived ETBE, have largely substituted the need for TEL. MTBE has environmental risks of its own and there are also bans on its use. ETBE, on the other hand, requires more expensive ethanol as a starting material.
Improvements of the gasoline itself decrease the need for separate antiknock agents. Synthetic iso-octane and alkylate are examples of such blending stocks. Benzene and other high-octane aromatics can be also blended to raise the octane number, but they are disfavored today because of toxicity and carcinogenity.

A couple of other thoughts:

My old Cessna 172 with the trusty O-320-E2D Lycoming was FAA certified to run on 80/87 fuel, and STC'd to run on car gas. It needs neither 100LL, or 94UL, or G100UL, or Space Shuttle gas.

My next plane, the Cessna 177, was certified for mid 90's octane gas. I'm confident that 94UL would work with no modifications.

I believe my O-470 Baron would also be ok completely unmodified (sorry, don't remember the actual certified octane number) The OI-520 Baron, maybe not, but then, I don't remember the actual number, because I always used the green 100/130, or blue 100LL.

Fuel-------Color-----Amount of lead per gallon

80/87-----Red--- ---0.5 mL
100LL-----Blue------1.2 - 2.0 mL
100/130--Green----3.0 - 4.0 mL
115/145--Purple----4.6 mL

Oh, it can be done...the problem is that the aviation demand is not going to support the market

Aviation use of a converted auto engine is a risky endeavor, since any suitable engine is going to be modern and high-tech in order to meet the performance, weight, and reliability requirements of a broad-spectrum GA engine.

This means odds are very high that not every part part will be available aftermarket if the OEM shuts it down...and the odds of every part being PMA'ed? Astronomical, unless an aviation manufacturer adopted the engine and did all the leg work to ensure certification and sustained production/parts availability. This actually might be the best route, adoption vice clean-slate development.

The porsche thing was a lark, a marketing stunt.

VW engines don't count...that's the one engine that's been available since the 1930's in one form or another. It's suitable for a small homebuilt, but not for anything bigger. I can tear one down and rebuild it by the side of the road with a flashlight in my teeth, but I wouldn't trust most of them in an airplane. Msot of the current parts production is in latin america...

Exactly.

Here's a clean slate, Jet A burning, general aviation piston engine casting their own blocks!

DeltaHawk Diesel Engines