No Lead Aviation Fuel

brien23

brien23

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It's been a few years, what is going on with no lead aviation gas, thought it was down to one or two. With the new administration on fossil fuel they will probably do more than a nudge from the EPA, to force a transition to an unleaded fuel.
 
It's not the politics that has held up this change, it's that pesky physics thing. It's got to support the high compression engines which burn most of the 100LL
 
Maybe they gotta reduce the compression in those engines. Not a big deal to change pistons. Otherwise unleaded MoGas can offer a real solution.
 
nrpetersen said:
Not a big deal to change pistons.
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Except it would require a major alteration approval for each separate engine TCDS. It's my understanding there are several additives being looked at to replace the lead.
 
It's been 25 years since EPA ban on lead in fuel, just how long do you think Kerry and the new administration are going to wait.

1970: Congress passes the Clean Air Act. The EPA is formed and given the authority to regulate compounds that endanger human health.

1973: EPA mandates a phased-in reduction of lead content in all grades of gasoline.

1974: EPA requires availability of at least one grade of unleaded gasoline, in order to be compatible with 1975 make and model year vehicles. Lead damages the catalytic converters used in these new vehicles to control tailpipe emissions. Catalytic converters are still used in vehicles today.

1996: EPA bans the use of leaded fuel for on-road vehicles (leaded gasoline was down to 0.6 percent of 1996 gasoline sales). Lead is still used in some aviation fuels.
 
The legit players have been Shell, Swift, and GAMI. One dropped out, one dissolves paint, and one has insisted for over 10 years that they have the problem licked.
 
Bell206 said:
It's my understanding there are several additives being looked at to replace the lead.
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I wonder if that will lower the price from the $5.40 being charged by the only fuel provider at my home field... HAHAHAHAH yeah right.
 
brien23 said:
1996: EPA bans the use of leaded fuel for on-road vehicles (leaded gasoline was down to 0.6 percent of 1996 gasoline sales). Lead is still used in some aviation fuels.
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I guess we should be grateful airplanes do not run on roads nor use gasoline.

Why it hasn't been done before now is an engineering issue, just like why we don't have electric airplanes to fly across the country. You cannot repeal the laws of physics.
 
Mogas isn't really a replacement. The vapor pressure is too high. A good chunk of the fleet would have to be retrofitted with in tank boost pumps to keep airframe fuel lines from forming vapors.
 
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will44s said:
Mogas isn't really a replacement. The vapor pressure is too high. A good chunk of the fleet would have to be retrofitted with in tank boost pumps to keep airframe fuel lines from forming vapors.
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Not to mention there would have to be a separate supply chain for "Aviation grade" mogas. The mogas you buy at the gas station doesn't have the QC/QA that aviation fuels do. Especially with the influx and contamination of ethanol blends.
 
nrpetersen said:
Maybe they gotta reduce the compression in those engines. Not a big deal to change pistons. Otherwise unleaded MoGas can offer a real solution.
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Reducing compression would adversely affect power output and fuel consumption. This is not a practical solution for operators flying aircraft with high compression engines.
 
nrpetersen said:
Maybe they gotta reduce the compression in those engines. Not a big deal to change pistons. Otherwise unleaded MoGas can offer a real solution.
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Effectively that’s at least a top overhaul...$10,000-$15000 is a pretty big deal to ask of all piston owners.
Probably would also need to go to electronic ignition with knock sensors and variable timing...more money.
I predict the growth in GA aviation would come to an abrupt end.
 
A nearby airport has UL94, but is unable to sell it to the general public due to a noncompete agreement with their 100LL supplier.
 
I don't like Mogas in my car so I sure would not put it in an airplane.

The EPA governs how bad mogas can be made, not how good it can be made.

I used to sell race gas and back in the late 80s early 90s we had a true 93 octane unleaded. My 1988 Pontiac would get 38 mpg on that good stuff, and about 25 mpg on Exxon unleaded. But my gas sold for the ridiculous price of 2 bucks a gallon, back when Circle K sold regular unleaded for 0.899 cents per gallon. So not many folks bought it for the daily driver. It was made mainly for the SCCA guys that needed to use an unleaded gas.

Unleaded avgas can be made to equal the current 100LL. I have been out of the fuel business for many years so I do not know what the holdup is.
 
Lead is a cheap way to boost octane. You have to have 100 octane for the legacy engines that have high compression engines. Boosting fuel octane without lead would cost more. Pilots don't want to pay more, fuel suppliers don't want to increase their costs and eat into profits.

Environmental benefit? The amount of aviation fuel used is microscopic compared to what is burned in vehicles. While I too would like to see aviation go unleaded, it's kind of like the plastic straw craze last year. Might make you feel good, but in reality is will have an effect that would be so small I don't think you could even measure it.

Side note- Rotax engines HATE leaded gas. Creates a leaded mush in the oil. Prefers non leaded. But the legacy engines will be here for a long time - so we need 100 octane. I know leaded gas supposedly helps lubricates the valves, but I think that can be addressed in other ways.
 
[/QUOTE] Not to mention there would have to be a separate supply chain for "Aviation grade" mogas. The mogas you buy at the gas station doesn't have the QC/QA that aviation fuels do. Especially with the influx and contamination of ethanol blends.[/QUOTE]Ethanol contamination is a ridiculously easy check. Just add 10% water, shake, & see if the apparent water volume increases.

The only water I've encountered was 40 years ago in avgas, It was dissolved in solution and ice crystals plugged the gascolator.
 
wsuffa said:
Once the EPA and the "greens" set their sights on 100LL economics won't matter in respect to the regulations they impose.
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On the other hand, the FAA won't be working either.
 
nrpetersen said:
Why? high temperatures and high humidities reduce horsepower now yet we accept it. Maybe just reduce the max gross weight?
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Uh, no. Pay for expensive engine modifications so you can burn lower octane fuel to get less horsepower and thus less gross weight, less climb performance, less speed?

We "accept" high temperatures and humidity? ? That statement doesn't make sense. No one is Accepting / choosing what the weather is. I deal with warm weather and humidity by choosing to do other things, such as high compression engines making high horsepower.
 
UngaWunga said:
What engines require 100LL? My engine requires 80/87 aviation grade fuel, and I have the mogas STC. High compression engines require 91 octane with no lead. https://www.autofuelstc.com/stc_specs.phtml
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The engines in the planes I fly require 100LL. There are high compression engines in cars, and higher compression engines in planes.

And, per the website you posted, I guess you still need lead for valve lubrication unless it was overahauled using newer spec valves.

Burning an occasional tank of 100LL should not be necessary if the valve's guides and seats were constructed in accordance with the latest specifications. In view of the fact that 100LL is eventually slated to be replaced with an unleaded fuel, anyone facing an engine overhaul would be well advised to seek out hardened, newer spec parts.
 
MooneyDriver78 said:
Effectively that’s at least a top overhaul...$10,000-$15000 is a pretty big deal to ask of all piston owners.
Probably would also need to go to electronic ignition with knock sensors and variable timing...more money.
I predict the growth in GA aviation would come to an abrupt end.
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Well, it wouldn't be asked of ALL piston owners. Mainly just the turbo guys and a few of the high compression NA engines. Still isn't an easy sell, and obviously has performance ramifications for those affected.
 
WDD said:
And, per the website you posted, I guess you still need lead for valve lubrication unless it was overahauled using newer spec valves.
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This is not entirely true. lead is not needed for your valves.
 
nrpetersen said:
Why? high temperatures and high humidities reduce horsepower now yet we accept it. Maybe just reduce the max gross weight?
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So at low density altitudes, we'll have the equivalent of high-density-altitude performance. And what will we have then at high density altitudes?
 
Lindberg said:
So at low density altitudes, we'll have the equivalent of high-density-altitude performance. And what will we have then at high density altitudes?
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While not insignificant, I think you're overestimating the impact of a reduction in compression ratio. It would likely result in less than 5% decrease in peak HP. So a 300HP engine at 10:1 compression now makes 285HP at 8.5:1. It's not exactly world-ending. The impact on turbo charged/turbo-normalized engines may be different, but again shouldn't be like dropping major amounts of power. It's still losing power nonetheless.
 
Tom-D said:
This is not entirely true. lead is not needed for your valves.
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Well. The website posted states that leaded fuel is needed unless new spec valves are put in. Which I posted.
 
The purpose of the turbo is to pack more air and fuel into the cylinder. When they run it requires high octane as the pressures are quite high. You can’t run a turbo engine with low octane fuel.
 
WDD said:
Well. The website posted states that leaded fuel is needed unless new spec valves are put in. Which I posted.
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Then why could millions of hours run with lead with no modification.
 
WDD said:
The purpose of the turbo is to pack more air and fuel into the cylinder. When they run it requires high octane as the pressures are quite high. You can’t run a turbo engine with low octane fuel.
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Right, but the question becomes, what is the maximum boost/HP that can be run on 94UL without detonation? It's not about not being able to run turbo-charged engines, it's about how much power you can safely run. There are more turbo-charged engines in autos today than ever before, and most are running 87 to 91 octane (yes, not under constant high loads). I would guess that the overall power loss from a reduction in max boost while running 94UL could be doable for many applications, but no one is going to want to give that up without a fight.
 
Fixing this problem requires investment, which GA doesn't get anymore. The other way is government regulation, and that will further increase the price.
 
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